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Short-rotation forest plantations with hybrid aspen on abandoned agricultural land are a novel use of land in eastern and northern Europe; however, to date, their impact on floristic diversity has not been thoroughly studied. Our aim is to determine the kind of vascular plant and bryophyte (including epiphytes) species that benefit from such planta...
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The flora and vegetation of river valleys are currently greatly transformed as a result of the increased influence of many factors related to human activity. Earlier research on the vegetation of the Rzeszow Reservoir was carried out in 1994-95. Since then, its depth has been greatly diminished and its surface area decreased two-fold. Moreover, typ...
Citations
... Among the suitable tree species for intensive biomass production [6], hybrid aspen (Populus tremula L. × P. tremuloides Michx.) has shown a potential to be more productive than native tree species of Northern Europe [10,11]. Hybrid aspen can produce more than 20-25 m 3 ha − 1 yr − 1 of stemwood at the end of the first 25-year rotation cycle for industrial woody biomass and renewable energy in short-rotation forestry systems [11][12][13][14], and at the same time preserve soil carbon pools [15] and increase biodiversity [16,17] in comparison with agricultural land-use. ...
Background
Afforestation of non-forestland is a new measure by the European Union to enhance climate mitigation and biodiversity. Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) is among the suitable tree species for afforestation to produce woody biomass. However, the best performing genotypic material for intensive biomass production and its physiological adaptation capacity is still unclear. We compared 22 hybrid aspen genotypes growth and leaf physiological characteristics (stomatal conductance, net photosynthesis, intrinsic water-use efficiency) according to their geographical north- or southward transfer (European P. tremula parent from 51° to 60° N and North American P. tremuloides parent from 45° to 54° N) to hemiboreal Estonia (58° N) in a completely randomized design progeny trial. We tested whether the growth ranking of genotypes of different geographical origin has changed from young (3-year-old) to mid-rotation age (13-year-old). The gas exchange parameters were measured in excised shoots in 2021 summer, which was characterised with warmer (+ 4 °C) and drier (17% precipitation from normal) June and July than the long-term average.
Results
We found that the northward transfer of hybrid aspen genotypes resulted in a significant gain in growth (two-fold greater diameter at breast height) in comparison with the southward transfer. The early selection of genotypes was generally in good accordance with the middle-aged genotype ranking, while some of the northward transferred genotypes showed improved growth at the middle-age period in comparison with their ranking during the early phase. The genotypes of southward transfer demonstrated higher stomatal conductance, which resulted in higher net photosynthesis, and lower intrinsic water-use efficiency (iWUE) compared with northward transfer genotypes. However, higher photosynthesis did not translate into higher growth rate. The higher physiological activity of southern transferred genotypes was likely related to a better water supply of smaller and consequently more shaded trees under drought. Leaf nitrogen concentration did not have any significant relation with tree growth.
Conclusions
We conclude that the final selection of hybrid aspen genotypes for commercial use should be done in 10–15 years after planting. Physiological traits acquired during periods of droughty conditions may not fully capture the growth potential. Nonetheless, we advocate for a broader integration of physiological measurements alongside traditional traits (such as height and diameter) in genotype field testing to facilitate the selection of climate-adapted planting material for resilient forests.
... Another factor that impacts understory is stand age. In new forests on previous agricultural land rapid changes occur as young stands mature and the canopy closure brings along a shift from light-demanding to shade-tolerant species (Archaux et al. 2010;Tullus et al. 2015). ...
