Tropical Rainforest Gaps And Tree Species Diversity

Tree species coexistence in a Mexican seasonally dry tropical forest

Thesis

Jan 2007

Rebecca J Sykes

p>In this research project, a variety of complimentary techniques have been used to investigate the potential mechanisms that may be maintaining the coexistence of five highly similar interdigitated species from the genus Bursera , within the seasonally dry tropical forest of Chamela, Jalisco, Mexico. The population dynamics, incidences of herbivore damage, plant chemistry, spatial patterns and microhabitat associations of the congeneric species Bursera instabilis, B. arborea, B. fagaroides, B. excelsa, and B. heteresthes were investigated. Several coexistence theories were supported by evidence gathered during this research, where the predictions of those theories were explained by population processes determined by a seed size-seed number trade-off. The theories of patch dynamics, density- and distance-dependent mortality and dispersal limitation were suggested to interact within the larger framework of differential sensitivity storage dynamics. The differential sensitivity storage theory states that the coexistence of common and rare competing species is maintained by differential sensitivity to temporally varying environmental conditions, which results in fluctuations in seedling mortality and thus adult recruitment through time. Trade-offs between growth rate/performance and tolerance to herbivory/shade were suggested to explain the differential sensitivity of species within the genus Bursera . Temporal fluctuations in rainfall, which in turn influences canopy development and thus light conditions at the forest floor, in addition to herbivore pressure were then suggested to be potential environmental drivers of differential sensitivity storage dynamics.</p

Disentangling the impact of nested sources of variability on species growth processes: A mixture of multilevel mixed model approach.

Article

Jun 2024

The understanding of tree growth processes is crucial for promoting sustainable forest management strategies. This is a challenging task in highly biodiverse ecosystems where many tree species are observed on very few individuals and the small sample sizes hinder a good fit of species‐specific models. We propose the use of finite mixture of random coefficient regression models with multilevel nested random effects to infer guild specific fixed and random effects while evaluating the relative importance of the nested sources of variability on goodness‐of‐fit. This approach extends finite mixture of linear mixed model used for longitudinal or single group structured data contexts. A dedicated expectation–maximisation algorithm is introduced for parameter estimation. Simulations are performed for the evaluation of the misspecification of nested‐grouping structures. This work has been motivated by data collected biennially in Central African rainforests from 1986 to 2010. We show the accuracy of the proposed approach in successfully reproducing individual growth processes and classifying tree species into well‐differentiated clusters with clear ecological interpretations. Moreover, results confirm that interindividual variability appears as the most important factor to explain tropical tree species growth process variability from Central Africa forests.

Regeneração natural em clareiras após a colheita florestal na Amazônia Oriental.

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Dec 2022

Floristic composition, growth temperament and conservation status of woody plant species in the Cameroonian tropical rainforests

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Aug 2022

Abstract Introduction Cameroon’s tropical rainforests are nowadays strewn with rural forests maintained by local populations; however, these forests are not officially recognized in the non-permanent forest domain. Rural forests are non-delimited riparian areas within the dense moist forest, reserved for rural housing, agricultural activities and agroforestry practices, freely exploited by the local communities for their livelihood without them having any rights to artisanal and commercial logging. This study aimed at contributing to the flora knowledge and the conservation state of woody plant species in rainforests. The study was carried out in two rural forests located in the Eastern and Southern agroforestry zones of Cameroon. Methods The method adopted for floristic inventories combined a fixed area sampling unit and a variable area sampling unit. Woody individuals with diameter at breast height (dbh)

Livro Biodiversidade flona-resex cap (3)

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Jul 2022

CapítuloLIVRObiodiversidade flona-resex final ebook 0

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Jun 2022

Cap. 11- Peixes em igarapés da Floresta Nacional do Tapajós e Reserva Extrativista Tapajós-Arapiuns

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Jun 2022

Biodiversidade na Floresta Nacional do Tapajós e na Reserva Extrativista Tapajós-Arapiuns

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Jun 2022

Tree regeneration characteristics in limestone forests of the Cat Ba National Park, Vietnam

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Dec 2022

Background The ability of overstory tree species to regenerate successfully is important for the preservation of tree species diversity and its associated flora and fauna. This study investigated forest regeneration dynamics in the Cat Ba National Park, a biodiversity hotspot in Vietnam. Data was collected from 90 sample plots (500 m ² ) and 450 sub-sample plots (25 m ² ) in regional limestone forests. We evaluated the regeneration status of tree species by developing five ratios relating overstory and regeneration richness and diversity. By examining the effect of environmental factors on these ratios, we aimed to identify the main drivers for maintaining tree species diversity or for potential diversity gaps between the regeneration and the overstory layer. Our results can help to increase the understanding of regeneration patterns in tropical forests of Southeast Asia and to develop successful conservation strategies. Results We found 97 tree species in the regeneration layer compared to 136 species in the overstory layer. The average regeneration density was 3764 ± 1601 per ha. Around 70% of the overstory tree species generated offspring. According to the International Union for Conservation of Nature’s Red List, only 36% of threatened tree species were found in the regeneration layer. A principal component analysis provided evidence that the regeneration of tree species was slightly negatively correlated to terrain factors (percentage of rock surface, slope) and soil properties (cation exchange capacity, pH, humus content, soil moisture, soil depth). Contrary to our expectations, traces of human impact and the prevailing light conditions (total site factor, gap fraction, openness, indirect site factor, direct site factor) had no influence on regeneration density and composition, probably due to the small gradient in light availability. Conclusion We conclude that the tree species richness in Cat Ba National Park appears to be declining at present. We suggest similar investigations in other biodiversity hotspots to learn whether the observed trend is a global phenomenon. In any case, a conservation strategy for the threatened tree species in the Cat Ba National Park needs to be developed if tree species diversity is to be maintained.

Effect of Gap Size And Elevation On The Regeneration And Coexistence of Three Tree Species In A Subalpine Coniferous Forest

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Full-text available

Jul 2021

Background: Gap size and environmental gradient have fundamental influence on the tree species coexistence and community assembly. We studied the regeneration and coexistence of three co-dominant tree species in three different gap size (large gap, 201-402 m²; medium gap, 101-200 m²; small gap, 38.8-100 m²) along an elevation gradient (between 3000m and 3500m) in an old-growth forest, on Mount Nadu in southwest China. Results: We found that the photosynthetic photon flux density (PPFD) was positively affected by gap size during the growing season. All three species had a higher regeneration density in large gaps, but the detailed response to treatments for each species depended on its stem size. Gap size had a significant positive effect on the regeneration density of Abies faxoniana small trees and Betula utilis saplings, but had no significant effect on Acer maximowiczii regeneration density. Saplings regeneration density is more sensitive to elevation compared to small trees regeneration density. Large gaps magnified the negative effects of elevation on regeneration density. Our findings indicated that Abies may maintain its regeneration advantage with low-intensity canopy disturbance, and large gap may provide excellent opportunities for broadleaf species (Betula and Acer) establishment and regeneration in this subalpine coniferous forest. Conclusion: Microhabitats heterogeneity controlled by characteristics of forest gaps along an elevation affected regeneration niche difference of tree species, which contributed to species coexistence and community assembly processes.

