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Cold adaptation drives variability in needle structure and anatomy in Pinus sylvestris L. along a 1900 km temperate‐boreal transect
Functional Ecology
Abstract
Occupancy of cold habitats by evergreen species requires structural modification of photosynthetic organs for stress resistance and longevity. Such modifications have been described at interspecific level, while intraspecific variation has been underexplored.
To identify structural and anatomical traits that may be adaptive in cold environments, we studied intraspecific variability of needles of Scots pine ( P inus sylvestris L.), a wide‐ranging tree, along a 1,900 km temperate–boreal transect in Europe.
Needles from 20 sites representing mean minimum winter temperatures between −4.0 and −19.9°C and mean annual temperatures between 8.3 and −1.7°C were sampled for measurements of leaf mass per area ( LMA , g/m ² ), leaf density ( LD , g/cm ³ ) and 30 other morpho‐anatomical traits.
Needles from cold sites lived longer, were shorter, showed higher LMA and LD , had narrower and more collapse‐resistant tracheids, thicker epidermal cells with thicker cell walls and wider resin ducts occupying larger fraction of needle volume in comparison to needles from warmer sites.
Along the steep climatic gradient, needles presented a coordinated phenotypic spectrum of external and internal traits that are largely interpretable in functional, adaptive terms. This intraspecific pattern of covarying traits provides insight into the adaptive syndrome associated with stress tolerance and extended needle longevity under cold conditions of high latitudes.
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... The diversity of plant traits reflects the variety of solutions to the issues of resource utilization, conservation, and resistance to biotic and abiotic stresses (Jankowski et al., 2017;Wright et al., 2004;Wright et al., 2007;Díaz et al., 2016). These traits act as the response and adaptation to environmental changes and play important roles in the prediction of the influences of environmental conditions on plants and plant-mediated processes (Cornelissen et al., 2003;Cornelissen et al., 2007). ...
... Studies on the distribution of plant traits along the environmental gradient at the local or broad scale have yielded considerable data. The acquired information is beneficial to distinguish the drivers of intraspecies variation in the traits for the adaptation strategies of certain species (Moran et al., 2016;Jankowski et al., 2017;Wright et al., 2017) and the choices among various plants for the diverse adaptation strategies (Wright et al., 2004;Wright et al., 2007;Díaz et al., 2016). ...
... This phenomenon indicated that the thickened surface cell wall could help plants resist low temperature, drought, and other environmental factors that change with elevation, such as strong winds and high SR. Thickened cell walls reduce severe dehydration as a result of extracellular freezing caused by low temperatures, and this process allows the leaves to remain hydrated at low temperature (Jankowski et al., 2017) and prolongs the duration of cell activity. The surface cell wall is located between the active part of the cell and the boundary layers of the leaf. ...
Plant traits reflect the response and adaptation of plants to environmental changes and play important roles in the prediction of the effects of different environmental conditions on plants and plant-mediated processes. However, few studies have focused on the traits of nonvascular plants, such as bryophytes, although such plants are important participants in the primary productivity and biogeochemistry in harsh environments. In this study, the adaptive morphological traits and their interactions in the moss species that adapt to harsh and acute changeable environment were determined. Environmental factors that drive the changes in these traits were also evaluated. A total of 43 specimens of Didymodon rigidulus were collected from 38 sampling sites in arid and semi-arid regions in Tibet. Twelve morphological traits were investigated by microscope measurement, and then their interrelations and relations to environmental variables were quantified by employing Spearman’s correlation analysis, hierarchical partitioning analysis, and partial least squares path modeling. Results showed that along with the environmental gradient, the plant height, leaves, and cells of D. rigidulus had changed significantly, and these parameters were largely interpretable in functional and adaptive terms. The lower the mean annual temperature (MAT) was, the thicker was the surface cell wall and the wider was the cell cavity of D. rigidulus. The higher potential evapotranspiration (PET) was, the thicker was the surface cell wall but the smaller were the leaves. MAT and PET were the main driving forces for the development of such traits of D. rigidulus. These results provide important insight into the adaptive syndrome of nonvascular plants associated with stress tolerance in the varied and harsh environment in Tibet. This study indicated the importance of considering the effects of climate change, especially the warming temperature on species adaption and community assemblage.
... Location of the provenance trial is marked. Site coordinates are provided in a supporting data file (Marek et al., 2021) this species, often revealing the influence of latitude and associated temperature gradients on various traits (Jankowski et al., 2017;Mamayev, 1972). The responses of SD in Scots pine trees have been also studied experimentally, with decreases in SD caused by elevated CO 2 (in juvenile trees; Lin et al., 2001) and by elevated temperature (in 20-year old trees; Luomala et al., 2005). ...
... Overall, 122 sites were sampled spanning 32.25°of latitude and 50.77°of longitude. Stands of Scots pine were of natural origin, or, in the case of Poland, planted with local seeds as confirmed by local foresters (Jankowski et al., 2017;Jasińska et al., 2014;Oleksyn et al., 2020). A total of 10-30 dominant trees (25 at the majority of sites) of reproductive age (over 80 years old) were selected at each site, and a fully sunlit branch was cut from each Scots pine tree at a height of 2-10 m using a pole pruner. ...
... This phenomenon occurs because the cells in larger leaves are not only more numerous but also larger in size, relative to smaller leaves, including pavement cells that separate stomata (Delgado et al., 2011). In our study, however, a latitudinal decrease in needle length, observed especially between Central Europe and Northern Scandinavia (Jankowski et al., 2017), was accompanied by a reduction rather than an increase in SD proj . This result does not support the direct effect of temperature on SD. ...
The commonly observed negative relationship between stomatal density (SD) and atmospheric CO2 has led to SD being proposed as an indicator of atmospheric CO2 concentration. The use of SD as a proxy for CO2, however, has been hampered by an insufficient understanding of intraspecific variation of this trait. We hypothesized that SD in Pinus sylvestris, a widely-distributed conifer, varies geographically and that this variation is determined by major climatic variables. By sampling needles from naturally-growing trees along a latitudinal range of 32.25 degrees, equivalent to 13.7°C gradient of mean annual temperature (MAT) across Europe, we found that SD decreased from the warmest southern sites to the coldest sites in the north at a rate of 4 stomata per mm² for each 1°C, with MAT explaining 44% of the variation. Additionally, samples from a provenance trial exhibited a positive relationship between SD and the MAT of the original localities, suggesting that high SD is an adaptation to warm temperature. Our study revealed one of the strongest intraspecific relationships between SD and climate in any woody species, supporting the utility of SD as a temperature, rather than direct CO2, proxy. In addition, our results predict the response of SD to climate warming.
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... URL: www.rjbn.uh.cu ISSN 2410-5546 RNPS 2372 (DIGITAL) -ISSN 0253-5696 RNPS 0060 (IMPRESA) largo plazo afectará la supervivencia y el crecimiento de la planta (Grill & al. 2004, Huang & al. 2016). Variaciones en la morfología y la estructura anatómica de la acícula entre individuos y poblaciones obedece a diferencias en las condiciones de edátopo y los regímenes de humedad del hábitat donde crecen , Tiwari & al. 2013, Ghimire & al. 2014, Meng & al. 2018) y pueden ser usados como un método rápido para explorar la variación genética entre poblaciones (Boratyńska & al. 2015a, 2015b, Zhang & al. 2017. ...
... Variaciones en la morfología y la estructura anatómica de la acícula entre individuos y poblaciones obedece a diferencias en las condiciones de edátopo y los regímenes de humedad del hábitat donde crecen , Tiwari & al. 2013, Ghimire & al. 2014, Meng & al. 2018) y pueden ser usados como un método rápido para explorar la variación genética entre poblaciones (Boratyńska & al. 2015a, 2015b, Zhang & al. 2017. Las dimensiones y distribución de los tejidos en la anatomía de la acícula han sido estudiadas fundamentalmente para especies con amplios rangos de distribución (Boratyńska & al. 2015a, Jankowski & al. 2017, Köbölkuti & al. 2017) y ambientes contrastantes (Boratyńska & al. 2015a, 2015b, Hodžić & al. 2020. Sin embargo, tales estudios son escasos en especies insulares donde las condiciones ambientales son más homogéneas, a pesar de su gran importancia económica y ecológica, y de ser usadas en plantaciones de distintos lugares del mundo, como es el caso de Pinus caribaea Morelet. ...
... (Ghimire & al. 2014), P. yunnanensis Franch. (Huang & al. 2016) y Cedrus atlantica (Endl.) G. Manetti ex Carrière (Bakkali & Amraoui 2018). ...
Variation of anatomical characters is crucial in the recognition of ecological adaptability, especially in Pinus. Pinus caribaea var. caribaea is an endemic taxon of Western Cuba that grows in pure populations or sympatry with Pinus tropicalis and occupies a great variety of ecotopes that are also distinguished by the characteristics of the edatope. The objective of this research is to determine the anatomical variation of the needles as an adaptive differential response to the environmental conditions determined by lithology, altitude and slope. From 20 to 30 individuals from all the ecotopes where the taxon grows naturally were sampled. Cross sections were made of 10 needles from each tree and 12 anatomical variables, related to water regulation, transport and storage of metabolites, were assessed. The results of the statistical analysis revealed significant differences between ecotopes. The principal component analysis showed a relationship between anatomical variables that follow a functional pattern of water regulation and assimilation. The cluster and discriminant analysis made possible to distinguish the formation of groups by the relationship of the anatomical variables, mainly due to the effect of lithology, and those that contributed the most to differentiate them were those of water regulation, primary metabolism together with cuticle thickness. The results are a contribution to the local conservation of the taxon since the structure of the anatomical variation is a consequence of the genetic evolution of the populations and are very important in ecological and for silvicultural management.
Citation: Geada-López, G., Sotolongo-Sospedra, R., Pérez-del Valle, L. & Ramírez-Hernández, R. 2021. Diferenciación anatómica foliar en poblaciones naturales de Pinus caribaea var. caribaea (Pinaceae) en Pinar del Río y Artemisa, Cuba. Revista Jard. Bot. Nac. Univ. Habana 42: 175-188.
Received: 23 March 2021. Accepted: 13 May 2020. Online: 21 July 2021. Editor: José Angel García-Beltrán.
... Регуляторні механізми, які визначають розмір і форму хвої, є життєво важливими, оскільки дають можливість рослинам адаптуватися до умов довкілля (Gebauer et al. 2018). Анатомічні перетворення рослин одночасно регулюють ендогенні та екологічні фактори (Bongard-Pierce et al. 1996, Reich et al. 1996, Gebauer et al. 2017, Jankowski et al. 2017. Також не можна виключати спадкову складову особливостей морфології та анатомії хвої (Keng & Litl 1961, Mamaev 1973, Prokazin & Bonn 1976, Kuzmin et al. 2004, Jankowski et al. 2017, Galdina & Khazova 2019. ...
... Анатомічні перетворення рослин одночасно регулюють ендогенні та екологічні фактори (Bongard-Pierce et al. 1996, Reich et al. 1996, Gebauer et al. 2017, Jankowski et al. 2017. Також не можна виключати спадкову складову особливостей морфології та анатомії хвої (Keng & Litl 1961, Mamaev 1973, Prokazin & Bonn 1976, Kuzmin et al. 2004, Jankowski et al. 2017, Galdina & Khazova 2019. ...
... Анатомічні перетворення рослин одночасно регулюють ендогенні та екологічні фактори (Bongard-Pierce et al. 1996, Reich et al. 1996, Gebauer et al. 2017, Jankowski et al. 2017. Також не можна виключати спадкову складову особливостей морфології та анатомії хвої (Keng & Litl 1961, Mamaev 1973, Prokazin & Bonn 1976, Kuzmin et al. 2004, Jankowski et al. 2017, Galdina & Khazova 2019. ...
Метою дослідження був пошук маркерних ознак, які ідентифікують дерева, та взаємозв’язків морфолого-анатомічних показників хвої дерев сосни звичайної (Pinus sylvestris L.) на основі вивчення мінливості ознак у насадженні ДП «Тростянецьке лісове господарство» Сумської області. Гілки з хвоєю заготовлено із середньої частини крони 31 дерева в умовах свіжого субору. Визначення зв’язків між показниками здійснено кореляційним, графічним і регресійним методами аналізу. Виявлено, що амплітуда варіювання довжини дворічної хвої була на 18 % більшою, ніж однорічної. Коефіцієнти варіації більшості морфолого-анатомічних показників дерев відповідають низькому та середньому рівням ендогенної мінливості, підвищеним рівень мінливості є лише для показника відстані між провідними пучками в центральному циліндрі. До морфолого-анатомічних ознак хвої, які диференціюють дерева, належать: довжина хвої, площу її поперечного перерізу, ширина хвої, ширина центрального циліндра та кількість смоляних каналів. Зроблено припущення про можливість використання маркером мікропопуляційного рівня співвідношення індексу форми центрального циліндра та індексу форми поперечного перерізу хвої. Ключові слова: Pinus sylvestris L., параметри хвої, пагони, центральний циліндр, маркерні ознаки, смоляні канали.
... A close association of leaf properties with habitat temperature is expected especially in winter-green species, the foliage of which must survive one or more seasons with subfreezing temperatures (Wisniewski et al. 2014, Zanne et al. 2014, Jankowski et al. 2017. Intraspecific trait patterns in relation to altitudinal or latitudinal temperature gradients revealed by field sampling indeed indicate that adaptation to cold might have influenced the evolution of leaf structure. ...
... Intraspecific trait patterns in relation to altitudinal or latitudinal temperature gradients revealed by field sampling indeed indicate that adaptation to cold might have influenced the evolution of leaf structure. Low winter temperature favors small leaves, as indicated by a reduction in needle length with decreasing habitat temperature in conifers (Pravdin 1969, Nobis et al. 2012, Jankowski et al. 2017) and leaf lamina surface area in angiosperms (Ogaya and Peñuelas 2007). Similarly, low temperature at least partly explains geographic and altitudinal patterns of occurrence of leaves with high LMA in gymnosperm (Hultine andMarshall 2000, Jankowski et al. 2017) and angiosperm (Ogaya and Peñuelas 2007, Pensa et al. 2010, Niinemets 2015 species. ...
... Scots pine (Pinus sylvestris L.), a temperate-boreal evergreen conifer with one of the broadest distribution ranges of all trees, is a favorite species for the study of intraspecific variability (Pravdin 1969, Mamayev 1972, Ruby and Wright 1976, Reich et al. 1996, Novikova and Milyutin 2006, Androsiuk et al. 2011, Pakharkova et al. 2014. Interestingly, in this, and several other temperate/boreal conifer species, longevity of needles increases toward the northern ends of their distribution ranges, setting requirements for adaptative traits that will ensure extended survival under severe temperature conditions , Jankowski et al. 2017. Recently, we have reported covariation of needle anatomical traits with habitat temperature and needle longevity for Scots pines sampled between temperate Central Europe and boreal northern Scandinavia. ...
The correlations of phenotypic traits with environmental drivers suggest that variability of these traits is a result of natural selection, especially if such trait correlations are based on genetic variability. We hypothesized that in situ correlations of structural needle traits of Scots pine (Pinus sylvestris L) with minimal winter temperature (Tmin) reported previously from a temperate/boreal transect would be conserved when plants are cultivated under common conditions. We tested this hypothesis by analyzing needles from two common gardens located in the temperate zone, one including adult trees and the other juvenile seedlings. The majority of adult needle traits for which correlations with Tmin were found in the field turned out to be under environmental influence. In contrast, the majority of traits studied in juvenile needles were correlated with the original Tmin suggesting the role of past natural selection in shaping their variability. Juvenile needles thus appeared to be inherently less plastic than adult needles, perhaps reflecting the stronger selective pressure acting during juvenile, as compared with adult, ontogenetic stage. Genetically based cold-climate adaptation in either juvenile or adult needles, or both, involved an increase in leaf mass per area and leaf density, decrease in needle length, reduction in the amount of xylem and phloem, increase in thickness of epidermis, decrease in tracheid diameter and increase in tracheid density, and increase in diameter and volume fraction of resin ducts. We also show that at least some traits, such as transverse xylem and phloem areas and number of fibers, scale with needle length, suggesting that climate-related trait variation may also be mediated by changes in needle length. Moreover, slopes of these allometric relationships may themselves be plastically modified. The phenotypic syndrome typical of needles from cold environments may thus be under environmental, genetic and allometric control.
... (6,(12)(13)(14) La variación en la anatomía acicular ha sido estudiada fundamentalmente para especies con amplios rangos de distribución y ambientes contrastados. (10,11,(15)(16)(17) Sin embargo, son escasos en especies insulares donde aparentemente las condiciones ambientales son más homogéneas y son usadas en plantaciones de distintos lugares del mundo, como es el caso de Pinus caribaea. Gran parte de estos análisis se centran en pinos continentales y de amplia distribución. ...
... Se ha detectado que la mayor densidad de canales se asocia con áreas de menor disponibilidad de humedad y su incremento en número y tamaño está correlacionado en Pinus yunnanensis con disminuciones de la precipitación y aumento de la temperatura que contribuye a reducir la influencia de la extrema sequía y el calor similar a lo encontrado en esta especie. (7,15,16) Los resultados en este estudio apuntan a que en Los contornos corresponden a elipses de predicción al 95 % de probabilidad. GC, grosor de la cutícula; GEp, grosor de la epidermis; GH, grosor de la hipodermis; CH, número de capas de células de la hipodermis; NoE, número de estomas; PT, grosor del tejido de transfusión; NC, número de canales; PC, grosor del parénquima clorofílico; DCi, diámetro del canal izquierdo; DCd, diámetro del canal derecho; ...