New forests on former agricultural land originate either from natural regeneration or active restoration. Previous research has compared biodiversity of naturally regenerated stands (NR) and plantations (PL), however, whether understory succession towards natural forests depends on stand type remains unknown. In this study, we used data from two monitorings on permanent plots (2011 and 2019) in PL (n = 11) and NR (n = 11) birch stands in Estonia to highlight successional changes in herb and bryophyte communities together with environmental changes. We further evaluated whether stand type influenced the recovery of forest specialists. We found an increase in tree growth characteristics, soil phosphorus and nitrogen content, no change in light conditions and a decrease in soil pH in both stand types. The amount of litter and deadwood was higher in NR in 2011. Herb richness increased from 123 to 130 and the number of bryophytes from 43 to 62. Stand types shared 50% of herb species in 2011 and 2019, while the fraction of shared bryophytes increased from 37.2 to 56.5%. We observed an increase of forest specialists and a decrease in light-demanding species (based on indicator value for light) in both stand types. Bryophyte cover and richness increased and species compositions of stand types converged. However, the number of bryophytes was significantly higher in NR plots indicating the significance of deadwood as growth substrate. We conclude that the recovery of forest understory followed similar successional pathways in PL and NR.
... Therefore, it has been argued that such plantations are "green deserts" that host low biodiversity (Horák et al., 2019;DellaSala, 2020). Contradicting this view, a number of studies have found that hybrid aspen plantations on previously agricultural land have great potential to host vascular plant, bryophyte, and lichen species early in their development due to their rapid growth but sparse canopy (Tullus et al., 2015;Randlane et al., 2017), particularly if plantations are located in the vicinity of forests as possible sources of colonization (Randlane et al., 2017). However, the diversity and communities of soil fungal organisms, which are important drivers of forest health, biomass productivity (Van der Heijden et al., 2008), and nutrient cycling (Treseder and Lennon, 2015;Bahram et al., 2020), are poorly known for former agricultural lands afforested with hybrid aspen short-rotation coppice. ...
... Before the establishment of hybrid aspen plantations, previous land use was as cropland (N = 9) or grassland (N = 11) (Lutter et al., 2016b). Hybrid aspen sites were located 35-670 m from the nearest forest edge (Tullus et al., 2015). On 13 sites, agricultural land use had ceased more than 1 year before afforestation, and on seven sites, afforestation was performed immediately after field abandonment. ...
... However, present knowledge about the biodiversity and succession in hybrid aspen plantations mainly covers vascular plant, bryophyte, and lichen species (Tullus et al., 2015;Randlane et al., 2017), whereas soil fungal communities are poorly studied. To our knowledge, there are no studies on the diversity and composition of soil fungal biota in hybrid aspen plantations planted on previously agricultural lands and comparison of these fungal communities to those of native European aspen forests. ...
Background
The cultivation of short-rotation tree species on non-forest land is increasing due to the growing demand for woody biomass for the future bioeconomy and to mitigate climate change impacts. However, forest plantations are often seen as a trade-off between climate benefits and low biodiversity. The diversity and composition of soil fungal biota in plantations of hybrid aspen, one of the most planted tree species for short-rotation forestry in Northern Europe, are poorly studied.
Methods
The goal of this study was to obtain baseline knowledge about the soil fungal biota and the edaphic, floristic and management factors that drive fungal richness and communities in 18-year-old hybrid aspen plantations on former agricultural soils and compare the fungal biota with those of European aspen stands on native forest land in a 130-year chronosequence. Sites were categorized as hybrid aspen (17–18-year-old plantations) and native aspen stands of three age classes (8–29, 30–55, and 65-131-year-old stands). High-throughput sequencing was applied to soil samples to investigate fungal diversity and assemblages.
Results
Native aspen forests showed a higher ectomycorrhizal (EcM) fungal OTU richness than plantations, regardless of forest age. Short-distance type EcM genera dominated in both plantations and forests. The richness of saprotrophic fungi was similar between native forest and plantation sites and was highest in the middle-aged class (30–55-year-old stands) in the native aspen stands. The fungal communities of native forests and plantations were significantly different. Community composition varied more, and the natural forest sites were more diverse than the relatively homogeneous plantations. Soil pH was the best explanatory variable to describe soil fungal communities in hybrid aspen stands. Soil fungal community composition did not show any clear patterns between the age classes of native aspen stands.