Grow or die: A 49‐year growth history of a Japanese warm‐temperate tree species

Article

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May 2024

The growth trajectories of trees are not fully understood due to their long life span. We characterized the population dynamics of the canopy tree Castanopsis cuspidata (Thunb.) Schottky in a Japanese warm‐temperate forest over 49 years (1966–2015). Our study was initiated approximately 50 years after our study site was clear‐cut. The forest had a closed canopy for the first 23 years of the study. Strong typhoons in 1991 and 1993 seriously damaged the forest, and since then the forest has been recovering from these disturbances. The diameter distribution of this species was bell‐shaped in 1966, suggesting that the trees emerged simultaneously after the clear‐cut in the 1910s, and the recruitment of trees has remained unchanged since then. The lack of recruitment of C. cuspidata before the typhoon disturbance supports this conclusion. Assuming that the C. cuspidata trees in 1966 were cohorts that were established soon after the clear‐cut, the size differences reflect differences in growth rate, with small trees corresponding to slow growers and large trees corresponding to fast growers. Before the typhoon, slow growers had low survival, and the mortality rate of fast growers was low. Many fast growers were uprooted or snapped by strong winds by the typhoons. However, their mortality rate did not differ from that of slow growers because many slow growers were killed by large fallen trees. The growth of some slow‐growing survivors increased after the typhoon, which allowed them to rapidly reach the canopy. Therefore, the typhoon altered the distribution of canopy trees among slow and fast growers. Survivors experienced faster growth than trees that died during the census period, suggesting that growth rate provides a robust indicator of future survival. Before the typhoon, the survival of fast growers was higher than that of slow growers. This suggests that fast growers disproportionally contribute to reproduction compared with slow growers. However, no recruited tree was observed in this subperiod, suggesting that fast growers made no contribution to reproduction. Fast growers might not play a more significant demographic role than slow growers in this species.

БАЙБАК (MARMOTA BOBAK) И ФЛОРИСТИЧЕСКОЕ РАЗНООБРАЗИЕ ОСТЕПНЕННЫХ ЛУГОВ В БРЯНСКОЙ ОБЛАСТИ

Article

Full-text available

Feb 2024

Показана роль степных сурков, или байбаков, в формировании и поддержании структурного и видового разнообразия остепненных лугов. Зверьки благодаря пастьбе формируют мелкотравные луга в пределах поселения. Трофическая деятельность байбаков сдерживает развитие злакового высокотравья: Bromopsis inermis, Calamagrostis epigeios, Elytrigia repens и др. Без постоянного стравливания крупные злаки формируют ценотически замкнутые группировки и вытесняют большинство слабоконкурентных луговых растений. В течение вегетационного сезона сурки меняют набор поедаемых трав. Это исключает дигрессию мелкотравного луга на поселении. Благодаря роющей деятельности байбаков на лугах появляются бутаны, или сурчины. Уникальные экологические условия на сурчинах способствуют формированию микрогруппировок с преобладанием сухолуговых растений. Кроме того, на бутаны активно внедряются однолетники и двулетники, а также черноольховые, неморальные и бореальные растения, которые не свойственны остепненным лугам.

Recent Trends in Biodiversity of Andaman and Nicobar Islands Chapter-18

Chapter

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Mar 2010

Natural disturbances and the hydrology of humid tropical forests

Article

Full-text available

Sep 2023

Roles of pathogens and mycorrhizae in conspecific negative distance dependency and replacement of tree species in a temperate forest

Article

Sep 2023
FOREST ECOL MANAG

Sensitivity of Optical Satellites to Estimate Windthrow Tree-Mortality in a Central Amazon Forest

Article

Full-text available

Aug 2023

Windthrow (i.e., trees broken and uprooted by wind) is a major natural disturbance in Amazon forests. Images from medium-resolution optical satellites combined with extensive field data have allowed researchers to assess patterns of windthrow tree-mortality and to monitor forest recovery over decades of succession in different regions. Although satellites with high spatial-resolution have become available in the last decade, they have not yet been employed for the quantification of windthrow tree-mortality. Here, we address how increasing the spatial resolution of satellites affects plot-to-landscape estimates of windthrow tree-mortality. We combined forest inventory data with Landsat 8 (30 m pixel), Sentinel 2 (10 m), and WorldView 2 (2 m) imagery over an old-growth forest in the Central Amazon that was disturbed by a single windthrow event in November 2015. Remote sensing estimates of windthrow tree-mortality were produced from Spectral Mixture Analysis and evaluated with forest inventory data (i.e., ground true) by using Generalized Linear Models. Field measured windthrow tree-mortality (3 transects and 30 subplots) crossing the entire disturbance gradient was 26.9 ± 11.1% (mean ± 95% CI). Although the three satellites produced reliable and statistically similar estimates (from 26.5% to 30.3%, p < 0.001), Landsat 8 had the most accurate results and efficiently captured field-observed variations in windthrow tree-mortality across the entire gradient of disturbance (Sentinel 2 and WorldView 2 produced the second and third best results, respectively). As expected, mean-associated uncertainties decreased systematically with increasing spatial resolution (i.e., from Landsat 8 to Sentinel 2 and WorldView 2). However, the overall quality of model fits showed the opposite pattern. We suggest that this reflects the influence of a relatively minor disturbance, such as defoliation and crown damage, and the fast growth of natural regeneration, which were not measured in the field nor can be captured by coarser resolution imagery. Our results validate the reliability of Landsat imagery for assessing plot-to-landscape patterns of windthrow tree-mortality in dense and heterogeneous tropical forests. Satellites with high spatial resolution can improve estimates of windthrow severity by allowing the quantification of crown damage and mortality of lower canopy and understory trees. However, this requires the validation of remote sensing metrics using field data at compatible scales.

Influence of Geographical Aspect and Topography on Canopy Openness in Tropical Rainforests of Sri Lanka along an Altitudinal Gradient

Preprint

Full-text available

Jul 2023

Solar radiation energy is a limiting factor for forest growth in humid tropical environments. Radiation incident on a forest canopy varies with azimuth angle of incident radiation and aspect of the forest terrain. The objective of this work was to determine the influence of the geographical aspect and azimuth of incident radiation on the canopy structure of tropical rainforests of Sri Lanka (TRFSL). Hemispherical photography was used to capture canopy images of TRFSLs in ten permanent sampling plots across an altitudinal range from 117 m to 2132 m above mean sea level. Fraction of visible sky (V sky ) in 144 sectors of the canopy hemisphere, defined by 18 zenith angle (ZnA) x 8 azimuth angle (AzA) segments, was determined using image analysis. Canopy openness, quantified as V sky of the overall hemisphere, increased with increasing altitude. Canopy leaf area index, decreased linearly with altitude and had a negative relationship with V sky . Canopy openness of the top one-third (ZnA=0°–30°) of the hemisphere (V sky(0–30) ) was significantly (p<0.05) lower on the east (AzA=90°) than on the west (AzA=270°) in a majority of plots. Similarly, V sky(0–30) was lower on the northern (AzA=0°) than the southern (AzA =180°) canopy segment. These patterns were altered in plots where nearby mountains and slope aspect of the plot influenced incident radiation. These observations suggest a hypothesis that canopies of TRFSL are structured to maximize radiation capture by allocating more leaf area, and therefore having lower canopy openness, on sides of the canopy which face directions of greater radiation receipt.

Sensitivity of Optical Satellites to Estimate Windthrow Tree-Mortality in a Central Amazon Forest

Preprint

Full-text available

May 2023

Windthrow (i.e., trees broken and uprooted by wind) is a major natural disturbance in the Amazon. Images from medium-resolution optical satellites (mostly Landsat) combined with extensive field data have allowed researchers to assess patterns of tree mortality and monitor forest recovery over decades of subsequent succession in different regions. Although satellites with high spatial-resolution have become available for the Amazon in the last decade, they have not yet been employed for the mapping and quantification of windthrow tree-mortality. Here, we address how increasing the spatial resolution of satellites affects plot-to-landscape estimates of windthrow tree-mortality. We combined forest inventory data with Landsat 8 (30 m pixel), Sentinel 2 (10 m), and WorldView 2 (2 m) imagery over an old-growth forest in the Central Amazon that was disturbed by a single windthrow event in November/2015. Remote sensing estimates of tree mortality were produced with Spectral Mixture Analysis and analyzed together with forest inventory data using Generalized Linear Models. Windthrow tree-mortality measured in 3 transects (30 subplots) crossing the entire disturbance gradient was 26.9 ± 11.1% (mean ± 95% CI). Based on this ground truth, the three satellites produced reliable and statistically similar estimates (from 26.5% to 30.3% windthrow tree-mortality, p<0.001). The mean-associated uncertainties decreased systematically with increasing spatial resolution (i.e., from Landsat 8 to Sentinel 2 and WorldView 2). However, the overall quality of fit of models showed the opposite pattern, which may reflect the influence of crown damage not accounted for in our field study, and fast-growing regeneration of leaf area. Among the satellites studied, Landsat 8 most accurately captured field observations of variations in tree mortality across the disturbance gradient (i.e., lower under- and/or overestimation from undisturbed to extremely damaged forest). Although satellites with high spatial-resolution can refine estimates of windthrow severity by allowing the quantification of individual tree damage and mortality, our results validate the reliability of Landsat imagery for assessing patterns of windthrow tree-mortality in dense and heterogeneous tropical forests. Although high-resolution imagery may improve estimates of tree damage and mortality, these should be validated using field data at compatible scales.