Introduction: Variations in needle anatomy can be adaptive responses or interpopulation acclimatization to edaphoclimatic stress, especially of species that develop in extreme environments. Pinus caribaea var. caribaea and Pinus tropicalis are distributed in western Cuba, mainly in the province of Pinar del Río, where they form pure populations or in sympatry.
The objective of this study was to determine the anatomical variation of the needles of both species as a differential adaptive response to environmental conditions determined by lithology, altitude and slope.
Methods: Between 20 and 30 individuals were sampled from all the ecotopes where both taxa grow naturally. The studies are fundamentally based on multivariate statistical analyses.
Results: The analyzes used allowed to differentiate the two taxa from the point of view of their foliar anatomy, both present their own variations to adapt to the same environment. For P. caribaea, the formation of groups is distinguished by the relationship of the anatomical variables, mainly due to the effect of the lithology and those that most contributed to differentiate them were those of water regulation, primary metabolism together with the thickness of the cuticle. In P. tropicalis, the results revealed significant differences between ecotopes, fundamentally with respect to the one located in the quartzite sands with high silica content, the formation of groups is given fundamentally by the effect of the lithology. The variables that most contributed to discriminate between ecotopes were those related to water regulation, number and diameter of resin channels and cuticle thickness.
Conclusions: The availability of water and nutrients in the substrate are the factors that most influence anatomical variation. The results contribute to the local conservation of the taxon since the structure of the anatomical variation is a consequence of the genetic evolution of the populations and they are very important in ecological studies and for silvicultural management
... These leaf traits, including Chlb, Gs, LDW, LFW, LL, LW, PL and SLW, are closely related to the growth and stress resistance of Chinese chestnut. Leaf length, width, thickness, area are affected by genotype and environment [39][40][41][42]. Leaf shape and number also important traits that determine a plant's appearance, photosynthesis capacity, light energy utilization, yield, water WUE, and even desirability to consumers [43][44][45]. ...
... These leaf traits, including Chlb, Gs, LDW, LFW, LL, LW, PL and SLW, are closely related to the growth and stress resistance of Chinese chestnut. Leaf length, width, thickness, area are affected by genotype and environment [39][40][41][42]. Leaf shape and number ...
Chinese chestnut is an economically and ecologically valuable tree species that is extensively cultivated in China. Leaf traits play a vital role in the photosynthetic capacity, chestnut yield, and quality, making them important breeding objectives. However, there has been limited research on constructing high-density linkage maps of Chinese chestnut and conducting quantitative trait loci (QTL) analyses for these leaf traits. This knowledge gap has hindered the progress of selection in Chinese chestnut breeding. In this study, we selected a well-established interspecific F1 population, consisting of Castanea mollissima ‘Kuili’ × C. henryi ‘YLZ1’, to construct comprehensive genetic maps for chestnut. Through the use of a genotyping-by-sequencing (GBS) technique, we successfully created a high-density linkage map based on single-nucleotide polymorphisms (SNPs) from the F1 cross. The results showed that 4578 SNP markers were identified in the genetic linkage map, and the total length was 1812.46 cM, which was distributed throughout 12 linkage groups (LGs) with an average marker distance of 0.4 cM. Furthermore, we identified a total of 71 QTLs associated with nine chestnut leaf traits: chlorophyll b content (chlb), stomatal conductance (Gs), leaf area (LA), leaf dry weight (LDW), leaf fresh weight (LFW), leaf length (LL), leaf width (LW), petiole length (PL), and specific leaf weight (SLW). These QTLs were identified based on phenotypic data collected from 2017 to 2018. Notably, among the 71 QTLs, 29 major QTLs were found to control leaf area (LA), leaf dry weight (LDW), and leaf width (LW). The high-density genetic mapping and QTL identification related to leaf traits in this study will greatly facilitate marker-assisted selection (MAS) in chestnut breeding programs.
... Once all the segments were dated, the length of each primary growth was measured, and the six innermost tree rings were marked. We selected six years because it is the maximum needle longevity that the Scots pine usually shows (see also Drenkhan et al. 2006;Poljanšek et al. 2015;Pouttu and Dobbertin 2000;Jankowski et al. 2017). In a third phase, each of the rings that harbor needle scars were delimited by marking the latewood with the help of a binocular magnifying glass (Fig. S3b). ...
... Wet and snowy winters may recharge soil water reserves and positively influence needle development and tree growth in spring (Camarero et al. 2015a). This finding differs from other results on cold-limited Scots pine forests in northern Europe where needle longevity, leaf density, and leaf mass per area decreased as winter minimum temperature increased, but needle length increased (Pensa et al. 2010;Jankowski et al. 2017). ...
Key message
Reconstruction of needle dynamics reveals prolonged drought legacy effects on crown condition that represent early warnings of drought-induced dieback in Scots pine.
Abstract
Understanding the mechanisms of drought-induced forest dieback and tree mortality is a priority for predicting forest responses to climate change. However, long-term information on drought impacts on crown dynamics and how it relates to tree water and carbon economy is still lacking. Comparing declining and non-declining Scots pines at the same site, we quantified primary and secondary growth and intrinsic water-use efficiency (WUEi). Further, we reconstructed the needle production and the annual total number of needles using the Needle Trace Method. Here, we reconstructed the apical needles through the assessment of 2460 longitudinal sections. We fitted partial least squares regression models to assess climate influence on primary and secondary growth and needle dynamics, and then linear mixed models using climate covariates and discerning between health status in the 1975–2016 period. Finally, we analyzed drought legacy effects applying a Bayesian hierarchical framework. We detected the highest differences between health tree classes in the annual total number of needles during the warm-dry 1980s. Declining trees responded more negatively to climate than non-declining conspecifics and showed a higher variability of drought legacy effects. We found significant drought legacy effects in the annual total number of needles up to 3 years after a drought. The warm, dry 1980s, that preceded the dieback, showed the highest δ¹³C values since the 1970s. Declining trees showed higher WUEi than non-declining trees from the 2000s onwards. Our study sheds light on the major role of needle dynamics in dieback episodes and illustrates how past drops in needle production may be interpreted as early warnings of drought-induced dieback in Scots pine.
... Increased temperature, however, has a more variable effect, initiating earlier terminal budbreak at the beginning of the growing season-though not always (Adams et al., 2015)-and limiting growth later in the growing season (Olszyk et al., 1998). Conversely, in energy-limited systems, needle length is often positively correlated with temperature (Jankowski et al., 2017;Tyukavina et al., 2019;Zhai et al., 2012) while precipitation has a more variable and often decoupled effect (Jankowski et al., 2017;Ordoñez et al., 2009;Reich, Rich, et al., 2014;Tyukavina et al., 2019). These contrasting growth responses suggest that declines in precipitation will differentially impact leaf traits within energy-and water-limited systems, potentially leading to threshold effects during drought . ...
... Increased temperature, however, has a more variable effect, initiating earlier terminal budbreak at the beginning of the growing season-though not always (Adams et al., 2015)-and limiting growth later in the growing season (Olszyk et al., 1998). Conversely, in energy-limited systems, needle length is often positively correlated with temperature (Jankowski et al., 2017;Tyukavina et al., 2019;Zhai et al., 2012) while precipitation has a more variable and often decoupled effect (Jankowski et al., 2017;Ordoñez et al., 2009;Reich, Rich, et al., 2014;Tyukavina et al., 2019). These contrasting growth responses suggest that declines in precipitation will differentially impact leaf traits within energy-and water-limited systems, potentially leading to threshold effects during drought . ...
Predicted increases in extreme droughts will likely cause major shifts in carbon sequestration and forest composition. Though growth declines during drought are widely documented, an increasing number of studies have reported both positive and negative responses to the same drought. These divergent growth patterns may reflect thresholds (i.e., nonlinear responses) promoted by changes in the dominant climatic constraints on tree growth. Here we tested whether stemwood growth exhibited linear or nonlinear responses to temperature and precipitation and whether stemwood growth thresholds co-occurred with multiple thresholds in source and sink processes that limit tree growth. We extracted 772 tree cores, 1,398 needle length records, and 1,075 stable isotope samples from 27 sites across whitebark pine's (Pinus albicaulis Engelm.) climatic niche in the Sierra Nevada. Our results indicated that a temperature threshold in stemwood growth occurred at 8.4 °C (7.12 - 9.51°C; estimated using fall-spring maximum temperature). This threshold was significantly correlated with thresholds in foliar growth, as well as carbon (δ13 C) and nitrogen (δ15 N) stable isotope ratios, that emerged during drought. Multiple, co-occurring thresholds reflected the transition between energy and water limited tree growth (i.e., the E-W limitation threshold). This transition likely mediated carbon and nutrient cycling, as well as important differences in growth-defense tradeoffs and drought-adaptations. Further, whitebark pine growing in energy limited regions may continue to experience elevated growth in response to climate change. The positive effect of warming, however, may be offset by growth declines in water limited regions, threatening the long-term sustainability of the recently listed whitebark pine species in the Sierra Nevada.
... Past reports have mostly explored interspecific variability, with the associated wide trait divergence and often complex evolutionary histories of sampled taxa (Collins et al., 2016;Wang et al., 2017). Scots pine, with its remarkable intraspecific clines in key root and needle traits along an extended temperate-boreal gradient (Jankowski et al., 2017;Ostonen et al., 2017;Zadworny et al., 2017), offers a convenient system to explore root-leaf relations. ...
... Needles sampled along the same or similar South-to-North transects exhibit decreased specific leaf area (SLA; Jankowski et al., 2017), and decreased foliar N & P (phosphorus) concentration (Oleksyn et al., 2003;Ťupek et al., 2015), however, it is unclear whether these changes are due to genetic differences among populations or plastic responses to the local environment. Although high allocation to absorptive roots may be expected to enhance needle nutrient content, the net effect of possessing such roots will depend on local availability of resources. ...
Harsh environmental conditions affect both leaf structure and root traits. However, shoot growth in high‐latitude systems is predominately under photoperiod control while root growth may occur for as long as thermal conditions are favorable. The different sensitivities of these organs may alter functional relationships above‐ and belowground along environmental gradients. We examined the relationship between absorptive root and foliar traits of Scots pine trees growing in situ along a temperate‐boreal transect and in trees grown in a long‐term common garden at a temperate latitude. We related changes in foliar nitrogen, phosphorus, specific leaf area, needle mass and 13C signatures to geographic trends in absorptive root biomass to better understand patterns of altered tree nutrition and water balance. Increased allocation to absorptive fine roots was associated with greater uptake of soil nutrients and subsequently higher needle nutrient contents in the northern provenances compared with more southern provenances when grown together in a common garden setting. In contrast, the leaf δ13C in northern and southern provenances were similar within the common garden suggesting that higher absorptive root biomass fractions could not adequately increase water supply in warmer climates. These results highlight the importance of allocation within the fine‐root system and its impacts on needle nutrition while also suggesting increasing stomatal limitation of photosynthesis in the context of anticipated climatic changes.
... Esta respuesta se ha observado en algunas especies asociado a un gradiente de precipitación y humedad, tales como P. sylvestris (Donnelly & al. 2016, Köbölkuti & al. 2017, Galdina & Khazova 2019, P. thunbergii (Ghimire & al. 2014), P. tabuliformis (Zhang & al. 2017) y P. yunnanensis (Huang & al. 2016). Aunque no se comprende totalmente el rol de los canales de resina en la regulación del agua (Farrell & al. 1991, Krokene & Nagy 2012, se ha detectado que la mayor densidad de canales se asocia a áreas de menor disponibilidad de humedad (Donnelly & al. 2016, Jankowski & al. 2017 y su incremento en número y tamaño está correlacionado, en P. yunnanensis con disminuciones de precipitación y aumento de la temperatura que contribuye a reducir la influencia a la extrema sequía y calor (Huang & al. 2016). ...
... Bajo la tesis de que especies con amplios rangos de distribución tienen mayor potencial para exhibir una gran variación intraespecífica en morfología, fisiología, fenología y crecimiento (Zhang & al. 2017, Jankowski & al. 2017, Köbölkuti & al. 2017, Tyukavina & al. 2019, cabría esperar una pequeña variación anatómica en especies con una reducida área de distribución y sin grandes contrastes en clima y vegetación. Los resultados obtenidos reflejan que, en especies insulares, en especial las cubanas, las condiciones del sitio o su origen geológico hace que desplieguen una variación fenotípica, que determina su adaptación a edátopos diferentes. ...
Las variaciones en la anatomía foliar pueden ser respuestas adaptativas o de aclimatación interpoblacional al estrés edafoclimático, sobre todo de especies que se desarrollan en ambientes extremos. Pinus caribaea var. caribaea y P. tropicalis se distribuyen en el occidente de Cuba, principalmente en la provincia de Pinar del Río donde forman poblaciones puras o en simpatría. Es objetivo de este trabajo comparar las características anatómicas distintivas de las acículas de ambos taxones en diferentes localidades donde se asocian simpátricamente. Para ello se realizaron cortes transversales de las acículas y se evaluaron 14 variables anatómicas. Los análisis estadísticos empleados permitieron diferenciar claramente los dos taxones y ambos presentan variaciones propias para adaptarse a un mismo ambiente. El análisis de componentes principales mostró que dentro de cada taxón las poblaciones se segregan en relación al edátopo donde se desarrollan. Para P. caribaea var. caribaea las variables anatómicas que más contribuyeron a la variación y ordenación fueron el número de estomas, grosor y número de capas de células de la hipodermis; en P. tropicalis el grosor de la cutícula y el parénquima clorofílico, y para ambos taxones el tipo de canal fue inequívocamente endonales y marginal.
... Scots pine is one of the most widely distributed conifers in the Northern Hemisphere (San-Miguel-Ayanz et al., 2016). The widespread occurrence of the species demonstrates an ability to adapt over spatially heterogeneous environments, e.g., large temperature and photoperiod variations (Rehfeldt et al., 2002;Jankowski et al., 2017). A clear illustration of local adaptation is that northern populations set buds and develop autumn frost tolerance significantly earlier than southern populations (Hurme et al., 1997;Andersson and Fedorkov, 2004;Savolainen et al., 2004;Jankowski et al., 2017). ...
... The widespread occurrence of the species demonstrates an ability to adapt over spatially heterogeneous environments, e.g., large temperature and photoperiod variations (Rehfeldt et al., 2002;Jankowski et al., 2017). A clear illustration of local adaptation is that northern populations set buds and develop autumn frost tolerance significantly earlier than southern populations (Hurme et al., 1997;Andersson and Fedorkov, 2004;Savolainen et al., 2004;Jankowski et al., 2017). Autumn frost tolerance, ''cold hardiness'' hereafter, is a critical fitness component in the northern climate as it determines the mortality and survival of seedlings and thus the success rates of forest regeneration. ...
... There could be mechanical and chemical reasons for the preference of pine needles: Pine needles may have a mechanical advantage in size and structure over individual spruce needles, as pine needles are usually found as a bundle of 2-3 extremely narrow needles per sheath covering the base of the needle bundle. In addition, a greater thickness of outer epidermal walls of pine needles can support mechanical strength and protect the pine needles from desiccation, especially in winter (Jankowski et al. 2017). This can support the durability of the nest building material. ...
... This could additionally contribute to longevity of the nest cover. From a chemical point of view, the thick-walled epidermis contributes to the defense against herbivores by forming specialized resin channels (Jankowski et al. 2017). Resin is an important component of RWA nests because of its stabilizing and antibacterial effect (Christe et al. 2003). ...
0 Abstract We used presence/absence data of 5,160 red wood ant nests (RWA; Formica polyctena) acquired in a systematic large-scale area-wide survey in two study areas (≈350 ha) in the Oberpfalz, NE Bavaria, Germany to explore for the first time the influence of variable (e.g., forest type, tree age) and quasi-invariant factors (e.g., tectonics, geochemical composition of the bedrock) on nest size, spatial distribution and nest density for Variscan granites. A combination of the forest type (mature pine-dominated forests (80-140 years) as main variable factor and the geochemical property of the Variscan granites with their high natural Radon potential and moderate heat production as main quasi-invariant factor could explain the high nest numbers in both study areas. In addition, the spatially clustered distribution patterns of the observed nests suggest a strong interaction between nests and their quasi-invariant environment, especially the directionality of the present-day stress field and the direction of the tectonically formed "Erbendorfer Line". In general, such a combination of variable and quasi-invariant factors can be addressed as particularly favorable RWA habitats.
... LMA is an indicator of foliar anatomical traits and determines how much biomass can be made for a given investment in light-interception (leaf) area (Lambers and Poorter, 1992;Poorter et al., 2009;Poorter et al., 2010). It also reflects the mechanical toughness of leaves and tends to be positively correlated with leaf longevity (Reich et al., 2014;Jankowski et al., 2017). At moderately low light intensity, leaf area in the present study was significantly higher than in the control and at extremely low light intensity, but LMA was not significantly different from the control. ...
... 3.94 ± 0.11a 4.36 ± 0.02b 3.78 ± 0.12a Chl a/b 2.28 ± 0.04a 2.14 ± 0.03b 2.46 ± 0.02c Car/Chl a + b 0.08 ± 0.002a 0.08 ± 0.001b 0.09 ± 0.001c W. Zhang et al. Industrial Crops & Products 122 (2018) 392-401 LMA also means a higher fraction of air space and lower dry matter accumulation in the plant tissues and lower mesophyll conductance, which together lead to these plants having the highest intercellular CO 2 concentration at extremely low light intensity (Vile et al., 2005;Jankowski et al., 2017). Light is a vital resource for plants, and light deficiency can directly alter development of the photosynthetic apparatus and the plant's photosynthetic capacity (Wu et al., 2017). ...