Conclusion
We conclude that edaphic factors are more important in describing fungal communities in both native aspen forest sites and hybrid aspen plantation sites than forest thinning, age, or former land use for plantations. Although first-generation hybrid aspen plantations and native forests are similar in overall fungal diversity, their taxonomic and functional composition is strikingly different. Therefore, hybrid aspen plantations can be used to reduce felling pressure on native forests; however, our knowledge is still insufficient to conclude that plantations could replace native aspen forests from the soil biodiversity perspective.
... bryophyte species only in spruce plantations. The low richness of bryophyte species in hybrid poplar plantations could be explained by their inability to grow in the presence of broadleaf litter (Jean et al., 2017;Bartels et al., 2018) due to bryophytes specializing on the acidic and low-light conditions below coniferous canopies (Barbier et al., 2008;Tullus et al., 2015). Recalcitrant needleleaf litter associated with low decomposition rates in spruce plantations (Chomel et al., 2015) had probably produced favorable conditions for bryophytes. ...
Although monocultures are important for timber production, they are often associated with lower biological diversity than mixtures. Thus, mixed plantations have been suggested as a way to enhance biodiversity because of their inherent compositional diversity. However, the effects of monocultures versus mixtures on understory diversity and composition can vary in different ecosystems. The objective of this study was to assess how monocultures and mixed plantations influence understory vegetation diversity and composition in the boreal forest region of southern Quebec. We sampled plantations established with deciduous Populus trichocarpa Torrey & A. Gray × balsamifera L. and P. maximowiczii Henry × balsamifera L. and coniferous Picea abies (L.) Karst. and Picea glauca (Moench) species planted in monocultures and in mixed plantations on abandoned farmlands and a forest site. We assessed understory vegetation diversity and composition in each canopy type (coniferous, deciduous , mixed) and in each plantation type. We evaluated bryophyte and lichen diversity and composition specifically in tree microhabitats: soil, tree bases, and tree trunks. We found that vascular plant and lichen species richness was similar in all plantation types, while bryophyte species richness was higher in spruce monocultures and in mixed plantations compared to poplar monocultures. Our results also highlight how land-use history influenced vascular plant composition as abandoned farmland sites were composed of more ruderal vascular plants, while the previously forested site was composed of species found in natural forests. In the context of reforestation and plantations, our study suggests mixing spruce with poplars to maximize understory vegetation diversity as the addition of spruce in mixed plantations promoted the establishment of terrestrial bryophytes, while poplars favored the establishment of epiphytic lichens.
... Similar to the second and third groups, the fifth group of authors also discussed the relationships between farmland abandonment and vegetation and species diversity but paying more attention to the afforestation on abandoned farmland in eastern and northern Europe. For example, hybrid aspen plantations planted on abandoned farmland in Estonia were monitored, and their impacts on understory vegetation and species numbers were discussed [105], as well as the effect of alder on soil nitrogen [106]. In another study, the aboveground biomass, belowground biomass, and nutrients of natural birch forests on abandoned farmland in Estonia were studied [107]. ...
Farmland abandonment is one of the most important land use changes in the world today and crucial to the sustainable development of the global environment. The authors carried out extensive research on farmland abandonment from many perspectives, but, due to the variety of the research contents, rich research perspectives, and complex research objects, the current research in this field lacks comprehensiveness, objectivity, and systematization. In this study, the bibliometric R software packages bibliometrix and biblioshiny (K-Synth Srl, Naples, Italy) were used to analyze the development history and current situation of 896 articles on farmland abandonment in the Web of Science core collection database from 1980 to 2021, revealing their research hotspots and predicting the future development trends. Over the past 40 years, the number of published papers on abandoned farmland has continuously increased. Research mainly focused on the ecological environment, with natural succession, biodiversity, and vegetation restoration being high-frequency keywords in this field. Research on the social aspects of farmland abandonment has developed rapidly in the past 6 years. Based on these findings, this paper put forward four future research directions: the data source for the extraction of abandoned farmland should transform to high spatial-temporal resolution and hyperspectral remote sensing images; the method should pay more attention to the time series change detection and the application of the model; future research should focus on the economic costs of the reclamation of abandoned farmland and the ecological consequences of such reclamation; and the global ecological impact of vegetation succession after the abandonment of farmland should be further discussed from a broader perspective.