MOGNO AFRICANO (Khaya senegalensis (Desr.) A. Juss.) TECNOLOGIAS DE PLANTIO E UTILIZAÇÃO

Book

Full-text available

May 2023

madeira do mogno brasileiro (Swietenia machophylla King) é hoje uma das mais valorizadas economicamente, alcançando valores de mercado superiores as outras arbóreas, sendo utilizada para diversos fins. De modo geral, a espécie possui dificuldade de regeneração natural e de estabelecimento em reflorestamentos, tendo como principal praga larvas de Hypsipyla grandella Zeller. Entretanto, as espécies do gênero Khaya apresentam grande potencial no reflorestamento devido à tolerância a esta praga. Portanto, os mognos africanos (Khaya spp.) representam uma alternativa silvicultural e madeireira ao mogno (Swietenia macrophylla King) encontrado na Amazônia e protegido por lei, pois as espécies Khaya spp são as árvores produtoras de madeiras nobres mais procuradas para plantios, tanto em pequenas como em grandes propriedades no Brasil. No nosso país, os mognos africanos apresentam rápido crescimento e proporcionam uma madeira de excelente qualidade, principalmente para a indústria moveleira e de laminados. Entre as seis espécies existentes, denominadas: Khaya senegalensis, Khaya anthotheca, Khaya grandifoliola, Khaya ivorensis, Khaya nyasica e Khaya madagascarensis, a madeira da espécie Khaya senegalensis é classificada como uma das melhores madeiras de mogno africano, ademais pode suportar uma estação seca de 4 a 7 meses. A madeira é moderadamente dura e de densidade média. O cerne é marrom-avermelhado profundo com um tom arroxeado e a aparência atraente a torna uma das madeiras mais preferidas principalmente para as indústrias de móveis, naval e de construção civil. Seu cultivo iniciou-se no Norte do Brasil, em razão de iniciativas da Embrapa Amazônia Oriental, difundindo-se pelo Sudeste (especialmente Minas Gerais) e Centro-Oeste, inclusive em áreas do Cerrado, onde informações sobre seu manejo tem sido demandada para órgãos de extensão e pesquisa. Nesta revisão, são abordados temas como origem, importância econômica, distribuição geográfica, descrição botânica e sistemática, propagação vegetativa, exigências climáticas, manejo florestal, doenças e pragas, idade de corte das árvores de mogno africano, entre outros. Em razão disso, este livro escrito em português pode ser um manual útil para aquele que decidir plantar essa árvore e conhecê-la em maior profundidade, o livro "Mogno africano (Khaya senegalensis (Desr.) A. Juss.): Tecnologias de plantio e utilização”, será de grande interesse e ajuda para o produtor que necessita pôr em prática as várias tecnologias abordadas no mesmo

Detecting forest canopy gaps using unoccupied aerial vehicle RGB imagery in a species‐rich subtropical forest

Article

Full-text available

May 2023

Accurate and efficient detection of canopy gaps is essential for understanding species regeneration and community dynamics in forests. Unoccupied aerial vehicles (UAVs) equipped with visible light (e.g., RGB) cameras have the potential to be one of the most cost‐effective approaches for detecting gaps. However, current gap‐detection methods based on spectral, textural, and/or structural information derived from UAV RGB imagery are unreliable in species‐rich forests with complex terrain due to high spectral complexity and topographic shadowing. Here, we compared the performance of four methods, including pixel‐based supervised classification (PBSC), object‐based classification (OBIA), Canopy Height Model thresholding classification, and HSTAC [a novel method we developed which combines Photographic Height (H), Spectral (S), and Textural (T) information for Automatic Classification (AC)] for characterizing canopy gaps in a 20‐ha permanent subtropical forest plot of eastern China. All classification results were evaluated through a comparison with canopy gaps detected from both field surveys and UAV‐borne LiDAR data. Among the four classification methods, HSTAC performed best in terms of detection efficiency (96% overall accuracy when compared to field data and 85% when compared to the LiDAR data), classification accuracy (3–18% improvement compared to alternative methods), and speed (1–1.5 h faster on the same machine). Of the four topographic factors (elevation, slope, aspect, and convexity), elevation was the one that most affected the accuracy of canopy gap detection. The errors of PBSC classification mainly came from the gaps at low elevations, while OBIA located the position of gaps well but overestimated their sizes. Overall, HSTAC avoids many of the inherent limitations of current state‐of‐the‐art methods and can accurately map canopy gaps in diverse subtropical forests with complex terrain. Our study provides a suitable way for long‐term forest canopy monitoring, real‐time applications, and contributes to a better understanding of forest plant community assembly and succession dynamics.

Diversity Patterns of Vascular Plant Groups Along Gradients of Elevation and Disturbance in Mexico

Chapter

Apr 2023

In this work, we contribute to the knowledge of how two environmental gradients (elevation and forest-use intensity) interactively affect the tropical plant diversity of six different vascular plant groups (trees, shrubs, lianas, terrestrial herbs, epiphytes, and ferns). The results were obtained in the frame of the interdisciplinary research project “BIOVERA,” which aims at documenting and understanding biodiversity patterns along gradients of elevation, climate, soil, and disturbance along an eleva tional transect at the Cofre de Perote mountain in central Veracruz, Mexico.

Canopy openness and soil conditions explain community structure and diversity in a tropical seasonal forest in south-eastern Brazil

Article

Full-text available

Dec 2021

In tropical semi-deciduous forests, where 20-50 % of canopy trees shed their leaves in the dry season, species with varying degrees of leaf deciduousness share the same space and resources. Here, we describe the tree community in a 10.24-ha plot to assess whether small-scale variation in canopy structure and soil conditions are associated with changes in tree community structure, diversity, and composition. We sampled 11,585 individuals with diameter at breast height ≥ 4.8 cm belonging to 146 species. Plot density (1,129 trees ha⁻¹) and basal area (24.81 m² ha⁻¹) were smaller than other similar forests, which may be due to an old wind disturbance. For 8.96 ha, we evaluated the relationship between abiotic factors and community descriptors using regression models. Results varied within size classes, but canopy openness was associated with changes in the community structure and diversity, and soil fertility did not affect species diversity. Tree density, basal area, and diversity were smaller in areas with more canopy gaps. Tree density and basal area increase with phosphorus availability, while the density of deciduous trees increased with canopy openness and base saturation. Thus, we found evidence that canopy openness and soil can explain small-scale variations of forest structure and diversity. Keywords: Atlantic Forest; environmental heterogeneity; permanent plot; regression models; species richness

Coarse Woody Debris in Monsoon Tropical Forests of Vietnam

Article

Dec 2022

Evaluating gap characteristics and their effects on regeneration in Sitapahar forest reserve, Bangladesh

Article

Full-text available

Oct 2022
EUR J FOREST RES

Natural regeneration and forest successional development are influenced by gap formation in forest stands. Nonetheless, there are limited studies that provide quantitative information on the influence of gaps on forest regeneration. We evaluated characteristics of inner and outer canopy gaps and their effects on natural regeneration in 40 canopy gaps in Sitapahar forest reserve of Bangladesh. A total of 50 individuals of 27 gapmaker tree species were found, of which 58% were formed by logging and the rest by natural damages. Elliptical shape represented 53% of the gaps followed by circular and rectangular gaps. The mean area of the outer and inner gaps was 50.1 ± 8.6 and 20.0 ± 3.0 m2, respectively. Gap formation types and shapes did not vary significantly between outer and inner gaps, while the mean gap area in older gaps was significantly higher than in new gaps. In comparison with outer gaps, mean densities of seedlings and saplings in the inner gaps were significantly higher, which is probably because of the closeness to seed trees. The diversity index of regenerating species and their height and collar diameter did not vary significantly between the inner and outer gaps. Positive, but weak relationships of gap area with subcanopy tree density and diversity were found. Since gaps were found dominated by few light-demanding tree species such as Brownlowia elata, Lithocarpus acuminata, Lithocarpus polystachya, and Macaranga denticulate, it is suggested that larger gaps need to be replanted with a combination of light-demanding and shade-tolerant native trees.