Total saikosaponin yield in Bupleurum chinense DC. roots depends on the root biomass production and the saikosaponin content in roots, which are both affected by abiotic factors. Bupleurum chinense is relatively shade-tolerant. To test how total saikosaponin yield responds to light conditions, different light intensities (500, 200, and 50 μmol m⁻² s⁻¹) were established in artificial climate incubators. Responses of plant morphological and physiological characteristics and of saikosaponin synthesis to different light intensities were measured to find suitable light conditions for improving total saikosaponin yield. Among these light conditions, moderately low light intensity (MLI, 200 μmol m⁻² s⁻¹) produced plants with the highest leaf area, chlorophyll content, effective quantum yield of PSII (ΦPSII), photochemical quenching coefficient (qP), electron transport rate (ETR), maximum carboxylation efficiency (Vcmax), maximum electron transport rate (Jmax), and triose phosphate utilization rate (VTPU), which suggests a well-functioning photosynthetic apparatus capable of fully utilizing the limited light energy. Moreover, the plants had the highest root–shoot ratio, saikosaponin content, and total saikosaponin yield, which indicates that they allocated more resources to storage and defensive adaptations. Under extremely low light intensity (ELI, 50 μmol m⁻² s⁻¹), more energy was partitioned to photoprotection, and strong oxidation resistance developed, but saikosaponin accumulation and root biomass were lowest due to greatly reduced carbon assimilation. The MLI improved both the quantity and the quality of herbal extracts from B. chinense: the total saikosaponin yield was 1.3 times the corresponding value of the control (500 μmol m⁻² s⁻¹), and lower illumination levels were counterproductive. Our results suggest that B. chinense would be suitable for introducing to an agroforestry system.
... Plant functional traits (PFTs) are easily measured plant attributes including morphological, physiological, or phenological characteristics [1,2]. PFTs are closely related to plant ecological functions and reflect plant adaptability and performance in important ecological functions such as resource acquisition, allocation, conservation, and stress response [3,4]. Research on PFTs contributes to a better understanding of plant adaptations and survival strategies, as well as their interactions with the environment [5,6]. ...
Investigating intraspecific trait variability is crucial for understanding plant adaptation to various environments, yet research on lithophytic mosses in extreme environments remains scarce. This study focuses on Indusiella thianschanica Broth. Hal., a unique lithophytic moss species in the extreme environments of the Tibetan Plateau, aiming to uncover its adaptation and response mechanisms to environmental changes. Specimens were collected from 26 sites across elevations ranging from 3642 m to 5528 m, and the relationships between 23 morphological traits and 15 environmental factors were analyzed. Results indicated that coefficients of variation (CV) ranged from 5.91% to 36.11%, with gametophyte height (GH) and basal cell transverse wall thickness (STW) showing the highest and lowest variations, respectively. Temperature, elevation, and potential evapo-transpiration (PET) emerged as primary environmental drivers. Leaf traits, especially those of the leaf sheath, exhibited a more pronounced response to the environment. The traits exhibited apparent covariation in response to environmental challenges and indicated flexible adaptive strategies. This study revealed the adaptation and response patterns of different morphological traits of I. thianschanica to environmental changes on the Tibetan Plateau, emphasizing the significant effect of temperature on trait variation. Our findings deepen the understanding of the ecology and adaptive strategies of lithophytic mosses.
... It is well known that conifer species produce traumatic resin ducts in response to environmental stress stimuli, such as climatic factors, herbivore browsing, or when subjected to methyl jasmonate treatment (Krokene and Nagy, 2012;Lombardero et al., 2002;Martin et al., 2002;McKay et al., 2003;Jankowski et al., 2017;Vázquez-González et al., 2019). The higher number of resin ducts especially in the needles from the High radiation site (Fig. 4) where growth was impaired, may indicate that resins play a role in protection against stress due to ionising radiation and that this occurs at the expense of growth. ...
The Chernobyl Nuclear Power Plant (ChNPP) accident in 1986 resulted in extremely high levels of acute ionising radiation, that killed or damaged Scots pine (Pinus sylvestris) trees in the surrounding areas. Dead trees were cleared and buried, and new plantations established a few years later. Today, more than three decades later, gamma and beta-radiation near the ChNPP is still elevated compared with ambient levels but have decreased by a factor of 300 and 100, respectively. In the present work, Scots pine-trees growing at High (220 μGy h-1), Medium (11 μGy h-1), and Low (0.2 μGy h-1) total (internal + external) dose rates of chronically elevated ionising radiation in the Chernobyl Exclusion zone were investigated with respect to possible damage to DNA, cells and organelles, as well as potentially increased levels of phenolic and terpenoid antioxidants. Scots pine from the High and Medium radiation sites had elevated levels of DNA damage in shoot tips and needles as shown by the COMET assay, as well as increased numbers of resin ducts and subcellular abnormalities in needles. Needles from the High radiation site showed elevated levels of monoterpenes and condensed tannins compared with those from the other sites. In conclusion, more than three decades after the ChNPP accident substantial DNA damage and (sub)cellular effects, but also mobilisation of stress-protective substances possessing antioxidant activity were observed in Scots pine trees growing at elevated levels of ionising radiation. This demonstrates that the radiation levels in the Red Forest still significantly impact the plant community.
... Existe además muy poca variación respecto al número de canales, solamente se observa un pequeño aumento hacia la parte alta, la cual se comporta como la parte más seca debido a las fuertes exposiciones al sol y al viento. En estudios preliminares se ha detectado que la mayor densidad de canales se asocia a áreas de menor disponibilidad de humedad ISSN: 1996-2452RNPS: 2148Revista CFORES, enero-abril 202311(1) (Jankowski et al. 2017(Jankowski et al. , 2019 y su incremento en número y tamaño está correlacionado en Pinus yunnanensis con disminuciones de la precipitación y aumento de la temperatura, que contribuyen a reducir la influencia de la extrema sequía y el calor (Huang et al. 2016). ...
Variations in the structure of plant leaves are mainly due to environmental variability. In many cases the way to acclimatize to unfavorable conditions. It is documented that in Cuba the anatomical and morphological characteristics of P. caribaea needles differ between ecotopes with different edaphoclimatic conditions. In this study, the effect of the position in the tree crown on the anatomy of the needles is analyzed. For this purpose, needles were collected from the lower, middle and upper part of 30 trees. The variables analyzed were thickness of the chlorophyll parenchyma, thickness of the transfusion parenchyma, height of the conduction tissue and width of the conduction tissue, cuticle thickness, epidermis thickness, hypodermis thickness, number of layers of hypodermis cells, number of channels and number of stomat. The results of the analyzes show a greater differentiation of the morphology of the needles towards the upper part of the tree, which is expressed by the increase in the thickness of the protective tissues and related to the greater exposure to the sun and lower relative humidity than they are exposed. The variables that contribute the most to differentiate the needles according to their position in the tree are the number of stomata and the number of cells in the hypodermis.
... Our results are in agreement with a number of studies showing that abiotic factors, such as climate conditions, affect not only morphological and anatomical characteristics of P.nigra needles (Schoettle and Rochelle 2000;Jankowski et al. 2017), but also geographical distribution of the species (Niinemets et al. 2001;Urbaniak et al. 2003;Pensa et al. 2004). Similarly, studying morpho-anatomical structure of P.heldreichii needles in two natural populations situated in Serbia and North Macedonia, Nikolić et al. (2019) reported that population from Serbia was characterized by significantly shorter, but wider and with narrower resin ducts. ...
In this paper the variability of morphological (needle length and needle width) and anatomical (resin ducts width, epidermis thickness, hypodermis height, number of the hypodermis layers and needle thickness) properties of Pinus nigra J.F. Arnold (black pine) needles were studied at the intra-and inter-population levels. Two mountains in Serbia, Jastrebac and Goč, were selected as experimental plots. Three Pinus nigra trees were selected from both localities (6 in total). Obtained results showed that trees on Goč had bigger dimensions of the following elements: needle length, slightly wider needle width, epidermis thickness, hypodermis height, number of hypodermis layers and needle thickness. On the other hand, resin ducts were only slightly wider by the trees from Jastrebac. The results of the analysis of variance showed that variation between studied populations, as well as variation between trees within populations was statistically significant for all needle traits except resin ducts width and hypodermis height.
... It has been estimated that the needles of pine trees that died were exposed (Lombardero et al. 2002). In Scots pine, however, the size of resin ducts was shown to increase 129 with decreasing winter temperature, but no correlation between the number of resin ducts and the 130 winter temperature was observed (Jankowski et al. 2017 Table 2). The total monoterpene concentration (ng g -1 ) were more than 100 % higher 389 in samples from the High radiation site compared with the two other sites, while there were no 390 significant differences in sesquiterpene contents (Figure 8). ...
... It has been detected that the higher density of resin canals is associated with areas of lower moisture availability (Jankowski & al. 2017(Jankowski & al. , 2019 and their increase in number and size is correlated in P. yunnanensis with the decrease in precipitation and increase in temperature that contributes to reduce the influence of extreme drought and heat (Huang & al. 2016) similar to what was found in this species. On the other hand, it has been documented, in P. pinaster Ait., the close relationship between sites very poor in nutrients, especially with low phosphorus content, with increases in number and diameter of the carcass and resin production (Sampedro & al. 2011, Moreira & al. 2015. ...
The variation of anatomical traits is crucial to assess ecological adaptability, so important for forest management and the conservation of endemic species. Pinus tropicalis is an endemic species distributed mainly in the province of Pinar del Río, Cuba. It occupies a great variety of ecotopes in continuous pure populations or in sympatry with Pinus caribaea var. caribaea. The objective of this study is to determine the anatomical variation of Pinus tropicalis needles as an adaptive differential response to environmental conditions determined by lithology, altitude and slope. Twenty to thirty individuals were sampled from all the ecotopes where the species grows naturally. Cross sections were made from 10 needles of each tree and 12 anatomical variables were evaluated. The results of the statistical analysis revealed significant differences between ecotopes, mainly in quartzite sands with high silica content. The principal component analysis showed a relationship between anatomical variables related to water economy and assimilation. The discriminant distinguished groups defined from the relationship of the anatomical variables with the lithology. The variables that contributed the most to discriminate between ecotopes were those related to water regulation, the number and diameter of the resin canals, and the thickness of the cuticle. The availability of water and the oligotrophic substrates are the factors that influence anatomical variation. The results are a contribution to ecology and silvicultural management of the species.
... The standard deviation of the ice freeze-thaw rate is only 0.00405 (Table 3), indicating that over winter evergreen coniferous trees are able to regulate themselves more effectively than deciduous broadleaf trees. Further, they are able to regulate their water-ice content more effectively [5,41], adapt better to the overwintering environment, and have better cold resistance [42][43][44]. ...
Advancements in detection instruments have enabled the real-time acquisition of water information during plant growth; however, the real-time monitoring of freeze–thaw information during plant overwintering remains a challenge. Based on the relationship between the change in the water–ice ratio and branch impedance during freezing, a miniature noninvasive branch volume ice content (BVIC) sensor was developed for monitoring real-time changes in volumetric ice content and the ice freeze-thaw rate of woody plant branches during the overwintering period. The results of the performance analysis of the impedance measurement circuit show that the circuit has a lateral sensitivity range, measurement range, resolution, measurement accuracy, and power consumption of 0–35 mm, 0–100%, 0.05%, ±1.76%, and 0.25 W, respectively. The dynamic response time was 0.296 s. The maximum allowable error by the output voltage fluctuation, owing to the ambient temperature and humidity, was only ±0.635%, which meets the actual use requirements. The calibration curve fit coefficients were >0.98, indicating a significant correlation. The ice content of plant branches under cold stress was measured for indoor and field environments, and the sensors could effectively monitor changes in the branch ice content in plants exposed to cold stress. Additionally, they can differentiate between plants with different cold resistances, indicating the reliability of the BVIC sensor.
... These observations indicated that the frost resistance of P. densiflora needles was not achieved by increasing cell sap concentration. Needles from cold sites have wider resin ducts that account for a larger proportion of needle volume than the needles from warmer sites [41,42]. Lipid synthesis in needles of Sitka spruce was significantly promoted during cold acclimation [43]. ...
Overwintering and spring recovery of pine needles have important ecological significance. The natural changes in physiological state, photosynthetic function, and material metabolism in needles of Pinus densiflora Siebold & Zucc. from the autumn of 2020 to the spring of 2021 were assessed. The photosynthetic rate (Pn) of P. densiflora needles decreased first and then increased, with the maximum Pn observed in the autumn. After experiencing sub-zero temperatures in the winter, needles of P. densiflora still performed weak photosynthesis at a temperature above zero. In the spring, the Pn gradually recovered but could not recover to the maximum. Under sub-zero temperatures in the winter of 2020, the plasma membrane permeability and MDA content of needles increased, whereas the chlorophyll content and Fv/Fm decreased significantly. The needles showed obvious characteristics of freezing injury. During the whole process, the water content of needles remained at a low level (about 60%), which gradually decreased with the increase of leaf age. The cell sap concentration and soluble sugar content of needles decreased with the decrease in air temperature and recovered in spring. Therefore, P. densiflora needles do not improve frost resistance through osmotic adjustment. However, the increasing carotenoid content is helpful for needles to tide over the winter. The soluble sugar and protein contents increased, implying they are important for the recovery of needles in spring. This study expands our understanding of the mechanism and ecological contribution of overwintering and spring recovery of pine needles.
... (Huang & al. 2016 Arenas cuarcíticas-llanuras bajas-terrenos llanos, AcS-LLB-Tll: Arenas cuarcíticas con sílice-llanuras bajas-terrenos llanos, AP-SM-Tli: Areniscas polimícticas-submontaña-ligeramente inclinados, AG-ALM-Tfi: Areniscas grises-alturas medias-terrenos fuertemente inclinados, AG-ALM-LI: Areniscas grises-alturas medias-ligeramente inclinados, AG-LLM-Tfi: Areniscas grises-llanuras medias-terrenos fuertemente inclinados, AG-SM-Tfi: Areniscas grises-submontañas-terrenos fuertemente inclinados, RV-LLB-TIl: Sedimentos vegetales-llanuras bajas-terreno llano. Se ha detectado que la mayor densidad de canales de resina se asocia a áreas menos húmedas (Jankowski & al. 2017(Jankowski & al. , 2019 y su incremento en número y tamaño en P. yunnanensis está correlacionado con la disminución de la precipitación y el aumento de la temperatura; lo que contribuye a reducir la influencia de la extrema sequía y el calor (Huang & al. 2016), similar a lo encontrado en esta especie. Por otro lado, se ha documentado en P. pinaster una relación estrecha entre sitios muy pobres en nutrientes, en especial con bajos contenidos de fósforo, con incrementos en número y diámetro del canal y la producción de resina (Sampedro & al. 2011, Moreira & al. 2015. ...
Los artículos de acceso abierto publicados en la Revista del Jardín Botánico Nacional se distribuyen según regulaciones de Creative Commons Attribution 4.0 International licence (CC BY 4.0-Variación anatómica foliar en poblaciones naturales de Pinus tropicalis en Pinar del Río, Cuba RESUMEN La variación de los caracteres anatómicos es crucial para evaluar la adaptabilidad ecológica, la cual reviste gran importancia para el manejo forestal y la conservación de especies endémicas. Pinus tropicalis es un árbol endémico distribuido por la provincia Pinar del Río y la Isla de la Juventud, Cuba. Ocupa gran variedad de ecótopos en poblaciones puras o en simpatría con P. caribaea var. caribaea. El objetivo de este estudio fue evaluar la variación anatómica de las acículas de P. tropicalis como respuesta diferencial adaptativa a las condiciones ambientales determinadas por la litología, la altitud y la pendiente. Se muestrearon de 20 a 30 individuos de todos los ecótopos donde crece la especie naturalmente. Se realizaron cortes transversales a 10 acículas de cada árbol y se evaluaron 12 variables anatómicas. Los resultados de los análisis estadísticos revelaron diferencias significativas entre individuos de los ecótopos, fundamentalmente en las arenas cuarcíticas con alto contenido de sílice. El análisis de componentes principales mostró una relación entre variables anatómicas relacionadas con la economía hídrica y la asimilación. El discriminante distinguió grupos definidos a partir de la relación de las variables anatómicas con la litología. Las variables que más contribuyeron a discriminar entre ecótopos fueron las relacionadas con la regulación hídrica, el número y diámetro de los canales de resina y el grosor de la cutícula. La disponibilidad de agua y la oligotrofia de los sustratos son los factores que más influyeron en la variación anatómica. Los resultados son una contribución a la ecología y la silvicultura de la especie. Palabras clave: adaptación, análisis multivariado, diferenciación anatómica ABSTRACT The variation of anatomical traits is crucial to assess ecological adaptability, which is of great importance for forest management and the conservation of endemic species. Pinus tropicalis is an endemic tree distributed in the province of Pinar del Río and Isla de la Juventud, Cuba. It occupies a great variety of ecotopes in continuous pure adaptability populations or in sympatry with Pinus caribaea var. caribaea. The objective of this study was to evaluate the anatomical variation of Pinus tropicalis needles as an adaptive differential response to environmental conditions determined by lithology, altitude and slope. Twenty to thirty individuals were sampled from all the ecotopes where the species grows naturally. Cross sections were made from 10 needles of each tree and 12 anatomical variables were evaluated. The results of the statistical analysis revealed significant differences between ecotopes, mainly in quartzite sands with high silica content. The principal component analysis showed a relationship between anatomical variables related to water economy and assimilation. The discriminant distinguished groups defined from the relationship of the anatomical variables with the lithology. The variables that contributed the most to discriminate between ecotopes were those related to water regulation, the number and diameter of the resin channels, and the thickness of the cuticle. The availability of water and the oligotrophic substrates are the factors that influence anatomical variation. The results are a contribution to ecology and silvicultural management of the species.