... Poplar in plantations is harvested between 18-25 years for timber production and between 15-18 years for chip-wood and paper manufacture (Rédei 2010). The earliest orchids appear aboveground is (4-) 7-8 years (Archaux et al. 2010, Tullus et al. 2015, Molnár V. et al. 2022. Young poplars are sensitive to understory growth, which significantly retards their growth and productivity (Heilman 1999). ...
Poplar monocultures are some of the most common short-rotation coppices. While they are most often considered of low environmental value, they have recently gained recognition for their multifaceted role in ecological engineering, such as carbon sinks, soil remediators or green energy producers. Nonetheless, the biodiversity of poplar plantations remains little known and largely overlooked. Here we conducted a systematic botanical survey of 232 poplar plantations within the Pannonian ecoregion (central Europe) in order to assess their plant diversity , with particular focus on terrestrial orchids. Our results highlight that almost 60% of poplar monocultures harbour terrestrial orchids, some with several thousand specimens. Overall, we documented the occurrence of 15 species of terrestrial orchids in the surveyed plantations, including taxa with limited distributions and a threatened conservation status. For instance, we report numerous new populations of Epipactis bugacenis and E. tallosii in poplar plantations, suggesting that the majority of these taxa occur in poplar monocultures within Hungary. We analysed and highlight soil chemistry and plantation characteristics that predict the occurrence and species richness of terrestrial orchids in poplar monocultures. The probability of orchids being present is highest in older and larger poplar plantations, characterized by high total organic matter content and high soil pH. We conclude that plantations of native and alien poplar harbour valuable plant communities, including terrestrial orchids and other vascular plants of significant conservation importance. Using the knowledge generated here, we recommend delaying or partial harvest of poplar plantations to increase their conservation potential.
... Cemeteries may also play a signifi cant role in the conservation of orchids in Turkey (Löki et al. 2015(Löki et al. , 2019aMolnár et al. 2017a, b). Another type of anthropogenic habitats, poplar plantations harbor at least 31 orchid species in 15 European countries (Werner 1982, Adamowski and Conti 1991, Molnár et al. 1998, 2000Adamowski 2006, Csiky 2006, Jakubska et al. 2006, Tóth 2009, Archaux et al. 2010, Voigt and Somay 2013, Csábi et al. 2015, Tullus et al. 2015, Aradi et al. 2017, Illyés et al. 2017, Lukács et al. 2017, 2020Molnár et al. 2022). ...
Törökország orchideaflórájára jellemző, hogy egyrészt az egyik leggazdagabb a Mediterrán térségben, másrészt a mezőgazdaság intenzívebbé válása, a tájhasználat megváltozása, az élőhelyek átalakulása, a túllegeltetés és a gumók kiásásával járó szálep-gyűjtés miatt rendkívül veszélyeztetett. Közleményünkben szeretnénk felhívni a figyelmet a gazdasági célú nyárfaültetvényekre mint orchidea-élőhelyekre. 5 tartomány 8 tanulmányozott ültetvénye közül 6-ban fordultak elő orchideák, összesen 7 nemzetség 12 faját (Anacamptis elegans, A. fragrans, A. pyramidalis, Cephalanthera longifolia, C. damasonium, Epipactis helleborine, E. persica, Himantoglossum jankae, Ophrys apifera, O. oestrifera, Ophrys sp., Serapias feldwegiana) találtunk meg. Az átlagosan mindössze 0,27±0,21 hektár területű ültetvényekben 0–5 faj (átlag±szórás=1,88±1,80) jelenlétét regisztráltuk. Az orchideaállományok sűrűsége 0 és 355,6 példány/hektár között változott (átlag±szórás=88,95±124,6). Az ültetvényekben egyaránt előfordultak gumós és rizómás növekedési típusú orchideák, de többségben voltak az előbbiek: a megtalált orchideafajok közül 8 (67%), az egyedek közül 232 (94%) volt gumós. Az orchideás ültetvényekben az átlagos törzsátmérő 16,7 és 21,8 cm közötti volt. A tanulmányozott ültetvényekben nem tapasztaltuk orchideagumók gyűjtésének vagy túllegeltetésnek nyomait, ami hozzájárulhat ahhoz, hogy megfelelő élőhelyül szolgáljanak egyes orchideafajok számára. Figyelembe véve a nyárfaültetvények jelentős kiterjedését és területük várható további növekedését Törökországban, szerepüket az orchideák megőrzésében érdemesnek tűnik vizsgálni.