A general hypothesis of forest invasions by woody plants based on whole‐plant carbon economics

Article

Full-text available

Oct 2022
J ECOL

Although closed‐canopy forests are characterized by low‐light availability and slow population dynamics, many are under threat from non‐native, invasive woody species that combine high colonization ability and fast growth potential with high low‐light survival. This ‘superinvader’ phenotype contravenes expected trade‐offs predicted by successional niche theory, posing a challenge to both invasion and forest succession theory. We propose a parsimonious conceptual model based on the whole‐plant light compensation point (WPLCP) that, across a variety of plant strategies and growth forms, can explain greater competitive abilities of forest invaders in the context of both high‐light growth rate and shade tolerance. The model requires only that non‐native species experience relatively fewer carbon costs than native species, enabling resource‐acquisitive species to establish in low‐light conditions. We review evidence for lower carbon costs in invasive species resulting from (1) enemy release, (2) recent environmental changes that favour less stress‐tolerant phenotypes and (3) phylogenetically constrained native floras. We also discuss implications of invader shade tolerance in the context of other life‐history strategies that, combined with canopy disturbances, facilitate their rapid numerical dominance. Synthesis. An invasion framework driven by carbon dynamics suggests renewed focus on whole‐plant carbon costs, including below‐ground respiration and tissue turnover, which are rarely measured in functional studies of forest invaders.

Evolutionary history constrains heat tolerance of native and exotic tropical Zingiberales

Article

Full-text available

Oct 2022
FUNCT ECOL

Tropical wet forest plants experience relatively stable temperatures throughout the year. However, tropical forests represent a mosaic of habitats characterized by different temperatures. Heat tolerances are expected to be adapted to temperatures specific to their habitats. Although heat tolerance of species sharing similar environments is expected to be similar, it is also possible that heat tolerance is constrained by evolutionary history because closely related species usually display similar physiologies. When exotic species are introduced to novel communities, colonization may be facilitated by their previous adaptation to high temperatures and other physiological, genetic and demographic traits, which may grant them some competitive advantage. Increasing temperatures may represent a strong environmental filter affecting community assembly, and higher heat tolerances could facilitate the persistence of exotic species in novel environments. Using a community of 32 native and 7 exotic Zingiberales species from different tropical habitats in Costa Rica, Central America, we aim to answer the following questions: (a) does evolutionary history constrain heat tolerance? (b) do plants in the same habitat display similar heat tolerances? (c) do the heat tolerances of exotic species differ from those of native species? We measured temperature‐dependent changes in photosynthetic fluorescence to determine the temperature at which the first sign of damage to photosystem II is observed (T15), and the temperature at which the fluorescence of photosystem II is reduced by 50% (T50). Using a community phylogeny, we tested for phylogenetic signal in T15 and T50. In addition, we tested for differences in heat tolerance among Zingiberales from old growth, secondary forests and open areas, as well as between native and exotic species. Our results support (a) a significant phylogenetic signal (Pagel's λ) for both T15 and T50, (b) communities from open areas displayed similar photosynthetic heat tolerance compared to species from old growth and secondary forests, and (c) exotic Zingiberales are marginally tolerant to high temperatures than native species, but only for T15. Our results suggest that evolutionary history constraints heat responses of native and exotic Zingiberales in a warming world. Read the free Plain Language Summary for this article on the Journal blog.

Vertical stratification patterns of tropical forest vertebrates: a meta‐analysis

Article

Full-text available

Sep 2022

Tropical forests harbour the highest levels of terrestrial biodiversity and represent some of the most complex ecosystems on Earth, with a significant portion of this diversity above ground. Although the vertical dimension is a central aspect of the ecology of forest communities, there is little consensus as to prominence, evenness, and consistency of community‐level stratification from ground to canopy. Here, we gather the results of 62 studies across the tropics to synthesise and assess broad patterns of vertical stratification of abundance and richness in vertebrates, the best studied taxonomic group for which results have not been collated previously. Our review of the literature yielded sufficient data for bats, small mammals, birds and amphibians. We show that variation in the stratification of abundance and richness exists within and among all taxa considered. Bat richness stratification was variable among studies, although bat abundance was weighted towards the canopy. Both bird richness and abundance stratification were variable, with no overriding pattern. On the contrary, both amphibians and small mammals showed consistent patterns of decline in abundance and richness towards the canopy. We descriptively characterise research trends in drivers of stratification cited or investigated within studies, finding local habitat structure and food distribution/foraging to be the most commonly attributed drivers. Further, we analyse the influence of macroecological variables on stratification patterns, finding latitude and elevation to be key predictors of bird stratification in particular. Prominent differences among taxa are likely due to taxon‐specific interactions with local drivers such as vertical habitat structure, food distribution, and vertical climate gradients, which may vary considerably across macroecological gradients such as elevation and biogeographic realm. Our study showcases the complexity with which animal communities organise within tropical forest ecosystems, while demonstrating the canopy as a critical niche space for tropical vertebrates, thereby highlighting the inherent vulnerability of tropical vertebrate communities to forest loss and canopy disturbance. We recognise that analyses were constrained due to variation in study designs and methods which produced a variety of abundance and richness metrics recorded across different arrangements of vertical strata. We therefore suggest the application of best practices for data reporting and highlight the significant effort required to fill research gaps in terms of under‐sampled regions, taxa, and environments.

Managed vs. unmanaged Fagus orientalis Lipsky forests: Structure and diversity of natural regeneration in northern Iran

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Full-text available

Aug 2022

The predominant natural disturbance regime within an old-growth Oriental beech (Fagus orientalis Lipsky) forest has been imitated in order to continue the forest cover. It is unclear how much the silvicultural characteristics of regeneration in a managed forest differ from those in an unmanaged old-growth forest subject only to natural dynamics. In this study, we compared important quantitative (e.g. height, collar diameter, crown width, length of spring shoot on the main stem and length of the uppermost internodes) and qualitative (e.g. healthy, mode of branching and stem form) silvicultural characteristics of beech saplings within the gaps between an unmanaged old-growth Oriental beech compartment and a managed forest in the northern Iran ten years after a single harvest entry using a single-tree selection. Canopy gaps larger than 100 m<sup>2</sup> with visible remnants of gapmakers (i.e. stumps) were included in this study. The saplings’ characteristics of both compartments were within typical ranges for an old-growth beech forest. Small, but important differences were also observed. The value of beech saplings’ density in the managed compartment (4.9 ± 0.7 SE) was significantly (P < 0.05) higher than the unmanaged one (3.4 ± 0.6 SE). Conversely, the value of the Menhinick Richness index in the unmanaged one (0.96 ± 0.05 SE) was significantly (P < 0.01) higher than the managed compartment (0.80 ± 0.04 SE). The sapling spring shoot length in the unmanaged compartment (13.3 ± 1.7 SE) was also significantly (P < 0.01) higher than the managed one (7.3 ± 0.7 SE). Relying on beech trees in a managed compartment will hamper the stability of future forest stands. The imitation of the old growth forest must be complete. To increase the resistance of the forest stands to adverse conditions, pay attention to the tree species richness at the time of marking.