... Chen et al. (2014) stated that LMA can be expressed as a linear function of light, and it reaches about 12.64 mg cm −2 for conifer species when light is above ca 30%. A higher value of LMA has also been found in shorter and long-lived needles of pines as a result of an adaptation to a cold environment (Jankowski et al. 2017). LMA values for the studied populations and regions are in the LMA ranges given for conifers, in accordance with the literature. ...
Tree provenance trials are believed to be a valuable tool for assessing the adaptive potential of a population to a changing environment and ultimately for predicting the populations that are best adapted to global warming. Here, the phenotypic plasticity of morphometric traits of needles and lateral shoots of pines growing in a provenance plot in central Poland was examined to assess the inter- and intra-population variability. No significant differences were found in the measured and counted morphometric features, i.e., needle length (NL), cumulative needles length (CNL), thickness (ST), volume (SV) and shoot density (SD), number of needles per 5 cm fragment of shoot (NN), dry weight of needles (NDW) and shoot (SDW), thickness of bark (BT) and wood (WT), pith diameter (PD), and needle dry mass per area (LMA) among three pine populations while accounting for their region of origin (inter-population variability). In terms of the above-mentioned features, individual populations differed significantly from each other, except for NN and ST. We also noticed a positive, significant relationship between LMA and ST in all studied populations and based on Euclidean distances of measurable or counted traits, three population groups were identified. We concluded that LMA, which is commonly used to quantify leaf structure, is helpful in differentiating intra-population variability.
... Although LMA generally increases across species in more arid environments, the relationship is fairly weak (Reich 2014), likely because considerable variation exists among species and clades that have evolved to fill different niches within a community in any given habitat (Bruelheide et al. 2018, Treurnicht et al. 2020. As with plants that experience drought stress, plants adapted to colder annual temperatures also tend to produce leaves with higher LMA (Niinemets 2016, Jankowski et al. 2017). However, whether higher LMA is also associated with a greater number of FT cycles or how this trait may vary intraspecifically across the FT and drought poly-stress gradient is unknown. ...
Conifers inhabit some of the most challenging landscapes where multiple abiotic stressors (e.g., aridity, freezing temperatures) often co-occur. Physiological tolerance to multiple stressors ('poly-tolerance') is thought to be rare because exposure to one stress generally limits responses to another through functional trade-offs. However, the capacity to exhibit poly-tolerance may be greater when combined abiotic stressors have similar physiological impacts, such as the disruption of hydraulic function imposed by drought or freezing. Here, we reviewed empirical data in light of theoretical expectations for conifer adaptations to drought and freeze-thaw cycles with particular attention to hydraulic traits of the stem and leaf. Additionally, we examined the commonality and spatial distribution of poly-stress along indices of these combined stressors. We found that the locations with the highest values of our poly-stress index are characterized by moderate drought and moderate freeze-thaw, and most of the global conifer distribution occupies areas of moderate poly-stress. Among traits examined, we found diverse responses to the stressors. Turgor loss point (TLP) did not correlate with freeze-thaw or drought stress individually, but did with the poly-stress index, albeit inverse to what was hypothesized. Leaf mass per area was more strongly linked with drought stress than the poly-stress, and not at all with freeze-thaw stress. In stems, the water potential causing 50% loss of hydraulic conductivity became more negative with increasing drought- and poly-stress, but did not correlate with freeze-thaw stress. For these traits, we identified a striking lack of coverage for substantial portions of species ranges, particularly at the upper boundaries of their respective poly-stress indices, demonstrating a critical gap in our understanding of trait prevalence and plasticity along these stress gradients. Future research should investigate traits that confer tolerance to both freeze-thaw and drought stress in a wide range of species across broad geographic scales.
Highlights:
... Special methods are necessary to account statistically for the complex data structure represented by a phylogenetic tree reasons why pine needles are shorter and broader in cold climate than under warmer conditions are still conjectural. Suggestions comprise freezing (Kaku and Salt 1968), snow load or growth conditions (Jankowski et al. 2017). To cut a long story short, there was no evidence for special surface traits or other adaptations conveying superior fog harvesting abilities to needles of P. canariensis, and their long thin shape is a general trait in needles of pine species which live in warm and frost-free habitats. ...
Bio-inspired design (BID) means the concept of transferring functional principles from biology to technology. The core idea driving BID-related work is that evolution has shaped functional attributes, which are termed “adaptations” in biology, to a high functional performance by relentless selective pressure. For current methods and tools, such as data bases, it is implicitly supposed that the considered biological models are adaptations and their functions already clarified. Often, however, the identification of adaptations and their functional features is a difficult task which is not yet accomplished for numerous biological structures, as happens to be the case also for various organismic features from which successful BID developments were derived. This appears to question the relevance of the much stressed importance of evolution for BID. While it is obviously possible to derive an attractive technical principle from an observed biological effect without knowing its original functionality, this kind of BID (“analog BID”) has no further ties to biology. In contrast, a BID based on an adaptation and its function (“homolog BID”) is deeply embedded in biology. It is suggested that a serious and honest clarification of the functional background of a biological structure is an essential first step in devising a BID project, to recognize possible problems and pitfalls as well as to evaluate the need for further biological analysis.
... The StFTRI corresponding to Juniperus virginiana L. in Fig. 7 is also small, and the standard deviation of the StFTRI is only 0.00405 ( Table 2), indicating that evergreen coniferous species are more capable of regulating themselves during the overwintering period than the deciduous broadleaf species [5,22]. Therefore, Juniperus virginiana L. (evergreen coniferous species) is more resistant to cold because of its ability to regulate the ice-water content e ciently and adapt to the overwintering conditions [23,24]. ...
Background: Frost stress is an abiotic stressor for plant growth that impacts the health and the regional distribution of plants. The freeze-thaw characteristics of plants during the overwintering period help to understand relevant issues in plant physiology, including plant cold resistance and cold acclimation. Therefore, we aimed to develop a non-invasive instrument and method for accurate in situ detection of changes in stem freeze-thaw characteristics during the overwintering period.
Results: A sensor was designed based on standing wave ratio method (SWR) to measure stem volume water content (StVWC). We were able to measure stem volume ice content (StVIC) and stem freeze-thaw rate of ice (StFTRI) during the overwintering period. The resolution of the StVWC sensor is less than 0.05 %, the mean absolute error and root mean square error are less than 1 %, and the dynamic response time is 0.296 s. The peak point of the daily change rate of the lower envelope of the StVWC sequence occurs when the plant enters and exits the overwintering period. The peak point can be used to determine the moment of freeze-thaw occurrence, whereas the time point corresponding to the moment of freeze-thaw coincides with the rapid transition between high and low ambient temperatures. In the field, the StVIC and StFTRI of Juniperus virginiana L., Lagerstroemia indica L. and Populus alba L. gradually increased at the beginning, fluctuated steadily during, and then gradually decreased by the end of the overwintering period. The StVIC and StFTRI also showed significant variability due to differences among the tree species and latitude.
Conclusions: The StVWC sensor has good resolution, accuracy, stability, and sensitivity. The envelope changes of the StVWC sequence and the correspondence between the freeze-thaw moment and the ambient temperature indicate that the determination of the freeze-thaw moment based on the peak point of the daily change rate of the lower envelope is reliable. The results show that the sensor is able to monitor changes in the freeze-thaw characteristics of plants and effectively characterize freeze-thaw differences and cold resistance of different tree species. Furthermore, this is a cost-effective tool for monitoring freeze-thaw conditions during the overwintering period.
... For instance, species within subgroup TMVB (A. religiosa, A. flinckii and A. jaliscana) have contrasting cone and needle morphologies (Cruz-Nicolás et al., 2020;Vázquez-García et al., 2014), are distributed at different elevation zones (Cuevas-Guzmán et al., 2011), and exhibit non-overlapping pollen production times (Mantilla-Blandón, 2006). Similarly, A. hickelii and A. hidalgensis are the only two Mesoamerican firs that have more than two resin canals, a putatively adaptive trait against herbivores, or which could be related to drought stress (Huang et al., 2016;Jankowski et al., 2017;López et al., 2010). Whether or not these differences are the result of character displacement after secondary contact is still a hypothesis to test. ...
Constructing phylogenetic relationships among closely related species is a recurrent challenge in evolutionary biology, particularly for long-lived taxa with large effective population sizes and uncomplete reproductive isolation, like conifers. Conifers further have slow evolutionary rates, which raises the question of whether adaptive or non/adaptive processes were predominantly involved when they rapidly diversified after migrating from temperate regions into the tropical mountains. Indeed, fine-scale phylogenetic relationships within several conifer genus remain under debate. Here, we studied the phylogenetic relationships of endemic firs (Abies, Pinaceae) discontinuously distributed in the montane forests from the Southwestern United States to Guatemala, and addressed several hypotheses related to adaptive and non-adaptive radiations. We derived over 80K SNPs from genotyping by sequencing (GBS) for 45 individuals of nine Mesoamerican species to perform phylogenetic analyses. Both Maximum Likelihood and quartets-inference phylogenies resulted in a well-resolved topology, showing a single fir lineage divided in four subgroups that coincided with the main mountain ranges of Mesoamerica; thus having important taxonomic implications. Such subdivision fitted a North-South isolation by distance framework, in which non-adaptive allopatric processes seemed the rule. Interestingly, several reticulations were observed within subgroups, especially in the central-south region, which may explain past difficulties for generating infrageneric phylogenies. Further evidence for non-adaptive processes was obtained from analyses of 21 candidate-gene regions, which exhibited diminishing values of πa/πs and Ka/Ks with latitude, thus indicating reduced efficiency of purifying selection towards the Equator. Our study indicates that non-adaptive allopatric processes may be key generators of species diversity and endemism in the tropics.
... Some research also focused on the correlations between anatomical structures and needle length. For example, Apple et al. (2000) reported that longer needles of young saplings of Douglas Fir often had smaller vascular cylinders, larger resin canals and few hypodermal cells; Jankowski et al. (2017) found that needle length of Pinus sylvestris was weakly correlated with needle cross-sectional area and not at all with LMA, width or thickness. However, the correlations between needle anatomy with needle length have been seldom reported before in Picea. ...
The genus Picea has wide geographical range and includes species with great economic and ecological value in the northern hemisphere. Growth traits, gas exchange parameters and needle morphology and anatomy vary greatly among Picea species, but the instrinsic relationship among these traits has not been well studied for the genus Picea. We thus conducted a common garden experiment to study the relationship for these traits in 13 native and 4 exotic Picea species growing at an experimental site in Tianshui, Gansu, China. Nearly all of these traits were significantly different among the 17 species and most traits were under relatively strong genetic control. The four species introduced from abroad (P. abies, P. pungens, P. glauca and P. mariana) exhibited good growth performance in the experimental site. We found that the growth traits showed significantly positive correlation with branching characteristics. Moreover, the species with good growth performance had a relatively high photosynthetic rate. The correlation analysis based on needle morphological and anatomical traits revealed that needle traits were interrelated and needle anatomical traits might be impacted by needle size due to the increase of mesophyll area and central cylinder area with needle length. Furthermore, the relationship between needle structures and gas exchange parameters may indicate that a higher photosynthetic rate can be attributed to variations in needle structures. In addition, both the cluster analysis and principal component analysis based on needle morphology, anatomy, gas exchanges and growth traits might partially reflect the evolutionary history of the 17 Picea species. Our study represents a comprehensive survey of variation within the genus Picea to date and opens new avenues for exploring the instrinsic relationship among growth traits, needle gas exchange and needle morphology and anatomy.
... Consequently, the role of endogenous sugars in increasing resistance to low temperatures is uncertain, but there is an interesting approach to exogenous Suc enrichment with the aim of disclosing mechanisms, whose regulation depends on the carbohydrate status and contributes to increasing cold resistance (Deryabin et al., 2011). The adaptive nature of leaf variability has been demonstrated by comparative structural and functional studies of foliar traits driven by environmental characteristics (Wyka et al., 2007;Niinemets 2015;Jankowski et al., 2017). Under natural conditions, low temperatures of atmospheric air and the surface layer of the soil dominate in the early spring. ...
... Consequently, the role of endogenous sugars in increasing resistance to low temperatures is uncertain, but there is an interesting approach to exogenous Suc enrichment with the aim of disclosing mechanisms, whose regulation depends on the carbohydrate status and contributes to increasing cold resistance (Deryabin et al., 2011). The adaptive nature of leaf variability has been demonstrated by comparative structural and functional studies of foliar traits driven by environmental characteristics (Wyka et al., 2007;Niinemets 2015;Jankowski et al., 2017). Under natural conditions, low temperatures of atmospheric air and the surface layer of the soil dominate in the early spring. ...
The effects of sucrose (Suc) on the ultrastructure of photosynthetic apparatus (PSA) and its functional characteristics were investigated in chilling-tolerant Snowdrop (Galanthus nivalis L.). On the first stage of the experiments, the plants were acclimated at +5 °C and then their detached leaves were subjected to low temperatures (–5 or –15 °C) in the presence of Suc (0.02 or 0.1 M). The electron microscopic analysis showed that Suc treatment at +5 °C induced granal thylakoid elongation and reduction of number of thylakoids. At negative temperatures, the number of thylakoids per granum and the height of grana increased after Suc treatment. The data obtained by method of slow induction chlorophyll fluorescence showed that sharp drop in functional parameters (Fv/Fm, qP, and ETR) with decrease in temperature from +5 to –15 °C was prevented in part by treating of leaves with 0.02 M Suc and, to a large extent, after exposure of leaves in 0.1 M Suc solution. Non-photochemical quenching of fluorescence increased with decrease in the temperature to –15 °C and stabilized with Suc-treatment. The effect of Suc on G. nivalis PSA ultrastructure and functioning suggests that their chloroplasts are capable of osmotic adjustment in response to cold stress.
... There are many other reports from a wide range of tree species of substantial plastic changes in developing leaves in response to the environmental circumstances under which the trees developed or changes in light availability and/or water stress at different heights in the forest canopy. Characteristics such as leaf size, shape, venation, petiole thickness and leaf mass area, stomatal characteristics, cellular type and arrangement, leaf arrangement on shoots and shoot structure have all been found to vary substantially (Schoettle 1994;Niinemets 1999bNiinemets , 2001Niinemets et al. , 2005Niklas 1999;Richardson et al. 2000;Greenwood et al. 2008;Ambrose et al. 2009;Räim et al. 2012;Ishii et al. 2014;Osada et al. 2014;Azuma et al. 2016;Binks et al. 2016a, b;Fellner et al. 2016;Cavaleri 2014, 2017;Jankowski et al. 2017;de la Riva et al. 2018;Domingues et al. 2018;He et al. 2018;Kawai and Okada 2018;Kiorapostolou et al. 2018;Kuusk et al. 2018a, b;Zhang et al. 2018a, b). In many of these papers, it is argued that these changes are consistent with compensatory mechanisms to maintain photosynthetic capacity of the canopy. ...
Once forests have achieved a full canopy, their growth rate declines progressively with age. This work used a global data set with estimates from a wide range of forest types, aged 20‒795 years, of their annual photosynthetic production (gross primary production, GPP) and subsequent above- plus below-ground biomass production (net primary production, NPP). Both GPP and NPP increased with increasing mean annual temperature and precipitation. GPP was then unrelated to forest age whilst NPP declined progressively with increasing age. These results implied that autotrophic respiration increases with age. It has been proposed that GPP should decline in response to increasing water stress in leaves as water is raised to greater heights as trees grow taller with age. However, trees may make substantial plastic adjustment in morphology and anatomy of newly developing leaves, xylem and fine roots to compensate for this stress and maintain GPP with age. This work reviews the possibilities that NPP declines with age as respiratory costs increase progressively in, any or all of, the construction and maintenance of more complex tissues, the maintenance of increasing amounts of live tissue within the sapwood of stems and coarse roots, the conversion of sapwood to heartwood, the increasing distance of phloem transport, increased turnover rates of fine roots, cost of supporting very tall trees that are unable to compensate fully for increased water stress in their canopies or maintaining alive competitively unsuccessful small trees.
... Likewise, the increase in relative duct area with increasing elevation (and therefore lower air temperature; [57]), is similar to the linear relationship between relative duct area in needles and minimum air temperature in Scots pine (P. sylvestris L.) [58] yet different from the curvilinear response of needle duct traits to elevation of P. taiwanensis Hayata [59]. Limber pine invests more in resin duct defenses per unit radial wood growth with increasing elevation, however, resin flow is better predicted by resin duct number and area [24] which decreased in our study with increasing elevation. ...
Limber pine (Pinus flexilis James) co-evolved with the mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) and is now also challenged by the non-native pathogen Cronartium ribicola (J.C. Fisch.) that causes the lethal disease white pine blister rust (WPBR). Previous research suggests that trees infected with WPBR can be preferred hosts for MPB. Using resin duct traits associated with MPB resistance, we tested for a relationship between resistance to MPB and WPBR in limber pine, in the absence of either biological agent. These analyses will help evaluate if MPB historically may have contributed to natural selection for WPBR resistance in advance of WPBR invasion, and could help explain the unusually high frequency of the dominant Cr4 allele for complete resistance to WPBR in limber pine populations of the Southern Rocky Mountains. Resin duct production, density and relative duct area did not differ between healthy trees previously inferred to carry the dominant Cr4 allele and trees that lack it at 22 sites, though some duct traits varied with elevation. MPB resistance does not appear to have played an evolutionary role in contributing to the high frequency of Cr4 in naïve populations, however, MPB may affect the future evolution of resistance to WPBR in the pines where the two pests coincide and WPBR will affect forest recovery after MPB epidemics. MPB-WPBR interactions in a changing climate will affect the future trajectory of limber pine.
... Consequently, the role of endogenous sugars in increasing resistance to low temperatures is uncertain, but there is an interesting approach to exogenous Suc enrichment with the aim of disclosing mechanisms, whose regulation depends on the carbohydrate status and contributes to increasing cold resistance (Deryabin et al., 2011). The adaptive nature of leaf variability has been demonstrated by comparative structural and functional studies of foliar traits driven by environmental characteristics (Wyka et al., 2007;Niinemets 2015;Jankowski et al., 2017). Under natural conditions, low temperatures of atmospheric air and the surface layer of the soil dominate in the early spring. ...
The effects of sucrose (Suc) on the ultrastructure of photosynthetic apparatus (PSA) and its functional characteristics were investigated in chilling-tolerant Snowdrop (Galanthus nivalis L.). On the first stage of the experiments, the plants were acclimated at +5 °C and then their detached leaves were subjected to low temperatures (–5 or –15 °C) in the presence of Suc (0.02 or 0.1 M). The electron microscopic analysis showed that Suc treatment at +5 °C induced granal thylakoid elongation and reduction of number of thylakoids. At negative temperatures, the number of thylakoids per granum and the height of grana increased after Suc treatment. The data obtained by method of slow induction chlorophyll fluorescence showed that sharp drop in functional parameters (Fv/Fm, qP, and ETR) with decrease in temperature from +5 to –15 °C was prevented in part by treating of leaves with 0.02 M Suc and, to a large extent, after exposure of leaves in 0.1 M Suc solution. Non-photochemical quenching of fluorescence increased with decrease in the temperature to –15 °C and stabilized with Suc-treatment. The effect of Suc on G. nivalis PSA ultrastructure and functioning suggests that their chloroplasts are capable of osmotic adjustment in response to cold stress.
Species-specific anatomical and morphological characteristics of Pinus sylvestris and Larix sibirica needles were studied at different levels of tree stand pollution by aluminum smelter emissions. The anatomical characteristics of the needle were studied using light microscopy. The level of tree stand pollution was determined using the cluster analysis outcomes of the pollutant elements content (fluorine, sulfur, and heavy metals) in the needles. Four levels of tree stand pollution were separated: low, moderate, high, and critical, as well as background tree stand in unpolluted areas. It was found that the state of tree phytomass deteriorated with increasing levels of pollution (from low to critical): pine crown defoliation increased to 85%, and larch defoliation increased to 65%. The life span of pine needles was reduced to 2–3 years, with a background value of 6–7 years. The change of morphological parameters was more pronounced in P. sylvestris: the weight and length of the 2-year-old shoot decreased by 2.7–3.1 times compared to the background values; the weight of needles on the shoot and the number of needle pairs on the shoot—by 1.9–2.1 times. The length of the needle and shoot and the number of L. sibirica brachyblasts decreased by 1.8–1.9 times. The anatomical parameters of the needle also changed to a greater extent in P. sylvestris. Up to the high level of tree pollution, we observed a decrease in the cross-sectional area of the needle, central cylinder, vascular bundle, area and thickness of mesophyll, number and diameter of resin ducts by 18–66% compared to background values. At the critical pollution level, when the content of pollutant elements in pine needles reached maximum values, the anatomical parameters of the remaining few green needles were close to background values. In our opinion, this may be due to the activation of mechanisms aimed at maintaining the viability of trees. A reduction in thickness and area of assimilation tissue in the L. sibirica needle was detected only at the critical pollution level. An upward trend in these parameters was found at low, medium, and high pollution levels of tree stand, which may indicate an adaptive nature. The results suggested that at a similar pollution level of trees, the greatest amount of negative anatomical and morphological changes were recorded in pine needles, which indicates a greater sensitivity of this species to technogenic emissions.
Citation: Yang, Y.; Hu, M.; Fan, M.; Wang, L.; Lv, T.; Zhang, H.; Xu, K.; Duan, Y.; Fang, Y. Inter-and
Global climate change has been seen to result in marked impacts on forest ecosystems such as accelerated tree mortality worldwide due to incidental hydraulic failure caused by intensified and more frequent occurrence of extreme drought and heat-waves. However, it is well understood how the tree hydrological strategies would adjust to environmental variability brough about by climate changes. Here we investigated the hydraulic adjustment as a mechanism of acclimation to different climate conditions along an altitudinal gradient in Faxon fir (Abies fargesii var. faxoniana) ― a tree species that plays a key role in conservation of wildlife and maintenance of ecosystem services in subalpine forests. The hydraulic traits and selective morphological and physiological variables were measured seasonally along an altitudinal gradient from 2,800 to 3,600 m a.s.l. We found that the native percentage loss of conductivity (PLC) increased with altitude across the seasonal measurements. Both the native sapwood-specific hydraulic conductivity (Ks) and native leaf-specific hydraulic conductivity (Kl) significantly decreased with altitude for measurements in July and October, coinciding with the timing for peak growth and pre-dormancy, respectively. The morphological traits varied toward more conservative tree hydrological strategies with increases in altitude, exhibiting trade-offs with hydraulic traits. The total non-structural carbohydrates in both needle (NSCNeedle) and branch (NSCBranch) as well as photosynthetic capacity of current-year leaves played variable roles in maintaining the integrity of the hydraulic functioning and shaping the hydraulic adjustment under prevailing environmental conditions. Our findings indicate that Faxon fir possesses some degree of hydraulic adaptability to water limitation imposed by climate fluctuations in subalpine region through morphological and physiological modifications.
Many studies have reported intraspecific variations in leaf functional traits, but their contribution to plant performance and ecosystem function are poorly understood. We studied altitudinal gradients of intraspecific variations in leaf traits, productivity and resource use efficiency in the dominant species of subalpine evergreen coniferous and deciduous broad‐leaved forests in Japan.
We addressed three hypotheses, which are exclusive to each other. (1) Leaf traits vary along the leaf economics spectrum (LES). Plants that grow at lower and higher altitudes have fast‐ and slow‐return strategies, respectively, which improve productivity or resource use efficiency in the respective habitat. (2) Leaf trait variations are not consistent with the LES, but they contribute to improving productivity or resource use efficiency in the respective habitat. (3) Leaf trait variations do not contribute to improving productivity or resource use efficiency at higher altitudes.
On the studied mountain range, Fagus crenata, a deciduous broad‐leaved tree, and Abies mariesii, an evergreen conifer, are the dominant species at lower and higher altitudes respectively. In F. crenata, leaf mass per area (LMA) and nitrogen concentrations were higher at higher altitudes. The net assimilation rate and light use efficiency during the growing season were greater at higher altitudes, which compensated for the shorter growing season in terms of annual productivity. In A. mariesii, the LMA was lower and the leaf life span was unchanged at higher altitudes. Productivity and resource use efficiency decreased with altitude.
Synthesis. We conclude that F. crenata improves its productivity and resource use efficiency at higher altitudes by altering its leaf functional traits (Hypothesis 2), whereas alterations to leaf traits in A. mariesii are not associated with any improvement at higher altitudes (Hypothesis 3), which may result from the negative impact of environmental stress. Hence, the ecological significance of altitudinal variations in leaf traits depends on species and environment.
Intraspecific variability of anatomical leaf traits is usually determined on the basis of median sections and interpreted as adaptive. We hypothesized that anatomical traits may relate to the position within the leaf, reflecting functional coordination e.g., between transport and gas exchange capacities and between supporting tissue and the supported leaf weight. Anatomical variation may thus be partly controlled by leaf size. We examined variability of transverse anatomical traits and stomata at different positions along the leaf axis using Scots pine (Pinus sylvestris L.) needles collected from three geographical locations with contrasting climate (Poland, Southern and Northern Sweden) and differing in length.
Transverse xylem and phloem area, and the number of tracheids at a given cross-section scaled positively with length of the distal needle part and the number of distal stomata. Similarly, the number of vascular sclerenchyma fibers in a cross-section scaled with the length and volume of the distal needle part. Allometric slopes were less steep in the longer, southern-sites needles. Additionally, our study revealed an increased sclerification of epidermis towards the needle apex, the occurrence of widest tracheids in central or subapical regions, a reduced number of resin ducts in basal and apical parts, as well as overall basipetal decreases in duct diameter, the number of stomatal files and stomatal density.
These results show that allometry accounts for significant amount of intraspecific variability in xylem, phloem and fibers, and that environmental adaptation involves also modification of the within-needle allometric relationships. The allometric component of variability, together with the nonlinear distribution of certain traits along needle length, should be considered when designing comparative studies of foliar phenotypes and scaling up from transverse sections to entire needles.
Background: Leaves have highly diverse morphologies. However, with an evolutionary history of approximately 200 million years, leaves of the pine family are relatively monotonous and often collectively called "needles", although they vary in length, width and cross-section shapes. It would be of great interest to determine whether Pinaceae leaves share similar morpho-physiological features and even consistent developmental and adaptive mechanisms.
Results: Based on a detailed morpho-anatomical study of leaves from all 11 Pinaceae genera, we particularly investigated the expression patterns of adaxial-abaxial polarity genes in two types of leaves (needlelike and flattened) and compared their photosynthetic capacities. We found that the two types of leaves share conserved spatial patterning of vasculatures and genetic networks for adaxial-abaxial polarity, although they display different anatomical structures in the mesophyll tissue differentiation and distribution direction. In addition, the species with needlelike leaves exhibited better photosynthetic capacity than the species with flattened leaves.
Conclusions: Our study provides the first evidence for the existence of a conserved genetic module controlling adaxial-abaxial polarity in the development of different Pinaceae leaves.
Interacting stochastic and selective forces drive population and species divergence. Such interaction may generate contrasting clines between genetic and phenotypic factors, which can be related to either geographical or environmental variation depending on the predominant evolutionary force (which in its turn is partly determined by population size). Here, we investigated whether the morphological and genetic differentiation across a species complex in Abies in central Mexico fits isolation by distance (IBD) or isolation-by-adaptation (IBA) frameworks. This complex includes two species (A. religiosa and A. flinckii) with discernible morphological and environmental differences and dissimilar range sizes. After comparing variation at nuclear SSR loci and diagnostic morphological traits of needles with the climate variables contributing to ecological differentiation, we found that the widely distributed A. religiosa has more genetic diversity and is morphologically more heterogeneous than the geographically restricted A. flinckii. Morphological differentiation at three physiologically important traits (needle thickness, number of stomata rows and location of the resin duct) is significantly correlated with geography in A. flinckii (indicative of IBD), but is significantly associated with climate variation in A. religiosa (suggesting IBA). In agreement with quantitative genetics theory, PST (phenotypic differentiation)-G’ST (genetic differentiation) comparisons indicate contrasting contributions of putatively adaptive (A. religiosa) and stochastic (A. flinckii) factors to the morphological differentiation of species related to their population size. The integration of such quantitative genetic/evolutionary aspects may reinforce species descriptions and help in disentangling resilient taxonomic discordance.
Climate change has likely altered high‐latitude forests globally, but direct evidence remains rare. Here we show that throughout a ≈1000‐km transect in Scots pine (Pinus sylvestris L.) forests in Sweden, mature trees in ≈2015 had longer needles with shorter lifetimes than did trees in ≈1915. These century‐scale shifts in needle traits were detected by sampling needles at 74 sites from 2012 to 2017 along the same transect where needle traits had been assessed at 57 sites in 1914–1915. Climate warming of ≈1 °C all along the transect in the past century has driven this temporal shift in foliage traits known to be physiologically critical to growth and carbon cycling processes. These century‐scale changes in Scandinavian Scots pine forests represent a fingerprint of climate change on a fundamental biological element, the leaf, with repercussions for productivity and sensitivity to future climate, which are likely to be mirrored by similar changes for evergreen conifers across the boreal biome. Direct evidence of the influence of climate change on trees and forests remains scarce. By using contemporary and historical data for Scots pine, we show that from 1915 to 2015 needle longevity has been reduced and needle length has increased everywhere along a temperate–boreal transect, as predicted by fundamental relations of tree traits to the thermal environment.
P. tropicalis is a species endemic to western Cuba, prioritized in Forest Development Plans until 2030. It develops in very contrasting edatopes of white sands and slates, so over the years it must show anatomical differences that allow it to grow. The objective of the study was to characterize the anatomical variation in transversal cuts of the needles of the species in three localities of Pinar del Río. Differences were detected in the anatomical variables of the needles. The variables number of stomas, thickness of the hypodermis and number of resin channels separate San Ubaldo on white sands from the rest. The discriminant analysis shows with 87 % certainty the classification of the cases in each of the collection localities (a priori) and the variables number of stomata, number of channels, cuticle thickness and thickness of hypodermis the most discriminant. Preliminarily it is inferred that soil conditions and water availability influence foliar anatomy.
Plant leaves play a key role in the accumulation of PAHs, as they are able to capture PAHs from the air. In this paper, the mechanism, including absorption and adsorption, for plants to scavenge PAHs from the air was reviewed. Moreover, the differences of PAHs accumulating capability are mainly compared among three representative plant species, including pine needles, Holm oak leaves, and moss. On the whole, it is shown that oak leaves present the strongest PAHs accumulating capability for total PAHs among three plants species. Oak leaves and pine needles show higher accumulating tendency for light and medium molecular weight PAHs, whereas moss presents stronger accumulating tendency for heavy molecular weight PAHs. Environmental factors (i.e., temperature, seasonality, and photolysis) also account for the process of PAHs transferred from air to plants. With the temperature climbing, the concentration of PAHs in the air will increase. Due to the meteorological conditions and the human activities changed with seasons, it was shown that the PAHs were greatly accumulated in leaf surface in winter than in summer. Photolysis was also able to influence the PAHs on leaf surface, which are significant to this process. In conclusion, oak, pine, and moss can be used to filter PAHs when considering urban landscaping. Besides combining the traditional analytical methods with in situ determination, there might be able to provide a novel method to further study the specific absorption mechanisms. The accumulation of PAHs in crop leaf surface related to the application of surfactants is also worth studying.
The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two evergreen tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V
cmax), maximum light-driven electron flux (J
max), day respiration rate (R
d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO2 assimilation versus intercellular CO2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V
cmax and J
max declined with the decrease in winter temperatures, whereas R
d at a set common temperature (25 °C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.
The competitive equilibrium between deciduous and evergreen plant species to a large extent depends on the intensity of the reduction in carbon gain undergone by evergreen leaves, associated with the leaf traits that confer resistance to stressful conditions during the unfavourable part of the year. This study explores the effects of winter harshness on the resistance traits of evergreen leaves. Leaf mass per unit area (LMA), leaf thickness and the concentrations of fibre, nitrogen (N), phosphorus (P), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in three evergreen and two deciduous species along a winter temperature gradient. In the evergreen species, LMA, thickness, and P and structural carbohydrate concentrations increased with the decrease in winter temperatures. Nitrogen and lignin concentrations did not show definite patterns in this regard. Chlorophyll, soluble proteins and Rubisco decreased with the increase in winter harshness. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates would be a requirement for the leaves to cope with low winter temperatures. The evergreen habit would be associated with higher costs at cooler sites, because the cold resistance traits imply additional maintenance costs and reduced N allocation to the photosynthetic machinery, associated with structural reinforcement at colder sites.
Pinus yunnanensis Franch. is an particular conifer tree species in Yunnan–Guizhou plateau in southwest China. The morphological and anatomical traits of needles are important to evaluate geographic variation and population dynamics of conifer species. Seedlings from seven populations of P. yunnanensis were analyzed, looking at 22 morphological and anatomical needle traits. The results showed that variations among and within populations were significantly different for all traits and the variance components within populations were generally higher than that among populations in the most tested needle traits. The proportions of three-needle fascicle were significantly different among populations. The traits related to needle size in both morphology and anatomy were positive with latitude and negative with annual temperature and precipitation. Ratio indices, including mesophyll area/vascular bundle area, mesophyll area/resin canals area, vascular bundle area/resin canals area and mesophyll area/(resin canals area and vascular bundle area), were negatively correlated with elevation and positively correlated with the annual mean temperature, showing some fitness feature for the populations. Needle traits were more significantly correlated with longitude than with other four environmental factors. Needle length was significantly correlated with almost all environmental factors. First four principal components accounted for 81.596 % of the variation with eigenvalues >1; the differences among populations were mainly dependent on needle width, stomatal density, section areas of vascular bundle, total resin canals, and mesophyll, as well as area ratio traits. Seven populations were divided into three categories by Euclidean distance. Variations in needle traits among the populations have shown systematic microevolution in terms of geographic impact on P. yunnanensis. This study would provide empirical data to characterize adaptation and genetic variation of P. yunnanensis, which would be helpful for management of genetic resources and reasonable utilization of them in future. © 2015 Northeast Forestry University and Springer-Verlag Berlin Heidelberg
The phenotypic differentiation of relic P. sylvestris in southern Europe and southwestern Asia was verified using thirty-two populations sampled from the Iberian Peninsula, Massif Central, Balkan Peninsula, Crimea and Anatolia. Twenty-one morphological and anatomical needle traits and 18 cone morphological characteristics were examined to describe the population diversity and differentiation. The needle characters were not correlated to those of cone. The differences between regions were significant based on 12 needle and 9 cone characteristics, suggesting spatial isolation. The differentiation between the Iberian and Anatolian populations was the highest, which indicates the isolation by distance. The high level of morphological differentiation was also found among Iberian populations, supporting the already known complex history of the species in that region. Populations within other regions were differentiated at lower levels; however, the West Anatolian populations differed morphologically from the eastern ones. The described pattern of morphological differentiation supports the idea of the long-lasting existence of P. sylvestris in the south-European and Anatolian mountain regions. To conserve this variation, seed transfer between regions in the forest economy should be restricted.