Herramientas para abordar la Restauración ecológica de áreas disturbadas en Colombia

Article

Aug 2022

Este artículo presenta una revisión sobre los temas de la ecología de la restauración, la restauración ecológica de áreas disturbadas y la aplicación de dichos conceptos para abordar la restauración ecológica de los ecosistemas disturbados, en especial los terrestres. Los Andes colombianos comprenden diversos ecosistemas que se encuentran fuertemente sometidos a la presión antrópica por tratarse de la región más altamente poblada del país. En consecuencia, la colonización y establecimiento del hombre en la montaña genera una gran cantidad de disturbios que han dado origen a un variado y numeroso repertorio de áreas disturbadas, entre las que sobresalen bosques fragmentados, parches con ausencia de vegetación, áreas construidas, áreas cultivadas y pastoreadas, áreas con procesos erosivos, ríos y quebradas con disminución de caudales, suelos y cuerpos de agua contaminados, entre otros. La restauración ecológica de áreas alteradas obliga al diseño e implementación de tácticas y técnicas de restauración basadas en conceptos claros y aplicables de la ecología, de tal modo que contribuyan, con el tiempo, a desarrollar una estrategia de restauración que responda al establecimiento de ambientes degradados y garantice su sostenibilidad. Para abordar la restauración ecológica es necesario considerar los niveles de complejidad con un enfoque jerárquico supraorganísmico que involucre escalas espaciales y temporales del área disturbada; las etapas a considerar comprenden: a) Definición del objetivo del proyecto, b) caracterización del área disturbada, c) implementación de las técnicas y procedimientos más adecuados, y d) la definición de las variables para realizar el seguimiento.

Assessment of Coverage Percentage, Biomass, and Photosynthetic Pigments of Bryophytes in Kanasar Forest Range, Uttarakhand, India

Article

Full-text available

Aug 2022

The effects of forest gaps can be a source for the opportunistic bryophytes to manage their diversity. In view of this objective, the present study deals with an assessment of the effect of forest canopy gaps on bryophyte diversity, abundance, biomass, and photosynthetic pigments in some dominant species of bryophytes. We believe that forest gaps provide opportunity to some opportunistic species to survive in the existing environment conditions. Our results indicate that the bryophyte diversity was found higher in gap areas as compared to non-gap areas indicating the rapid invasion of opportunistic species and the role of gaps in maintaining species diversity. Bryum capillare and Brachythecium buchananii were found to be the dominant taxa in the forest canopy gaps and non-gap, respectively. In spring season, the amount of chlorophyll-a, chlorophyll-b, and total carotenoids was found to be 15.37 µg/mL, 14.87 µg/mL, and 7.87 µg/mL, respectively, in B. buchananii; however, in the rainy season, the contents of chlorophyll-a and chlorophyll-b increased (23.12 µg/mL and 17.41 µg/mL, respectively), while total carotenoids 7.74 µg/mL decreased. Similar difference was recorded in B. capillare in which lower amounts of chlorophyll-a (14.24 µg/mL), chlorophyll-b (10.03 µg/mL), and total carotenoids (9.81 µg/mL) were recorded in spring season as compared to that of rainy season (20.11 µg/mL, 16.63 µg/mL, and 9.65 µg/mL, respectively). The total bryophyte biomass was found significantly higher (25.58 g/m2) in the canopy gap areas as compared to non-gap areas (20.44 g/m2). These results indicate that the forest gaps play a positive role in shaping the bryophyte diversity and performance.

Liana effects on tree functional groups and carbon balance in a lowland tropical forest, Panama and an analysis of progress in remote sensing of lianas

Article

Jul 2022

Ashley David Caunt Proctor

1. Lianas (or vines) are woody climbers that root in the ground and utilise the structure of neighbouring trees to ascend into the forest canopy. These plant forms are found in forests globally, although they are particularly prevalent seasonal and lowland forests of the neotropics where they make up a significant proportion of woody species and stems. Lianas infest host trees and can dominate forest canopies, often described as structural parasites, lianas compete intensely with trees for sunlight and belowground resources without investing in their own supporting structure. 2. Research interest in lianas has increased substantially in recent decades, though they remain understudied compared to other plant forms. Chapter 1 reviews the increasingly comprehensive and geographically broad evidence base documenting the competitive effect of lianas upon host trees. Liana infestation has a significant and detrimental impact on tree growth, mortality, reproduction, and regeneration. Ultimately this reduces the capacity of trees to sequester and store carbon, a globally important ecosystem service provided by tropical forests. Furthermore, some evidence suggests that lianas are disproportionately affecting shade-tolerant carbon dense tree genera, contributing to a decline in these species. Reports of increasing liana abundance in the neotropics adds to the urgency for further research into the extent, magnitude, and mechanisms by which lianas effect the carbon balance in tropical forests. 3. Studying tropical forest canopies is challenging, as such relatively little is known about the distribution of lianas in forest canopies. Remote sensing is an emerging research method that has overcome some of the shortfalls associated with standard field surveys and can provide new and critical insights into liana ecology. Chapter 2 provides the first systematic assessment of the progress in the use of remote sensing to further understand the (i) spatial and temporal distributions, (ii) structure and biomass, (iii) responses to environmental conditions, and (iv) diversity, of lianas. The possibilities offered by new and future advances in remote sensing technology to study lianas, and the further data requirements needed, are then considered. For unanswered research questions to be resolved, liana ecology needs remote sensing. 4. Chapter 3 is the first study to report findings from a large-scale liana removal experiment for which there is more than 3-4 years of data. I consider eight census years of data from an ongoing liana-removal experiment in Gigante, Panama to address the paucity of research into how lianas impact carbon accumulation in trees with differing life histories and functional traits. Tree biomass growth was 49.21% lower in liana-infested plots over the eight-year period. This is attributed to a growth release in low wood density pioneer species in the four years after removal, which shifts towards high wood density shade tolerant species dominating growth contributions to overall forest carbon in the latter four census years. My findings also support the notion that severity of crown infestation dictates the magnitude of liana effect on tree biomass growth. This study highlights the need to quantify the contribution of species functional groups to forest carbon balance in order to better understand potential future liana effects. With reports of increasing liana abundance, my findings present a worrying picture of the resilience of tropical forests to persist as a functioning global carbon sink. 5. Synthesis. Our understanding of liana ecology and the relationship between these plant forms and carbon balance in tropical forests has increased rapidly. Observational studies, removal experiments, repeated plot censuses and the rapidly evolving applications of remote sensing have provided new insights into the nature of lianas and their interactions with the tropical forests they infest. This study adds to these foundations for future liana research by presenting a thorough review of existing literature, a critical analysis of the integration of remote sensing and an assessment of disproportionate lianas effects on tree functional groups. With the current state of tropical forest decline, urgent knowledge gaps must be addressed now more than ever.

EVALUATION OF FOREST STRUCTURE, COMPOSITION OF COMMERCIAL SPECIES, STAND GROWTH RATE AND VOLUME AMONG CHRONOSEQUENCE STAND AFTER LOGGING IN BORNEO, SARAWAK

Article

Full-text available

Jun 2022

The study on growth rate and yield are some of the parameters in forest dynamics. The information on these aspects can help to infer better future timber production in a managed tropical rainforest helping in achieving sustainable forest management policy. However, information on these aspects of tropical rainforest in Malaysia is scarce, especially in Sarawak. This study was carried out to evaluate the forest stand structure, stand growth, and yield at Forest Management Unit (FMU), Bintulu, Sarawak among chronosequence stand after logging. Five study plots, 16 (15 years after logging), 17 (undisturbed), 18 (11 years after logging), 19 (21 years after logging) and 20 (7 years after logging) were established. Tree diameter at breast height (DBH) ≥ 10 cm and height measurements were enumerated and recorded. The study showed that non-Dipterocarp species dominated in all plots in terms of the number of trees. Dipterocarpaceae family dominated the understorey, main canopy, and emergent layers. Plot 17 shows the lowest growth rate of 0.28 cm year-1 while plot 18 and 19 have the highest growth rate of 0.59 cm year-1 respectively. Dipterocarp groupings of commercial and non-commercial showed higher growth compared to non-Dipterocarp tree species. Plot 17 and 18 showed the highest and lowest mean volume of 277.96 m 3 /ha and 150.86 m 3 /ha. Commercial Non-Dipterocarp group gave higher tree volume yield than the other groupings. This study suggested that there are differences in terms of forest structure, growth rate and yield performance based on different years after logging. This indicates that logging activities affects the condition of the forest stand and longer monitoring of the sites should be applied to further understand these aspects of forest dynamics.