To evaluate the geographic variability of Pinus sylvestris populations seven morphological traits of needles of pines from IUFRO 1982 provenance trial have been analyzed. The studied populations originated from northern (>55°N in Russia, Sweden and Latvia), central (55-47°N in Poland, Germany, Belgium, France, Slovakia) and southern (<47°N in Hungary, Bosnia, Montenegro and Turkey) European ranges of Scots pine. The analyzed provenance trial experimental areas were located in Kórnik (western Poland) and in Supraśl (north-eastern Poland). The greatest variation was found in needle length and number of stomata rows on the flat and convex side of a needle, whereas number of stomata per 2 mm of needle length on flat and convex side of a needle was stable, with minor interpopulational variation. Biometrical analyses revealed a significant population × location interaction and a geographical pattern in interpopulational differentiation in both experimental sites, with the northern and southern European Scots pine groups of provenances differ-ing significantly from the group of central origin. The results obtained are compatible with previous results of studies on provenance variability of the Scots pine from IUFRO 1982. In the light of available data, the influ-ence of the Balkan glacial refugia of Pinus sylvestris on a present genetic diversity of this species in Europe and the reconstruction of Scots pine migration routes after the last glacial period are discussed.
Significance
How evergreen tree needle longevity varies from south to north in the boreal biome is poorly quantified and therefore ignored in vegetation and earth system models. This is problematic, because needle longevity translates directly into needle turnover rate and profoundly affects carbon cycling in both nature and computer models. Herein we present data for five widespread boreal conifers, including pines and spruces, from >125 sites along a 2,000-km gradient. For each species, individuals in colder, more northern environments had longer needle life span, highlighting its importance to evergreen ecological success. Incorporating biogeography of needle longevity into a global model improved predictions of forest productivity and carbon cycling and identified specific problems for models that ignore such variability.
We investigated the phenotypic variation of five morphological needle characters of Scots pine (Pinus sylvestris L.) in three populations. Two of the populations occurred in bogs and the third one formed a degraded fresh pine forest showing some features of a dry pine forest. The greatest variation was found in characters a (needle length), b and d, denoting the number of stomatal rows respectively on the convex and flat sides of the needle. Conversely, characters c and e (average number of stomata per 2 mm of needle length on the convex and the flat side of the needle) were stable, with little interindividual variation. The two bog populations and the dryland population exhibited different sets of character correlations. The interpopulation differentiational detected on the basis of morphological character expression was markedly influenced by both the different edaphic conditions, and the distinct genetic structure of the studied populations.
Early flowering plants are thought to have been woody species restricted to warm habitats. This lineage has since radiated into almost every climate, with manifold growth forms. As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing. To explore the evolution of traits underpinning the ability to persist in freezing conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to freezing). To model the evolution of species' traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully moved into freezing-prone environments by either possessing transport networks of small safe conduits and/or shutting down hydraulic function by dropping leaves during freezing. Herbaceous species largely avoided freezing periods by senescing cheaply constructed aboveground tissue. Growth habit has long been considered labile, but we find that growth habit was less labile than climate occupancy. Additionally, freezing environments were largely filled by lineages that had already become herbs or, when remaining woody, already had small conduits (that is, the trait evolved before the climate occupancy). By contrast, most deciduous woody lineages had an evolutionary shift to seasonally shedding their leaves only after exposure to freezing (that is, the climate occupancy evolved before the trait). For angiosperms to inhabit novel cold environments they had to gain new structural and functional trait solutions; our results suggest that many of these solutions were probably acquired before their foray into the cold.
Unlabelled:
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Premise of the study:
Plant species differ widely in the leaf biomass invested per unit area (LMA). LMA can be explained by variation in leaf thickness and/or density, both of which are influenced by anatomical tissue composition. The aim of this study is to quantify the anatomical characteristics that underlie variation in LMA in a range of woody species. •
Methods:
Twenty-six woody species, forming 13 species pairs with a deciduous and evergreen species from the same genus or family, were grown in a glasshouse. The youngest full-grown leaves were analyzed for LMA and morpho-anatomical characteristics at leaf, tissue, and cell level. •
Key results:
Considered over all species studied, leaf thickness and density were equally important to explain the variation in LMA, but the class difference between deciduous and evergreen species was mainly determined by thickness, whereas variation within each group was largely due to density. Evergreens had thicker leaves, predominantly caused by a larger volume of mesophyll and air spaces, whereas the higher leaf density within each group was due to a lower proportion of epidermis and air spaces, and overall smaller cells. •
Conclusions:
The anatomical basis for variation in LMA in woody species depends on the contrast made. Higher LMA in evergreens is mainly due to a greater leaf thickness, caused by a larger volume of mesophyll and air spaces. Within deciduous species and evergreens, higher LMA is caused by a higher density, due to higher volumetric fractions of mesophyll and lower fractions of air spaces and epidermis.
Patterns in the dominance of evergreen vs. deciduous plants have long interested ecologists, biogeographers, and global modellers. But previous models to account for these patterns have significant weaknesses. Bottom-up, mechanistic models - based on physiology, competition, and natural selection - have often been non-quantitative or restricted to a small range of habitats, and almost all have ignored belowground costs and whole-plant integration. Top-down, ecosystem-based models have succeeded in quantitatively reproducing several patterns, but rely partly on empirically derived constants and thresholds that lack a mechanistic explanation. It is generally recognized that seasonal drought can favor deciduous leaves, and that infertile soils can favor long-lived evergreen leaves. But no model has yet explained three great paradoxes, involving dominance by 1) evergreens in highly seasonal, boreal forests, 2) deciduous larch in many nutrient-poor peatlands, and 3) evergreen leaf-exchangers in nutrient-poor subtropical forests, even though they shed their leaves just as frequently as deciduous species. This paper outlines a generalized optimality model to account for these and other patterns in leaf longevity and phenology, based on maximizing whole-plant carbon gain or height growth, and building on recent advances in our understanding of the quantitative relationships of leaf photosynthesis, nitrogen content, and mass per unit area to leaf life-span. Only a whole-plant approach can explain evergreen dominance under realistic ecological conditions, or account for the boreal paradox, the larch paradox, the leaf-exchanger paradox, and expected shifts in shade tolerance associated with leaf phenology. Poor soils favor evergreens not merely by increasing the costs of nutrient acquisition, but also by depressing the maximum rate of photosynthesis and thus the seasonal contrast in photosynthetic return between leaves adapted to favorable vs. unfavorable conditions. The dominance of evergreens in western North America beyond the coastal zone of mild winters and winter rainfall appears related to the unusually long photosynthetic season for evergreen vs. deciduous plants there. Future models for optimal leaf phenology must incorporate differences between evergreen and deciduous plants in allocation to photosynthetic vs. non-photosynthetic tissue, rooting depth, stem allometry, xylem anatomy, and exposure to herbivores and leaching, and analyze how these differences interact with the photosynthetic rate, transpiration, and nutrient demands of leaves with different life-spans to affect rates of height growth in specific microsites.
Water in the xylem, the water transport system of plants, is vulnerable to freezing and cavitation, i.e. to phase change from liquid to ice or gaseous phase. The former is a threat in cold and the latter in dry environmental conditions. Here we show that a small xylem conduit diameter, which has previously been shown to be associated with lower cavitation pressure thus making a plant more drought resistant, is also associated with a decrease in the temperature required for ice nucleation in the xylem. Thus the susceptibility of freezing and cavitation are linked together in the xylem of plants. We explain this linkage by the regulation of the sizes of the nuclei catalysing freezing and drought cavitation. Our results offer better understanding of the similarities of adaption of plants to cold and drought stress, and offer new insights into the ability of plants to adapt to the changing environment.
Background: Broad-scale analysis of interspecific trait variation is a fundamental approach in comparative ecology to investigate general species-environment relationships, but inferences from environmental and phylogenetic signals are still controversially discussed. Aim: To analyse in a global study of the genus Pinus the interspecific variation of morphological traits with latitude as a surrogate of broad-scale environmental changes, and to compare latitudinal trait correlations with biogeographic, environmental, and phylogenetic signals in trait variation. Methods: Based on native range maps of 103 Pinus species, the latitudinal correlations of nine morphological traits, including needle characters, cone length and tree height were calculated. Principal component analysis was used to explore trait covariation. Variation partitioning was applied to disentangle environmental and phylogenetic signals in trait variation. Results: Strong latitudinal correlations were detected for traits, such as needle length:width ratio or needle longevity, with similar trends for different taxonomic species subsets and geographic regions. Strong latitudinal correlations were related to a decrease in the pure phylogenetic signal and to an increase in the phylogenetically structured environmental variation (PSEV), whereas the pure environmental signal was almost negligible. Conclusions: Besides a ranking of traits which differ in environmental and phylogenetic signals, our results showed a general relationship between increasing latitudinal trait correlation and an increase in PSEV which indicates phylogenetic niche conservatism. Thus, for the investigated morphological traits of the genus Pinus both environmental and phylogenetic signals are directly linked by PSEV to broad-scale spatial patterns in trait variation.
Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here we address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A(max)), leaf diffusive conductance (G(s)), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N-mass), SLA, G(s), and A(max) were positively related to one another and decreased with increasing lea
Ice storms are an important natural disturbance within forest ecosystems of the northeastern United States. Current models suggest that the frequency and severity of ice storms may increase in the coming decades in response to changes in climate. Because of the stochastic nature of ice storms and difficulties in predicting their occurrence, most past investigations of the ecological effects of ice storms across this region have been based on case studies following major storms. Here we report on a novel alternative approach where a glaze ice event was created experimentally under controlled conditions at the Hubbard Brook Experimental Forest, New Hampshire, USA. Water was sprayed over a northern hardwood forest canopy during February 2011, resulting in 7–12 mm radial ice thickness. Although this is below the minimum cutoff for ice storm warnings (13 mm of ice) issued by the US National Weather Service for the northeastern United States, this glaze ice treatment resulted in significant canopy damage, with 142 and 218 g C·m–2 of fine and coarse woody debris (respectively) deposited on the forest floor, a significant increase in leaf-on canopy openness, and increases in qualitative damage assessments following the treatment. This study demonstrates the feasibility of a relatively simple approach to simulating an ice storm and underscores the potency of this type of extreme event in shaping the future structure and function of northern hardwood forest ecosystems.
Within-species variation in needle traits is an important characteristic of conifers enabling trees to grow in different environments. We compared mean needle age (NA), shoot growth, and nutrient conservation in Scots pine (Pinus sylvestris L.) populations in different habitats and latitudes (peatlands and Vaccinium-type stands in Estonia (59°N) and Lapland (66°30′N)). In Vaccinium-type stands, trees with higher NA (mostly in Lapland) had lower shoot length increment and lower concentration of nitrogen and phosphorus in current-year needles than trees with low NA (mostly in Estonia). However, in peatlands, variation in NA (which was as high as in the Vaccinium-type stands) was weakly or insignificantly related to shoot growth and needle nutrient concentration. Within latitudes, pines with different shoot length increments and needle nutrient concentrations tend to have similar NAs. Resorption efficiency and concentration of nitrogen and phosphorus in senescent needles decreased with the initial concentrations of these nutrients in green needles. Our results demonstrate that slow growth and low needle nutrient concentration are not necessarily followed by higher NA and greater nutrient conservation in Scots pine. This is the opposite of the results often obtained in among-species comparisons or within species along latitudinal and altitudinal gradients.
Interspecific relationships among species mean leaf traits, performance and species resource/climate distributions help provide the foundation for a predictive, functionally based plant ecology. Intraspecific responses of leaf traits and performance to resource gradients and how these vary among species may be equally important but have received less attention. Here, we examine relationships between proxies of soil resource availability, leaf traits and growth (height at 25 years, SI(25)) for winter deciduous Larix decidua Mill. and evergreen Pinus resinosa Ait. trees distributed over soil resource gradients in the Great Lakes region of North America. We predicted that (i) leaf trait responses to soil resources within species will be similar to reported distributions of mean leaf traits over soil resource gradients among species; (ii) soil resource-related variation in leaf traits can help explain SI(25); and (iii) SI(25) will be greater for Larix than Pinus at higher soil resources and greater for Pinus than Larix at lower soil resources and this pattern will be associated with species differences in leaf trait responses to soil resources. Among the measured leaf traits (live N, Mg, Ca, K, P, and Mn, litter N, N resorption, carbon isotope discrimination, specific leaf area, lifespan), soil resources only impacted live and litter N for both species and K for Pinus. In turn, only the leaf traits responsive to soil resources affected SI(25) in the expected manner. Larix had greater SI(25) than Pinus across soil resource gradients and both species had similar growth and leaf trait sensitivities to resources. In summary: (i) several leaf traits reported to be associated with performance and edaphic distributions across species were, within species, unresponsive to nitrogen and water availability and unrelated to growth; (ii) leaf N showed high plasticity to soil resources and this plasticity was functionally relevant to growth over its entire range of response; (iii) large species-level differences in leaf traits between Larix and Pinus did not translate into different leaf trait and growth responses to soil resources.
1. Patterns of species co-existence and species diversity in plant communities remain an important research area despite over a century of intensive scrutiny. To provide mechanistic insight into the rules governing plant species co-existence and diversity, plant community ecologists are increasingly quantifying functional trait values for the species found in a wide range of communities.
2. Despite the promise of a quantitative functional trait approach to plant community ecology, we suggest that, along with examining trait variation across species, an assessment of trait variation within species should also be a key component of a trait-based approach to community ecology. Variability within and between individuals and populations is likely widespread due to plastic responses to highly localized abiotic and biotic interactions.
3. In this study, we quantify leaf trait variation within and across ten co-existing tree species in a dry tropical forest in Costa Rica to ask: (i) whether the majority of trait variation is located between species, within species, within individuals or within the leaves themselves; (ii) whether trait values collected using standardized methods correlate with those collected using unstandardized methods; and (iii) to what extent can we differentiate plant species on the basis of their traits?
4. We find that the majority of variation in traits was often explained by between species differences; however, between leaflet trait variation was very high for compound-leaved species. We also show that many species are difficult to reliably differentiate on the basis of functional traits even when sampling many individuals.
5. We suggest an ideal sample size of at least 10, and ideally 20, individuals be used when calculating mean trait values for individual species for entire communities, though even at large sample sizes, it remains unclear if community level trait values will allow comparisons on a larger geographic scale or if species traits are generally similar across scales. It will thus be critical to account for intraspecific variation by comparing species mean trait values across space in multiple microclimatic environments within local communities and along environmental gradients. Further, quantifying trait variability due to plasticity and inheritance will provide a better understanding of the underlying patterns and drivers of trait variation as well as the application of functional traits in outlining mechanisms of species co-existence.
We explored the relationship between leaf specific mass (LSM) and its two components, leaf density and thickness. These were assessed on the leaves of (a) the moderately sclerophyllous tree Arbutus menziesii distributed along a natural nutrient/moisture gradient in California, (b) eight sclerophyllous shrub species on four substrates in south-western Australia, and (c) seedlings of two morphologically contrasting Hakea species grown under varying soil nutrient, moisture and light regimes in a glasshouse experiment. Leaf area, mass, LSM, density and thickness varied greatly between leaves on the same plant, different species, and with different nutrient, moisture and light regimes. In some cases, variations in LSM were due to changes in leaf density in particular or thickness or both, while in others, density and thickness varied without a net effect on LSM. At lower nutrient or moisture availabilities or at higher light irradiances, leaves tended to be smaller, with higher LSM, density and thickness. Under increased stress, the thickness (diameter) of needle leaves decreased despite an increase in LSM. We concluded that, while LSM is a useful measure of sclerophylly, its separation into leaf density and thickness may be more appropriate as they often vary independently and appear to be more responsive to environmental gradients than LSM.
Foliar plasticity in response to ontogeny, location within the plant and environmental changes is widespread among long-lived
organisms. To quantify the phenotypic variation in needle morphology and anatomy in response to a climate gradient, we compared
contrasted populations of Pinus canariensis grown in five sites inside and outside the natural distribution area of the species. Most needle and growth traits were strongly
affected by site. In general, site xericity increased the relative area of the dermal and transfusion tissues and decreased
mesophyll and endodermis. Within each site, provenances from less productive locations tended to show longer needles, less
relative area of dermal tissues but higher relative area of mesophyll and transfusion tissue than provenances from fertile
origins. Although sclerophylly increased with aridity, no genetic differences were found for this trait thus apparently the
ontogenetic delay of some provenances in xeric environments was not related with the formation of tougher needles. Several
patterns of phenotypic response to different environments were shown. In general, all traits were plastic but the degree of
plasticity was higher in traits related with growth than foliar traits. These results, combined with formerly published research,
suggest that highly plastic populations rather than narrowly specialized ones have been selected in this species to cope with
the complex interaction of environmental factors in its habitat.
KeywordsPhenotypic plasticity-Needle anatomy-Needle morphology-Drought period-
Pinus canariensis
The winter desiccation of needles is thought to limit tree growth and survival within alpine timberline ecotones of the southern Rocky Mountains, USA. To better understand the factors contributing to this desiccation damage, the extent to which stem water was available to needles of Picea engelmannii undergoing desiccation at timberline near Monarch Pass, Colorado, was monitored throughout the winter. Severed shoots experienced significantly greater desiccation than did intact shoots, indicating the availability of stem water to needles despite presumably frozen soil, roots, and stems. A model of water relations during winter predicted more extreme desiccation of severed shoots than observed. This suggests that one or more of the common assumptions concerning the winter water relations of timberline trees is in error. The influence of cold, dry conditions on the cuticular conductance of Picea engelmannii needles is not known and therefore not accounted for in current models of winter water relations. The assumption that cuticular conductance is not influenced by temperature or humidity is a likely source of error in such models.
Aim
Scots pine is one of the dominant tree species in forest ecosystems of the temperate and boreal zones in Eurasia. Since the Tertiary, it has persisted also in the Mediterranean region, forming relict populations. In this study, we investigate range-wide genetic diversity of Scots pine, aiming to provide comprehensive information on the phylogeography and genetic resources of the species.
Location
Europe and Asia.
Methods
Thirteen paternally inherited chloroplast microsatellite (cpSSR) loci were used to investigate the genetic structure of 62 populations from Fennoscandia and 30 populations from the Mediterranean. We also surveyed variability of two maternally inherited mitochondrial DNA (mtDNA) regions and additionally included literature data from 156 populations (248 populations in total).
Results
Scots pine retains an overall high genetic diversity in the chloroplast genome but, unexpectedly, the historically younger populations from Fennoscandia showed statistically higher mean intrapopulation diversity than the Mediterranean stands (0.807 and 0.750, respectively). The latter also contained a lower number of private cpSSR haplotypes. Population differentiation with respect to mtDNA was higher (GST = 0.628) than at cpSSR (GST = 0.015) indicating an efficient pollen-mediated gene flow among refugial populations of the species. One novel haplotype mtDNA was found, increasing the number of known mitotypes for the species from 4 to 5. The geographic distribution of mitotypes was structured into four groups corresponding to the main refugial areas of the species.
Main conclusions
Genetic impoverishment of the Mediterranean populations may enhance their vulnerability to future environmental changes. The spatial distribution of two mitotypes in Fennoscandia, featuring predominance of mitotype a in Norway and Sweden and mitotype b in Finland, gives strong support for dual colonization of that region from south-eastern (Finland) and south-western (Sweden) directions. These results thus provide new insights into both Holocene expansion of Scots pine and the present distribution of species' genetic resources.
Leaf dry mass per unit leaf area (LMA) is a central trait in ecology, but its anatomical and compositional basis has been unclear. An explicit mathematical and physical framework for quantifying the cell and tissue determinants of LMA will enable tests of their influence on species, communities and ecosystems. We present an approach to explaining LMA from the numbers, dimensions and mass densities of leaf cells and tissues, which provided unprecedented explanatory power for 11 broadleaved woody angiosperm species diverse in LMA (33-262 g m(-2) ; R(2) = 0.94; P < 0.001). Across these diverse species, and in a larger comparison of evergreen vs. deciduous angiosperms, high LMA resulted principally from larger cell sizes, greater major vein allocation, greater numbers of mesophyll cell layers and higher cell mass densities. This explicit approach enables relating leaf anatomy and composition to a wide range of processes in physiological, evolutionary, community and macroecology.
Aims
Contrasting leaf types with different leaf life spans represent different adaptive strategies in plants. Previous studies explained the adaptive advantages of different strategies on the basis of environmental climatic limits, but could not account for the observed co‐dominance of multiple plant functional types (PFTs) in many regions. Here we used a process‐based model to explore whether observed inter‐ and intra‐PFT variation in plant traits can explain global biogeographical variation in the dominance and co‐dominance of major forest types.
Location
World‐wide.
Methods
We identified four important plant traits: leaf N concentration, leaf life span, fraction of net primary production (NPP) allocated to leaves and plant basal respiration rate. We incorporated means and variances of these plant traits from trait databases into the Community Atmosphere–Biosphere–Land Exchange model. We then predicted the dominant PFT or PFT mixture for global forested grid cells, using NPP as a proxy for growth rate, and considering three PFTs: evergreen needleleaf forests (ENF), evergreen broadleaf forests (EBF) and deciduous broadleaf forests (DBF). We compared results with: (1) those from simulations that did not account for trait variance; (2) results from an empirical model based purely on mean annual temperature; and (3) data from remotely sensed observations.
Results
Our estimates of the fractions of land area covered by major forest types were consistent with observation; i.e. ENFs dominate in boreal regions, EBFs dominate in tropical regions and DBFs are distributed widely across a broad range of environmental conditions. We also showed that co‐dominance of different forest PFTs cannot be reproduced without considering variation in plant traits.
Main conclusions
Global trait data are useful for representing underlying plant strategies and functional diversity. Variation in key plant traits explains significant fractions of global biogeographical variation of three major forest types. Future developments in dynamic global vegetation modelling will benefit from the inclusion of plant trait variation.
Together with carbon, oxygen and hydrogen, nitrogen is one of the four most common elements in living cells and an essential constituent of proteins and nucleic acids, the two groups of substances which can be said to support life. Yet the element is not particularly common on earth, with the exception of the atmosphere, which contains almost 80% nitrogen. The estimated 11000 to 14000 teragrams (1012) nitrogen in living biomass (mainly terrestrial plants) is equivalent to about three parts per million of the atmospheric nitrogen (Table 1.1). Other important nitrogen pools are: soil organic matter, rocks (in fact the largest single pool), sediments, coal deposits, organic matter in ocean water, and nitrate in ocean water. The next most common gaseous form of nitrogen in the atmosphere after molecular nitrogen is dinitrogen oxide.
The degree of herbivory and the effectiveness of defenses varies widely among plant species. Resource availability in the environment is proposed as the major determinant of both the amount and type of plant defense. When resources are limited, plants with inherently slow growth are favored over those with fast growth rates; slow rates in turn favor large investments in antiherbivore defenses. Leaf lifetime, also determined by resource availability, affects the relative advantages of defenses with different turnover rates. Relative limitation of different resources also constrains the types of defenses. The proposals are compared with other theories on the evolution of plant defenses.
Freezing is a major environmental stress during an annual cycle of overwintering, temperate-zone perennials. The timing and extent of seasonal cold acclimation (development of freezing tolerance in the fall) and deacclimation (loss of acquired freezing tolerance in response to warm temperatures) are of critical importance for winter survival, particularly in view of the climate change, i.e., unpredictable extreme weather occurrences. For example, plants may acclimate inadequately if exposed to a milder fall climate and may be damaged by sudden frosts. Alternatively, they may deacclimate prematurely as a result of unseasonable, midwinter warm spells and be injured by the cold that follows. Efficient cold acclimation ability, high deacclimation resistance, and efficient reacclimation capacity are, therefore, important components of winter survival in overwintering perennials. These components should be evaluated separately for a successful breeding program focused on improving winter-hardiness. Another layer of complexity that should be carefully considered is that endodormant status (shallow versus deep) of the reproductive/vegetative apices can significantly impact these components of winter-hardiness. Winter survival, especially by woody evergreens, requires tolerance of light stress, which can result in photo-oxidative damage at cold temperatures when biochemistry of photosynthesis is somewhat compromised but light harvesting is unaffected. Accumulation of Elips (early light-induced proteins) in overwintering evergreens during winter represents a relatively novel strategy to cope with such light stress, and investigations on the precise cellular mechanism and genetic control of this strategy deserve research in the future. Investigations into the mechanisms for cold acclimation use laboratory-based, artificial acclimation protocols that often do not closely approximate conditions that plants are typically exposed to in nature. To draw meaningful conclusions about the biology of cold acclimation and ultimately improve freeze resistance under field conditions, one should also include in cold acclimation regimens parameters such as exposure to subfreezing temperatures and realistic diurnal temperature fluctuations and light levels to simulate natural conditions. One of the main objectives of this article is to highlight two areas of research that we believe are important in the context of plant cold-hardiness but, so far, have not received much attention. These are: 1) to understand the biology of deacclimation resistance and reacclimation capacity, two important components of freeze-stress resistance (winter-hardiness) in woody perennials; and 2) to investigate the cellular basis for various strategies used by broad-leaved evergreens for photoprotection during winter. Our emphasis, in this context, is on a family of proteins, called Elips. The second objective of this article is to draw attention of the cold-hardiness research community to the importance of using realistic cold acclimation protocols in controlled environments that will approximate natural/field conditions to be better able to draw meaningful conclusions about the biology of cold acclimation and ultimately improve freeze resistance. Results from our work with Rhododendron (deciduous azaleas and broad-leaved evergreens), blueberry, and that of other researchers are discussed to support these objectives.
In 1966-67 in the eastern part of Hokkaido, where severe cold weather and a dry state prevailed throughout the winter, most young conifers, especially those wintering on the southern slopes, were seriously damaged. Minimum temperature was about @o30@?C, and soil temperature at 10-cm depth even on the southern slopes remained below zero for 3.5 months. Soil was frozen down to about 40 cm. Temperatures of stems and leaves of young conifers wintering on the southern and northern slopes rose to about 17@? and 9@?C, respectively, in midday and remained unfrozen for about 6 and 2 hr, respectively, in the daytime. Under these conditions, the conifers wintering on the southern slopes were intensely dehydrated towards the end of February. In most damaged trees, browning was observed on the stem bark. Trees in which desiccation damage was artificially induced exhibited nearly the same browning as that observed in trees suffering damage under natural conditions. Stems and leaves of young Sakhalin fir and Ezo spruce could stand freezing in winter below @o50C, and white pine and American arborvitate which sustained damage seriously under natural conditions also survived freezing below @o120@?C. Young conifers wintering in frozen soil were damaged by dehydration resulting from a combination of freezing of soil and exposure to sunshine.
The evolutionary response of plants to herbivory is constrained by the availability of resources in the environment. Woody plants adapted to low-resource environments have intrinsically slow growth rates that limit their capacity to grow rapidly beyond the reach of most browsing mammals. Their low capacity to acquire resources limits their potential for compensatory growth which would otherwise enable them to replace tissue destroyed by browsing. Plants adapted to low-resource environments have responded to browsing by evolving strong constitutive defenses with relatively low ontogenetic plasticity. Because nutrients are often more limiting than light in boreal forests, slowly growing boreal forest trees utilize carbon-based rather than nitrogen-based defenses. More rapidly growing shade-intolerant trees that are adapted to growth in high-resource environments are selected for competitive ability and can grow rapidly beyond the range of most browsing mammals. Moreover, these plants have the carbon and nutrient reserves necessary to replace tissue lost to browsing through compensatory growth. However, because browsing of juvenile plants reduces vertical growth and thus competitive ability, these plants are selected for resistance to browsing during the juvenile growth phase. Consequently, early successional boreal forest trees have responded to browsing by evolving strong defenses during juvenility only. Because severe pruning causes woody plants to revert to a juvenile form, resistance of woody plants to hares increases after severe hare browsing as occurs during hare population outbreaks. This increase in browsing resistance may play a significant role in boreal forest plant-hare interactions. Unlike woody plants, graminoids retain large reserves of carbon and nutrients below ground in both low-resource and high-resource environments and can respond to severe grazing through compensatory growth. These fundamental differences between the response of woody plants and graminoids to vertebrate herbivory suggest that the dynamics of browsing systems and grazing systems are qualitatively different. /// Эволюционная реакция растений на выедание фитофагами органичивается дос-тупностью ресурсов в природной среде. Древесые растения, адаптированные к местообитаниям с низкнм количеством ресурсов, имеют эндогенные низкие темпы роста, что лимитирует их способность к быстрому росту после повреж-дения мпекопитающими, обьедающими побеги. Их низкая способность к утили-зации ресурсов ограничивает их потенцию к компенсаторному росту, возме-щающему ткани, поврежденные при обьедании побегов. Растения, адаптирован-ные к местообитаниям с низким запасом ресурсов, реагируют на повреждения развитием сильных конструктивных защитных механизмов с относительно низ-кой онтогенетической пластичностью. Так как элементы питания часто более ограничены, чем освещение в бореальных лесах, медленно растущие деревья бореальных лесов используют защитные механизмы, основанные чаще на угле-родных, нежели азотных соединениях. У быстрее растущих деревьев, чувстви-тельных к затенеию, которые адаптированы к росту в более обеспеченных ре-сурсами местообитаниях, отбор был направлен на конкурентоспособность, они могут быстро расти после повреждений большинства млекопитакщих, обьедаю-щих побеги. Голее того, эти растения имеют резервы углерда и азота, не-обходимые для замещения обьеденных тканей в процессе компесаторного роста. Однако, так как обьедание молодых растений снижает их вертикальный рост и таким образом конкурентоспособность у этих растений отбор направлен на устойчивость к обьеданию в течение ювенильной фазы роста. Следовательно, деревья бореальных лесов ранний сукцессионной реагируют на обьеда-ние рзвитием сильных защитных механизмов лишь в незрелом состоянии. Так как сильное обьедание возращает древесные растения к ювенильной форме, у-стойчивость древесных растений к повреждениям зайцев поьшается после сильного обьедания зайцами, как это наблюдалось в периоды вспышек числен-ности их популяций. Это повышение устойчивости к обьеданию может играть существенную роль в отношениях растение-заяц, в бореальных лесах. В отли-чие от древесных растений, злаковые сохраняют резервы углерода и других элементов в подземных частях в местообитаниях с низкой и высокой обеспе-ченностью ресурсами и могут реагировать на сильный выпас компенсаторным ростом. Эти функциональные различия между реакцией древесных растений и злаков на выедание млекопитаюшими показывает, что динамика систем обгла-дывания и пастьбы качественно различны.
The leaf economics spectrum is a general concept describing coordinated variation in foliage structural, chemical and physiological traits across resource gradients. Yet, within this concept, the role of within-species variation, including ecotypic and plastic variation components, has been largely neglected. This study hypothesized that there is a within-species economics spectrum within the general spectrum in the evergreen sclerophyll Quercus ilex which dominates low resource ecosystems over an exceptionally wide range. An extensive database of foliage traits covering the full species range was constructed, and improved filtering algorithms were developed. Standardized data filtering was deemed absolutely essential as additional variation sources can result in trait variation of 10–300%, blurring the broad relationships. Strong trait variation, c. two-fold for most traits to up to almost an order of magnitude, was uncovered. Although the Q. ilex spectrum is part of the general spectrum, within-species trait and climatic relationships in this species partly differed from the overall spectrum. Contrary to world-wide trends, Q. ilex does not necessarily have a low nitrogen content per mass and can increase photosynthetic capacity with increasing foliage robustness. This study argues that the within-species economics spectrum needs to be considered in regional- to biome-level analyses.
The leaf economics spectrum (LES) provides a useful framework for examining species strategies as shaped by their evolutionary history. However, that spectrum, as originally described, involved only two key resources (carbon and nutrients) and one of three economically important plant organs. Herein, I evaluate whether the economics spectrum idea can be broadly extended to water – the third key resource –stems, roots and entire plants and to individual, community and ecosystem scales. My overarching hypothesis is that strong selection along trait trade‐off axes, in tandem with biophysical constraints, results in convergence for any taxon on a uniformly fast, medium or slow strategy (i.e. rates of resource acquisition and processing) for all organs and all resources.
Evidence for economic trait spectra exists for stems and roots as well as leaves, and for traits related to water as well as carbon and nutrients. These apply generally within and across scales (within and across communities, climate zones, biomes and lineages).
There are linkages across organs and coupling among resources, resulting in an integrated whole‐plant economics spectrum. Species capable of moving water rapidly have low tissue density, short tissue life span and high rates of resource acquisition and flux at organ and individual scales. The reverse is true for species with the slow strategy. Different traits may be important in different conditions, but as being fast in one respect generally requires being fast in others, being fast or slow is a general feature of species.
Economic traits influence performance and fitness consistent with trait‐based theory about underlying adaptive mechanisms. Traits help explain differences in growth and survival across resource gradients and thus help explain the distribution of species and the assembly of communities across light, water and nutrient gradients. Traits scale up – fast traits are associated with faster rates of ecosystem processes such as decomposition or primary productivity, and slow traits with slow process rates.
Synthesis . Traits matter. A single ‘fast–slow’ plant economics spectrum that integrates across leaves, stems and roots is a key feature of the plant universe and helps to explain individual ecological strategies, community assembly processes and the functioning of ecosystems.
Differences in terms of depth of dormancy have been revealed in the provenace trial of Scots pine based on an analysis of parameters of the zero fluorescence level, as well as the content of chlorophylls and abscisic acid, which corresponds to the results of studying the pine-needle morphological traits and phenological observations. Trees of the southern climatype different in terms of needle morphological traits and the length of phenological stages are characterized by a deeper dormancy than those of the northern climatype. It is assumed that, due to climate change, northern climatypes would be more vulnerable during winter-spring thaws, which were not typical of these regions in former times.
Although intraspecific trait variability is an important component of species ecological plasticity and niche breadth, its implications for community and functional ecology have not been thoroughly explored. We characterized the intraspecific functional trait variability of Scots pine (Pinus sylvestris) in Catalonia (NE Spain) in order to (1) compare it to the interspecific trait variability of trees in the same region, (2) explore the relationships among functional traits and the relationships between them and stand and climatic variables, and (3) study the role of functional trait variability as a determinant of radial growth. We considered five traits: wood density (WD), maximum tree height (H max), leaf nitrogen content (Nmass), specific leaf area (SLA), and leaf biomass-to-sapwood area ratio (B L:A S). A unique dataset was obtained from the Ecological and Forest Inventory of Catalonia (IEFC), including data from 406 plots. Intraspecific trait variation was substantial for all traits, with coefficients of variation ranging between 8 % for WD and 24 % for B L:A S. In some cases, correlations among functional traits differed from those reported across species (e.g., H max and WD were positively related, whereas SLA and Nmass were uncorrelated). Overall, our model accounted for 47 % of the spatial variability in Scots pine radial growth. Our study emphasizes the hierarchy of factors that determine intraspecific variations in functional traits in Scots pine and their strong association with spatial variability in radial growth. We claim that intraspecific trait variation is an important determinant of responses of plants to changes in climate and other environmental factors, and should be included in predictive models of vegetation dynamics.