Global variation in diversification rate and species richness are unlinked in plants

Article

Full-text available

Jul 2022

Species richness varies immensely around the world. Variation in the rate of diversification (speciation minus extinction) is often hypothesized to explain this pattern, while alternative explanations invoke time or ecological carrying capacities as drivers. Focusing on seed plants, the world’s most important engineers of terrestrial ecosystems, we investigated the role of diversification rate as a link between the environment and global species richness patterns. Applying structural equation modeling to a comprehensive distribution dataset and phylogenetic tree covering all circa 332,000 seed plant species and 99.9% of the world’s terrestrial surface (excluding Antarctica), we test five broad hypotheses postulating that diversification serves as a mechanistic link between species richness and climate, climatic stability, seasonality, environmental heterogeneity, or the distribution of biomes. Our results show that the global patterns of species richness and diversification rate are entirely independent. Diversification rates were not highest in warm and wet climates, running counter to the Metabolic Theory of Ecology, one of the dominant explanations for global gradients in species richness. Instead, diversification rates were highest in edaphically diverse, dry areas that have experienced climate change during the Neogene. Meanwhile, we confirmed climate and environmental heterogeneity as the main drivers of species richness, but these effects did not involve diversification rates as a mechanistic link, calling for alternative explanations. We conclude that high species richness is likely driven by the antiquity of wet tropical areas (supporting the “tropical conservatism hypothesis”) or the high ecological carrying capacity of warm, wet, and/or environmentally heterogeneous environments.

Modalités d'occupation de l'espace par les arbres en forêt guyanaise

Thesis

Full-text available

Jan 1997

Philippe Birnbaum

Diplôme : Dr. d'Université

ESTRUTURA GENÉTICA E FENOLOGIA DE ESPÉCIES RARAS DE Couratari spp. (LECYTHIDACEAE) NA AMAZÔNIA CENTRAL NADJA LEPSCH -CUNHA Bióloga

Thesis

Full-text available

Jun 2022

Effects of Gaps on Soil Nutrients and Soil Microbial Carbon in a Pinus massoniana Forest, Southwestern China

Article

May 2022
POL J ENVIRON STUD

Identification of the Meteorological Variables Influencing Evapotranspiration Variability Over Florida

Article

Full-text available

May 2022
ENVIRON MODEL ASSESS

Evapotranspiration (ET) plays an important role in agricultural water management and crop modeling. The highest mean annual ET values (889–1016 mm) in the United States (US) occur in Florida where there is a combination of ample rainfall (R) and warm air temperatures. Therefore, it is crucial to know the synergistic influence of meteorological variables (MV) on ET variability. This study aims to evaluate how reference evapotranspiration (ET0) over Florida from 2008 to 2018 was influenced by MV using simultaneous changes in all variables. These changes were evaluated interannually, seasonally, monthly, and daily using trend analysis. We used weather information including R, relative humidity (RH), solar radiation (SR), wind, and temperature parameters as well as ET0 from 33 synoptic stations over Florida recorded by the Florida Automated Weather Network (FAWN). Results of this study showed that SR had the strongest positive annual correlation with ET0 for all climate regions over Florida. However, temporal analysis showed that during December and January, temperature was the dominant factor to control variations of ET0 which was highly consistent with anomalies of ET0 and temperature parameters in December. The correlation coefficients between ET0 and RH were negatively higher than −0.6 from May to September, compared to the entire year, where RH was negligible (between −0.1 and −0.2). The significant trend of air and soil temperature, SR, and RH might be considered as an early alarm system for climate variability over Florida. Finally, sensitivity analysis revealed that ET0 changed at least 1% for 16–18% variations of MV in 67% of the weather stations (22 stations); this range (16–18%) can be assigned as an average range to force ET0 to change at least 1% across Florida. The results of this study can be used as a guideline to assess the annual, seasonal, and monthly relationships between the most influential MV and ET0 across Florida, as a source to identify the most sensitive MV in the modeling of ET related studies, and as the base to develop climate-based management plans for agricultural water management.

Removal of non-native trees fosters but alone is insufficient for forest regeneration in Hawaiʻi

Article

Aug 2022
FOREST ECOL MANAG

Across the globe, non-native plant species have become abundant in many tropical forests, resulting in altered patterns of biological diversity and species composition, and impacting important ecosystem functions. However, long-term experimental research on the efficacy of non-native tree removal for tropical forest restoration remains limited. We investigated the removal of non-native tree species in a mesic tropical forest in Hawaiʻi, where rates of endemism and endangerment of plant species is high and multiple non-native tree species are abundant. As a collaboration between resource managers and researchers, we tested the effects of non-native tree removal on overstory and understory metrics of restoration using three restoration approaches: “total cut” (cutting all non-native trees); “girdle” (girdle of all non-native trees); and “selective cut” (cutting approximately 50% of non-native trees). Prior to removal, we established permanent plots (four 10 × 10 m plots per restoration treatment, with 10 1 × 1 m subplots in each), then monitored them over 10 years. Across all treatments, canopy openness increased significantly post restoration, peaked after three years, then decreased to pre-treatment levels or lower. The increase was largest for the total cut treatment, but there was large variation within treatments. By the end of the experiment, the total cut and girdle treatments performed similarly for all our metrics of restoration, including survival, growth, density, and basal area of native trees; density and richness of native species in the understory; and total weed biomass. The selective treatment performed worse, showing lower relative gains in basal area of native trees and density of native understory individuals. Overall, tree removal was effective in restoring a native canopy. However, understory native species richness and density remained at pre-treatment levels, likely due to limited seed dispersal, seed predation by non-native rodents, and continued competition from non-native herbaceous species. Nonetheless, subplots with the best starting conditions performed the best. More intensive and longer-term weeding of non-native species in the understory, focused on areas with the best starting conditions and combined with out-planting of native seeds, seedlings and/or saplings, is likely necessary to foster effective native species regeneration. Overall, our research shows that removal of non-native trees using the total cut and girdle techniques can foster native forest restoration in the mesic forests of Hawaiʻi, but that on-going long-term management in the understory is critical.

Dinâmica e trajetórias da sucessão secundária na Amazônia central

Article

Full-text available

Mar 2021

O histórico de uso do solo é fator determinante da sucessão secundária na Amazônia central, levando ao estabelecimento de comunidades de plantas com estrutura, composição florística, biomassa e dinâmica distintas. A utilização do fogo para renovação de pastagens compromete o potencial regenerativo dessas áreas, que, quando abandonadas, são dominadas pelo gênero Vismia e colonizadas por poucas espécies, resultando em florestas secundárias pouco diversificadas nas quais a sucessão permanece estagnada. Uma vegetação mais rica e dominada pelo gênero Cecropia coloniza áreas com histórico de uso menos intensivo, permitindo o rápido desenvolvimento da sucessão. Embasado nos conhecimentos adquiridos ao longo de duas décadas de estudo, discutimos aspectos práticos relacionados ao potencial e aos custos do manejo da sucessão secundária para a restauração dos serviços ambientais e como forma de aliar a geração de renda à redução do desmatamento na região. O manejo do dossel e os plantios de enriquecimento mostraram-se técnica e economicamente viáveis em capoeiras de Cecropia, mas capoeiras dominadas por Vismia requerem o desenvolvimento de propostas de manejo alternativas para sua restauração. Trabalhos em desenvolvimento pelo Projeto Pioneiras, objetivando investigar as trajetórias sucessionais em regiões distintas da Amazônia e analisar os efeitos das mudanças climáticas sobre as florestas secundárias, são apresentados e discutidos no final.

Stasis in forest regeneration following deer exclusion and understory gap creation: A 10‐year experiment

Article

Full-text available

Apr 2022
ECOL APPL

Chronically elevated ungulate browse pressure in temperate forests worldwide often generates ecological legacies characterized by low plant diversity and contributes to the formation of dense, nearly monodominant, and highly recalcitrant layers of understory vegetation. Once established, these recalcitrant layers combined with continued browsing may jointly constrain tree establishment and diversity so completely that understory recovery may be unattainable without mitigating browse pressure, the recalcitrant layer, or both. Here, we investigate the independent and synergistic effects of both white‐tailed deer (Odocoileus virginianus) browsing and hay‐scented fern (Dennstaedtia punctilobula) competition on tree regeneration in a 10‐year experiment. Specifically, we examine how tree seedling establishment, growth, and composition are filtered by fern cover versus fern removal (gaps), browser presence versus absence (exclosures), and their combined effects during 10 years at three hardwood forest sites in Pennsylvania, USA. Fern gaps enhanced establishment for multiple tree species, increasing seedling density and diversity, particularly in the first 3 years post‐treatment, and enhancing richness (≤1 species) over the course of the experiment. Excluding deer for a decade increased the height growth of other regeneration and altered species composition, but had no effect on diversity, richness, and density. Notably, we observed higher Prunus serotina seedling densities outside exclosures, possibly due to greater secondary dispersal. We argue that browsing legacies in second growth forests established at the turn of the last century created two conditions inimical to diverse forest regeneration: an overstory dominated by two species, P. serotina and Acer rubrum (86% of basal area), and a dense recalcitrant understory layer dominated by a native fern. The first condition limits propagule supply, the second strongly filters seedling establishment, and both create impoverished forest understories composed of few individuals and species. In undisturbed forest understories, the inertia toward impoverishment was sustained across the decade even where browsing was eliminated. Consequently, stand replacing disturbances (whether natural or anthropogenic) that disrupt the understory layer and reinitiate succession may be necessary to propel forests out of their current stasis and down a pathway leading to greater diversity.

Phenology and Germination of the Chonta Palm, Astrocaryum gratum, in a Sub-montane Forest

Article

Full-text available

Aug 2011

Enzo Aliaga- Rossel

Chonta palm (Astrocaryum gratum) is found in sub-montane neotropical forests, and its basic biology has been little studied. The phenology of Astrocaryum gratum was observed during 25 months in Madidi National Park and Pilón Lajas Biosphere Reserve and Indigenous Territory (Bolivia). The effect of light availability on seed germination of Chonta was also evaluated. The percentage of emerging seeds regardless of whether they were in the shade or sun was not significant; however, buried seeds germinate in higher proportion than ones left uncovered. Astrocaryum gratum plays an important role as a food resource for wildlife, affecting its distribution and movement, and therefore must be considered when designing wildlife management plans.

Leaf functional traits predict shade tolerant tree performance in cloud forest restoration plantings

Article

Full-text available

Feb 2022
J APPL ECOL

Restoration of tropical montane cloud forest (TMCF) landscapes is urgently required. Assisting the regeneration of endangered and shade tolerant tree species is essential for both the recovery of this vulnerable group and of ecological processes. However, there is limited species‐specific information regarding tree performance under different disturbance conditions with which to implement effective interventions. We assessed the performance of shade tolerant tree seedlings in restoration plantings under different disturbance settings and determined whether leaf mass area (LMA) and leaf dry mass content (LDMC)—functional traits typically associated with resource capture or stress tolerance—could serve as predictors of survival and growth among species. Since conservative leaf morphological traits can maximize survival, we expected species with higher LMA and LDMC to present higher survival. For a set of eight native cloud forest species, a total of 2,202 seedlings were planted in four pastures, five secondary forests and three forests subjected to traditional selective logging, in TMCF landscapes in Eastern Mexico. Seedling survival was high after 3 years: 62% in pastures, 80% in secondary forests and 88% in logged forests. Growth rates were lowest in pastures, followed by secondary forests and highest in logged forests. LMA was a strong predictor of seedling survival in all of the environments; tree species with higher LMA presented greater survival. LDMC was related to seedling survival in the three environments, although to a lesser extent than LMA. In the pastures, higher LMA and LDMC were linked to lower growth. Synthesis and applications. This study supports the potential of shade tolerant tree species in restoration efforts to assist the recovery of this important functional group and to accelerate succession across altered environments. Our results support the notion that conservative leaf functional traits are linked to a higher probability of survival, not only in the shaded understorey, but also under high solar radiation in transformed habitats. Leaf mass area (LMA) in particular is a reliable predictor of seedling survival for shade tolerant species. Species selection based on LMA could thus improve restoration initiative outcomes: tree species with high LMA present higher survival probability and can be introduced into pastures, secondary forests and selectively logged forests.

Spatial and temporal scales of canopy disturbance and recovery across an old‐growth tropical rain forest landscape

Article

Full-text available

Dec 2021
ECOL MONOGR

The distribution of canopy heights in tropical rain forests directly affects carbon storage and the maintenance of biodiversity. We report results from a unique 20‐yr record of annual monitoring of canopy‐height distributions across an old‐growth tropical rain forest landscape at the La Selva Biological Station in Costa Rica. Canopy heights to 15 m were measured annually in 18 0.50‐ha plots at 231 points on a 5 × 5 m grid from 1999–2018 (nine plots in 1999), and heights >15 m were classified as “high canopy.” During the study two major disturbance events (one immediately prior to the study) dominated the landscape‐scale distribution of canopy heights. Height recovery from the 1997–1998 strong El Niño disturbance took approximately 15 yr. Frequency of canopy gaps varied an order of magnitude among years and 96% disappeared in ≤2 yr. High‐canopy coverage and gap frequency varied substantially across the local gradients of soil nutrients and topography, and plot‐level conditions and trends frequently differed from the landscape‐level patterns. In contrast to the two major landscape‐level disturbances, significant plot‐level disturbances were common throughout two decades. Including a similar data set taken in 1992, canopy‐height distributions for the last three decades over this old‐growth tropical rain forest landscape are most parsimoniously interpreted as showing local disturbance and recovery and no unidirectional trends over time. Together these results suggest that understanding the landscape‐ and plot‐level dynamics of tropical rain forest canopy‐height distributions will require repeat sampling for multiple decades, while accurately measuring gap frequency and recovery will require sample intervals of ≤2 yr.

Tropical-temperate dichotomy falls apart in the Asian Palmate Group of Araliaceae

Preprint

Full-text available

Oct 2021

PREMISE The use of climatic data on phylogenetic studies has greatly increased in the last decades. High-quality spatial data and accurate climatic information are essential to minimize errors in the climatic reconstructions to the past. However, despite the huge amount of already available biodiversity digital information, the process of compiling, cleaning, and comparing spatial data from different open data sources is a time-consuming task that sometimes ends up with low-quality geographical information. For this reason, researchers often resort qualitative approximations among which World bioclimatic classification systems or the experts’ criteria are the most used. Our aim is to evaluate the climatic characterization of the genera of the Asian Palmate Group (AsPG) of the ginseng family (Araliaceae), one of the classical examples of tropical-temperate plant families. METHODS We compiled a curated worldwide spatial database of the AsPG genera. We then created five raster layers representing bioclimatic regionalizations of the World. Finally, we crossed the database with the layers to characterize the AsPG genera. RESULTS We found large disagreement in the climatic characterization of genera among regionalizations and little support for the tropical-temperate dichotomy. Both results are attributed to the complexity of delimiting tropical, subtropical and temperate climates in the World and to the distribution of the study group in regions with transitional climatic conditions. CONCLUSIONS The complexity in the climatic classification of this classical example tropical-temperate dichotomy, calls for a general revision in other families. In fact, we claim that to properly evaluate tropical-temperate transitions we cannot ignore the complexity of distribution ranges.

Área foliar y densidad básica en ramas de especies arbóreas en gradientes altitudinales de un bosque húmedo tropical en Huánuco

Thesis

Full-text available

Jan 2018

Humberto Zelada Gárate

Thesis that deals with the measurement of three functional traits in different tree species located in an altitude gradient of the Peruvian Central Forest in a context of climate change ...