Summary
1. The mechanical resistance of leaves has key ecological implications but its basis has not
been well understood, particularly at the tissue scale. We tested the hypotheses that leaf
mechanical resistance should be a function of tissue density, increasing from the lamina to the
midrib, and higher in drought-tolerant than drought-avoiding species.
2. In a common garden study, we quantified nine leaf biomechanical traits, including measurements
of material and structural resistance, and in addition 17 morphological traits, at the tissue
and whole-leaf scales, for 21 species from three semi-arid communities of California, USA.
3. The mechanical properties of leaves depended strongly on tissue density. Material resistance
was significantly greater in the midrib than in the leaf lamina, and tissue resistances were significantly
correlated among tissues, lower in deciduous coastal sage species and higher in evergreen
drought-tolerant chaparral species. The proportion of the biomass invested in the midrib
was lower in species bearing midribs and laminas of high material resistance.
4. Our results support the hypothesis of a hierarchical partitioning of leaf mechanical resistance
among leaf tissues reflecting the investment of dry mass. Also, our data indicated a
mechanical compensation in leaf design, where leaves with high material resistance and density
deploy a relatively minor proportion of support tissue in the midrib. Finally, our results establish
a quantitative basis for differences among communities in leaf biomechanics. Our results
supported the classical characterization of the mediterranean-climate flora of California
according to the dramatic increase in the mean leaf mechanical resistance from species of
coastal sage to chaparral, with diverse leaf types in the Mojave Desert species.
Key-words: allometry, chaparral, coastal sage, Mojave Desert vegetation, plant economics,
sclerophylly, stiffness, strength
Freeze avoidance has evolved in plants in response to selection pressures brought about by exposure to freezing temperatures. It is a multifaceted adaptive mechanism with many attributes. Despite the prevalence of freeze avoidance as an adaptive mechanism little research has been devoted in recent times to understanding the underlying mechanisms and regulation of freeze avoidance. Therefore, there is no shortage of questions that need to be addressed. Inherent in understanding how plants respond to freezing temperatures is the need to know the properties of water at different temperatures and how the interaction of water with biological substances affects these properties. This review provides an overview of the subject of biological ice nucleation and propagation and how various aspects of plant structure and composition can affect the freezing process. Deep supercooling of plant tissues represents the most extreme example of freeze avoidance. The potential role of anti-nucleating substances in defining the ability to deep supercool is also discussed. The importance of studying intact plants in their natural environments is emphasized. Although, this adds a high degree of complexity to investigations, it is in this context that adaptive mechanisms have evolved and play a role in the biology and survival of plants.
The winter desiccation of needles is thought to limit tree growth and survival within alpine timberline ecotones of the southern Rocky Mountains, USA. To better understand the factors contributing to this desiccation damage, the extent to which stem water was available to needles of Picea engelmannii undergoing desiccation at timberline near Monarch Pass, Colorado, was monitored throughout the winter Severed shoots experienced significantly greater desiccation than did intact shoots, indicating the availability of stem water to needles despite presumably frozen soil, roots, and stems. A model of water relations during winter predicted more extreme desiccation of severed shoots than observed. This suggests that one or more of the common assumptions concerning the winter water relations of timberline trees is in error. The influence of cold, dry conditions on the cuticular conductance of Picea engelmannii needles is not known and therefore not accounted for in current models of winter water relations. The assumption that cuticular conductance is not influenced by temperature or humidity is a likely source of error in such models.
Conifers are among the most frost tolerant tree species. Cryo-scanning electron microscopy (cryo-SEM) was used to visualise ice formation in pine needles to better understand how conifer leaves manage extracellular ice. Acclimated and unacclimated needles of Pinus radiata (D.Don) were subjected to freezing treatments (at a rate of 2°Ch-1), tested for electrolyte leakage and sampled for cryo-SEM analysis. Half maximal electrolyte leakage occurred at -4 and -12°C for unacclimated and acclimated needles, respectively. Ice nucleation occurred at similar temperatures (-3°C) in both acclimated and unacclimated pine needles, indicating that frost tolerance did not increase supercooling. During freezing and thawing, the tissues outside and inside the endodermis shrank and swelled independently, with little or no transfer of water between the two regions. During freezing, mesophyll cells shrank, exhibiting cytorrhysis, and extracellular ice accumulated in gas spaces of the mesophyll tissue. Mesophyll cells from acclimated needles recovered their structure after thawing, and unacclimated mesophyll showed significant damage. In the vascular cylinder, ice accumulated in transfusion tracheids which expanded to occupy areas made vacant by shrinkage of transfusion parenchyma, Strasburger cells and the endodermis. This behaviour was reversible in acclimated tissue, and may play an important role in the management of ice during freeze/thaw events.
The relationships between freezing temperature (or supercooling) and length, weight, and water content of Pinus and Cedrus needles were investigated. Freezing temperature was an increasing function of each of these three variables. When Pinus needles were cut proximally to uniform length (50 mm), supercooling was unaffected by either weight or water content. Thus, ice nucleation temperature was an increasing function of the length of needles, or, more precisely, of the length of the stele, or, still more precisely, of the number of water-conducting capillary units contributing to that length, but ultimately of the number and quality of favorable nucleation sites contained therein. It is suggested that nucleation takes place at sites associated with the cell walls and not on nucleators suspended in the water.
Leaf dry mass per unit area (LMA) is a product of leaf thickness (T) and of density (D). Greater T is associated with greater foliar photosynthetic rates per unit area because of accumulation of photosynthetic compounds; greater D results in decreased foliage photosynthetic potentials per unit dry mass because of lower concentrations of assimilative leaf compounds and decreases in intercellular transfer conductance to CO2. To understand the considerable variation in T and D at the global scale, literature data were analyzed for 558 broad-leaved and 39 needle-leaved shrubs and trees from 182 geographical locations distributed over all major earth biomes with woody vegetation. Site climatic data were interpolated from long-term world climatologies (monthly precipitation, surface temperature) or modeled using the Canadian Climate Center Model (monthly global solar radiation). Influences of total annual precipitation (W-T), precipitation of the driest month (W-min), monthly mean precipitation of the three driest months in the year (W-3min), highest monthly precipitation (W-max), precipitation index ([W-max - W-min]/W-T), mean, minimum, and maximum annual monthly temperatures, and daily annual mean global solar radiation (R) on LMA, D, and T were tested by simple and multiple linear and log-linear regression analyses. In broad-leaved species, LMA and T increased with increasing R and mean temperature and scaled weakly and negatively with precipitation variables, but D was negatively related only to precipitation. Similar relationships were also detected in needle-leaved species, except that, in multiple regression analysis, precipitation did not significantly influence leaf thickness, and R was positively related to D. Given that increases in LMA and T are compatible with enhanced photosynthetic capacities per unit leaf area, but also with greater costs for construction of unit surface area, positive effects of solar irradiance and surface temperature on these variables are indicative of shorter leaf pay-back times in conditions of higher irradiance and temperature allowing construction of leaves with higher photosynthetic potential. To gain insight into the scaling of leaf density with site aridity, correlations of D with the leaf elastic modulus close to full turgor (epsilon) and with the leaf osmotic potentials (pi) at full and zero turgor were analyzed. Both low pi, which is compatible with low leaf water potential, and high epsilon, which permits large adjustment of leaf water potential with small changes in leaf water content, may facilitate water uptake from drying soil. Leaf elastic modulus was independent of T and was weakly related to LMA; but there were close positive associations of epsilon with D and leaf dry to fresh mass ratio, which is an estimate of apoplastic leaf fraction. Consequently, changes in D bring about modifications in leaf elasticity and allow tolerance of water limitations. Across all the data, epsilon and the estimates of pi were negatively related. However, given that pi varied only fourfold, but epsilon 10-fold, I conclude that osmotic adjustment of leaf water relations is inherently limited, and that elastic adjustment resulting from changes in leaf structure may be a more important and general way for plants to adapt to water-limited environments.
Shoot and needle growth of 20-year-old Pinus sylvestris trees was studied in relation to the temperature of the current and previous seasons at three localities in Northern Fennoscandia over a 10-year period. Leader length and the number of needle fascicles per leader had highly significant positive correlation coefficients with the mean June-August temperature of the previous season. A low number of needle fascicles per leader was associated with a high frequency of fascicles with three needles. Needle length showed a significant positive correlation with the mean temperature of the current growing season, particularly June-August temperature. Use of heat sums or respiration equivalents instead of mean temperatures did not significantly improve correlation coefficients. A highly significant positive correlation was also found between needle length and next year's leader growth. Forest Sci. 27:423-430.
Needle mass, length, and nitrogen concentration, and their relation to site index were studied for lodgepole pine (Pinus contorta Dougl.) and Scots pine (Pinus sylvestris L.). Needles were collected at 53 locations throughout Sweden where the two species, of the same age, were growing on adjacent, comparable sites. Sampling was done throughout the growing season, with a pause during the period of most active growth. Needles of lodgepole pine had a higher mass, were longer, and had a lower nitrogen concentration than those of Scots pine. Site index was positively correlated to needle length and weight for both species, and to nitrogen concentration for lodgepole pine. For the characteristics studied, the relative differences between needles of the two species decreased with increasing site index.
1. Small leaves of species endemic to Mediterranean-type climate areas have been associated with both low rainfall and nutrient availability, but the physiological reasons for this association remain unknown.
2. We postulated that small leaves have thin boundary layers that facilitate transpiration in winter and sensible heat loss in summer. High transpiration rates when water is available may facilitate nutrient acquisition in winter, whereas efficient sensible heat loss reduces the requirement for transpirational leaf cooling in summer.
3. The consequences of varying leaf sizes for water and heat loss in Cape Proteaceae were examined at two scales. At the leaf level, gas exchange and thermoregulatory capacities of 15 Proteaceae species with varying leaf size were assessed under controlled conditions using phylogenetically independent contrasts. At an environmental level, leaf attributes of Proteaceae occurring in the winter-rainfall area of the Cape Floristic Region were correlated with climatic environments derived from distribution data for each species.
4. Leaf temperature was positively correlated with leaf size when wind speed was negligible. However, transpiration decreased significantly with increasing leaf size when measured on individual leaves, detached branches and when expressed on a per stoma basis.
5. From multiple stepwise regression analysis of climatic variables obtained from distribution data, leaf size was negatively correlated with A-Pan evaporation, mean annual temperatures and water stress in January. We conclude that leaf size is conservative for survival over relatively rare periods of hot dry conditions with low wind speeds.
6. Narrow leaves enable plants to shed heat through sensible heat loss during summer droughts, without the need for transpirational cooling. Additionally, small leaf dimensions confer a capacity for high transpiration when evaporative demand is low and water is abundant (i.e. winter). This may be a particularly important strategy for driving nutrient mass-flow to the roots of plants that take up most of their nutrients in the wet winter/spring months from nutrient-poor soils.
The Digital Climatic Atlas and the Ecological and the Forestry Inventory of Catalonia (NE Spain) were analysed to study the climate effect on leaf mass per area (LMA) and leaf area index (LAI) on Quercus ilex L., one of the most widely spread tree species in the Mediterranean region. 195 sites in this region of 31,895km2 were considered. The relationship between climatic variables (total annual rainfall, mean annual temperature, mean minimum winter temperatures, and mean annual solar radiation) and LMA and LAI were analysed by simple and multiple regressions. LMA was higher in the drier sites and specially in the colder sites. There was also a significant correlation between solar radiation and LMA. On the contrary, LAI values, which were negatively correlated with LMA values, were lower in drier and colder sites, and were not significantly affected by solar radiation. The results highlight that high LMA values do not seem to be a specific protection to dry conditions but to a wide range of environmental stress factors, including low temperatures.
The relationships of foliage assimilation capacity per unit area (PPmax) with leaf dry mass per unit area (LMA) and nitrogen content per unit area (NP) differ between species and within species grown in different habitats. To gain a more mechanistic insight into the dependencies of PPmax on LMA and NP, this literature study based on 597 species from a wide range of earth biomes with woody vegetation examines the relations between leaf photosynthetic capacity and the components of LMA (leaf density (D, dry mass per volume) and thickness (T)), and also the correlations of D and T with leaf nitrogen content and fractional leaf volumes in different tissues. Across all species, PPmax varied 12-fold and photosynthetic capacity per unit dry mass (Pmmax) 16-fold, NP 12-fold, and nitrogen per unit dry mass (Nm) 13-fold, LMA 46-fold, D 13-fold, and T 35-fold, indicating that foliar morphology was more plastic than foliar chemistry and assimilation rates. Although there were strong positive correlations between PPmax and NP, and between Pmmax and Nm, leaf structure was a more important determinant of leaf assimilation capacities. PPmax increased with increasing LMA and T, but was independent of D. By contrast, Pmmax scaled negatively with LMA because of a negative correlation between Pmmax and D, and was poorly related to T. Analysis of leaf nitrogen and tissue composition data indicated that the negative relationship between D and Pmmax resulted from negative correlations between D and Nm, D and volumetric fraction of leaf internal air space, and D and symplasmic leaf fraction. Thus, increases in leaf density bring about (1) decreases in assimilative leaf compounds, and (2) extensive modifications in leaf anatomy that may result in increases in intercellular transfer resistance to CO2. Collectively, (1) and (2) lead to decreased Pmmax, and also modify PPmax versus LMA relationships.
Winter desiccation-induced foliage loss at high-elevation locations is an important determinant of positive carbon balance for trees and thus influences the location of the alpine treeline ecotone. In this study, data are presented that describe the amount of winter desiccation incurred by krummholz growth forms of subalpine fir (Abies lasiocarpa (Hook) Nutt.) at treeline locations in Glacier National Park, Montana, USA, for the winter of 1998/1999. An average 8.68% of the krummholz canopy was lost due to desiccation.
Winter desiccation is not predictable based on any single environmental variable. When outliers are removed, winter desiccation shows a strong correlation with elevation (r= 0.97). Patch level winter desiccation amounts are, however, highly predictable from elevation, slope, aspect and topographic context when considered together. In general, injury increases with elevation and on more southwesterly facing hillslopes. High slopes and sheltered locations decrease winter desiccation.
Within patches, most winter desiccation is located at the windward edge of the patch. This trend may be modified by the presence of leaders above the mean canopy surface of the krummholz patch, or by local microtopographic features such as dead branches or the proximity of large rocks.
The winter of 1998/1999 was a high winter desiccation year compared to the two previous winters. The winter of 1998/1999 had high snowfall, and meltout did not occur until later than the previous two winters. The extended period of snow cover is hypothesized to be one of the causes of the increased winter desiccation for the 1998/1999 winter.
Evergreen boreal plant species express high variability in their leaf traits. It remains controversial whether this within-species
variability is constrained to the same leaf trait relationships as has been observed across species. We sampled leaves of
three boreal evergreen woody species along a latitudinal gradient (from 57º56′N to 69º55′N). Leaf longevity (LL) of Pinussylvestris L. and Vacciniumvitis-idaea L. correlated negatively with mean annual air temperature (MAT), whereas the LL of Ledumpalustre L. was not affected by MAT. V.vitis-idaea and L.palustre had a negative relationship between leaf mass per area (LMA) and MAT. In P.sylvestris, the LMA–MAT relationship was positive. A negative correlation between LL and LMA was significant only for P.sylvestris. Leaf nitrogen concentration was positively related to leaf phosphorus concentration in all three species. Leaf potassium
concentration was related to nitrogen concentration only in L.palustre, and to phosphorus concentration in P.sylvestris and L.palustre. Our results demonstrate that although within the studied species the variation in some of the leaf traits may have the same
degree as interspecific variation, there is no such intercorrelation of leaf traits within the studied species as has been
observed across species.
KeywordsBoreal forest-Evergreen plants-Leaf traits-Nutrients-Temperature
Morphophysiological and anatomical characters of needles that are used for characterizing infraspecific taxa have been studied Morphophysiological and anatomical characters of needles that are used for characterizing infraspecific taxa have been studied
in Scotch pine geographic cultures established in the forest-steppe zone of Siberia. Variation in these characters has been in Scotch pine geographic cultures established in the forest-steppe zone of Siberia. Variation in these characters has been
revealed, which reflects the polymorphic structure of the species and the effect of natural selection on the composition of revealed, which reflects the polymorphic structure of the species and the effect of natural selection on the composition of
populations in new natural-cimatic conditions. populations in new natural-cimatic conditions.
Wood density (D
t), an excellent predictor of mechanical properties, is typically viewed in relation to support against gravity, wind, snow, and other environmental forces. In contrast, we show the surprising extent to which variation in D
t and wood structure is linked to support against implosion by negative pressure in the xylem pipeline. The more drought-tolerant the plant, the more negative the xylem pressure can become without cavitation, and the greater the internal load on the xylem conduit walls. Accordingly, D
t was correlated with cavitation resistance. This trend was consistent with the maintenance of a safety factor from implosion by negative pressure: conduit wall span (b) and thickness (t) scaled so that (t/b)2 was proportional to cavitation resistance as required to avoid wall collapse. Unexpectedly, trends in D
t may be as much or more related to support of the xylem pipeline as to support of the plant.