SISTEMA DE PLANTIO ADENSADO PARA A REVEGETAÇÃO DE ÁREAS DEGRADADAS DA MATA ATLÂNTICA: BASES ECOLÓGICAS E COMPARAÇÕES DE CUSTO/BENEFÍC1O COM O SISTEMA TRADICIONAL

Article

Full-text available

Jan 2024

Fast growing of weed species, like Panicum maximum inhibits forest species development in rehabilitation of degradaded areas and proporcionales fire occurrence during dry season. Adensed plantation system utilizes ecologycal conccepts based on successional processes in tropical forests, utilizing high species diversity and trying to mantatn adequated proportion between pioneer, secondary and climax species. Like late stages of successional processes on tropical forest, adensed plantation uses zoochorichous species in major proportion than other dispersal systems. Plantation is realized on adensed way with 1 m2/plant, and a line of pioneer species followed by a line of pioneer intercalated with non-pioneer. At this way, each non-pionner is surrounded by four pioneer, wich proporcionate shade for its development. Preliminary results demonstrated high survival in the adensed system, comparated with traditional one (1 plant/4 m²) and reduction of fire occurrence. Adensed plantation promoted fast covering of soil surface, reducing the necessity of mantainance. Although inicial costs of adensed plantation were higher than traditional, final costs are reduced because of the minor number of maintenance services. Key words: Adensed plantation; Tropical forest.

Composition and Association of Vegetation with Medicinal Plant Pikajar (Schizaeadigitata) in Meratus Mountain, South Kalimantan, Indonesia

Article

Jan 2019

The Meratus Mountains save a wealth of biodiversity that functions as a medicinal plant. One of the medicinal plants is pikajar (Schizaeadigitata). This plant species is effective for maintaining stamina, treating back pain and being able to overcome impotence. But this plant species in natural forests has begun to decrease its potential and regeneration still relies on natural regeneration. As a forest community, of course the existence of other species is very dependent on other species, as well as pikajar, so it is important to conduct research on the association between vegetation around the pikajar with pikajar itself, because in cultivation always pay attention to the associated plant communities with plants that become objects of preservation so that these plants can grow well. This study aims to analyse the composition and structure of vegetation and the dominant species that have an association relationship with pikajar so that later can be used as consideration for conservation in an exact manner. The results of the study found that there were about 50 species of vegetation in the community unit, 38 species of seedlings, 31 species of sapling, 15 species of poles and 10 species of trees. The association of pikajar with 5 dominant species that have a very strong relationship is mahang (Macarangajavanica) for seedling and sapling levels, while at the pole level and tree the strong association occurs with the rubber (Heveabrasiliensis).

Gap geometry, seasonality and associated losses of biomass – combining UAV imagery and field data from a Central Amazon forest

Article

Full-text available

Jan 2023
BGD

Understanding mechanisms of tree mortality and geometric patterns of canopy gaps is relevant for robust estimates of carbon stocks and balance in tropical forests, and for assessing how they are responding to climate change. We combined monthly RGB images acquired from an unmanned aerial vehicle with field surveys to identify gaps in an 18-ha permanent plot in an old-growth Central Amazon forest over a period of 28 months. In addition to detecting, we measured the size and shape of gaps, and analyzed their temporal variation and correlation with rainfall. We further described associated modes of tree mortality or branch fall and quantified associated losses of biomass. Overall, the sensitivity of gap detection differed between field surveys and imagery data. In total, we detected 32 gaps either in the images and field, ranging in area from 9 m2 to 835 m2. Relatively small gaps (< 39 m2) associated with branch fall were the most frequent (11 gaps). Out of 18 gaps for which both field and imagery data were available, three could not be detected remotely. This result shows that a considerable fraction of tree mortality and branch-fall events (~ 17 %) affect only the lower canopy and the understory of the forest and thus, are likely neglected by assessments of top of the canopy. Regardless the detection method, the size distribution of gaps in our study region was better captured by a Weibull function. As confirmed by our detailed field surveys, we believe that this pattern was not biased by gaps possibly undetected from image data. Although not related to differences in gap size, the main modes of tree mortality partially explained associated losses of biomass. The rate of gap area formation expressed as the percent per month was positively correlated with the frequency of extreme rainfall events, which may be related to a higher frequency of storms propagating destructive wind gusts. Our results demonstrate the importance of combining field observations with remote sensing methods for monitoring gap dynamics in dense forests. The correlation between modes of tree mortality and gap geometry with associated losses of biomass provide evidence on the importance of small-scale events of tree mortality and branch fall as processes that contribute to landscape patterns of carbon balance and species diversity in Amazon forests. Regional assessments of the dynamics and geometry of canopy gaps formed from branch fall and individual tree-mortality (e.g., from few to hundreds of m2) up to catastrophic blowdowns associated with extreme rain and wind (e.g., from hundreds of m2 to thousands of ha) can reduce the uncertainty of landscape assessments of carbon balance, especially as the frequency and intensity of storms causing these events is likely to change with future Amazon climate.

Photosynthesis adaption in Korean pine to gap size and position within Populus davidiana forests in Xiaoxing’anling, China

Article

Feb 2022

Forest gaps restrict the restoration of temperate secondary forest to broad-leaved Korean pine forest in zonal climax vegetation by affecting the growth of Korean pine (Pinus koraiensis). However, the photosynthetic adaptability of Korean pine to gap size and position within the gap is unclear. In order to explore the adaptability of young Korean pine (35 years) to different gap sizes in Xiaoxing’anling, photosynthetic capacity and microenvironmental factors (leaf temperature, light transmittance) of Korean pine needles in three positions in the gap (central, transition, and edge areas) were investigated. Three gaps were identified in the secondary Populus davidiana forest: a large 201 m2 gap, a middle 112 m2 gap, and a small 50 m2 gap; 12 m2 of the understory was sampled as a control. The results show that: (1) maximum net photosynthetic rate (Pmax) in needles of Korean pine growing in the large gap was higher than in the small gap, and Pmax in the centre in the same gap was higher than in the transition and edge areas; (2) light saturation point (LSP) and photosynthetic quantum yield (AQY) of needles in the large gap were higher than in the small gap, while the light compensation point (LCP) and chlorophyll contents of needles were lower in the small gap; and, (3) Pmax had a significant positive correlation with temperature and light transmittance. It is suggested that the larger the gap in secondary Populus davidiana forests, the greater the change in light intensity and temperatures, the stronger the light adaption of Korean pine needles and the higher the photosynthetic capacity. Therefore, in the recovery of broad-leaved/Korean pine forests, suitable gaps should be created and gap microhabitats fully utilized to accelerate the restoration process.

Long-Term Hydrological Research in the Humid Tropics

Chapter

Jan 2022

Ian Douglas

Long seen as stable ecosystems, tropical rainforests are vulnerable to natural disturbances and susceptible to human activities. Forest hydrology has extensively examined how forest management affects hydrological processes and is now assessing the impacts of increasing forest modification and global heating. The dominant way of studying this was the paired catchment approach, first used in Europe in 1867. It involves automatic comparison of hydrological responses from differing land cover states through varying weather conditions over the same time periods and includes all catchment processes. Ideally such studies should be long-term in order to cope with the significance of extreme rainfalls, droughts, tropical cyclones, and earth movements for the timing and magnitude of water, solute and sediment fluxes. Examples of successful research in tropical rainforest hydrology include that at the Barro Colorado site in Panama, the Luquillo Experimental Forest in Puerto Rico, La Selva in Costa Rica, and the Babinda catchments in Australia. In. South-East Asia, the Sg. Tekam and Bukit Tarek studies in Peninsular Malaysia, the Cikumutuk project in Indonesia, and the Pham Kung watershed investigations in Thailand have tested significant hypotheses and provided key data. While many questions about evaporation, runoff generation and sediment yield are now well understood, there is a great need for long-term research incorporating all aspects of the El Niño – La Nina (ENSO) cycle and the rare extreme events that can dominate sediment yields and cause tree falls and landslides.

Tropical Rainforest Gaps And Tree Species Diversity

Abstract

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