... Based on the model estimations, the fitted probabilities were predicted with 95% confidence intervals for all studied factors. Data on tree growth, environmental and soil-related factors were obtained from previous studies of our working group (Tullus et al. 2015;Lutter et al. 2016aLutter et al. , b, 2017. The Shapiro-Wilk test was used to test the normality of the variables. ...
Entoleuca mammata [causing Hypoxylon canker (HC)] is one of the most serious pathogens that are colonising Populus species. The area of fast-growing hybrid aspen plantations has remarkably increased in northern Europe because of the high demand for woody biomass, but the prevalence of HC and the stand-related and environmental factors that favour its presence have rarely been monitored in such monocultural plantations. The presence of E. mammata in Estonia was proven by ITS sequence on hybrid aspen. Repeated monitoring after 4 years in 24 hybrid aspen plantations found that the share of visually damaged trees by HC increased from 0.6% (15-year-old trees) to 1.6% (19-year-old trees). The mortality rate of the infected trees during the 4 years was 100%. The probability of HC incidence was favoured by tree vigour and higher soil acidity. The higher susceptibility of more vigorous trees might be related to their trade-off between productivity and defence compounds. The share of trees with clear visual symptoms of HC can be considered marginal, but the aggressive nature of the pathogen suggests the need to extend the monitoring period, especially in recently thinned sites, and to expand the observations to native Populus tremula stands.
... Also other studies have shown that the first colonizers after disturbance are typically colonists and shortlived shuttle species, but over a longer period the colonists will be overgrown by more competitive perennials (During et al., 1987;van Tooren and During, 1988;Jonsson, 1998;Jonsson and Esseen, 1998;Heinken and Zippel 2004). The dispersal of forest species by air takes time and the increase in species richness starts much later, somewhere in stands at least ten years old, as shown in the comparative study of hybrid aspen plantations, at this stage bryophyte species start to colonize also the tree trunks (Tullus et al., 2015). In Norwegian boreal forests the vegetation change turned in the direction of predisturbance state three years after disturbance, but it was suggested to take 5-25 more years to be completed (Rydgren et al., 2004). ...
The abandonment of agricultural areas is usually accompanied by the stochastic encroachment of shrubs and trees or deliberate afforestation, but this leads as a rule to the decline of grassland plant diversity. Future climate change may increase precipitation and air humidity in temperate and boreal forest zones, and thus change vegetation dynamics. We conducted a five-year experiment on the Free Air Humidity Manipulation experimental facility (FAHM) with planted deciduous trees to examine how both the grassland afforestation with deciduous trees and the increase of air humidity in interaction with forest soil supplementation and cover of herbaceous layer affect the species richness, composition and cover of bryophyte layer. The effects of the same factors on the cover of herbaceous layer were also analysed. The species of bryophytes and cover of herbaceous and bryophyte layer were surveyed in September of 2007-2011. During these early years of forest succession, herbaceous layer cover decreased and bryophyte cover increased , although the direct suppressing effect of tree canopy was observed on both layers. The input of forest soil as diaspore deposit of bryophytes had some positive effect on the cover of bryophytes, while the increased air humidity had quite limited effect. The density of tree canopy (defined in our study through Leaf Area Index) first promoted the species richness of bryophytes, particularly of species with grassland preference. However, together with the herbaceous layer it became suppressing in the last year. The species richness of bryophytes declined during the first years and then stabilised. The decline relied mainly on the disappearance of grassland species. The richness of bryophytes was supported by forest soil supplementation only in the initial year. The bryophyte species composition changed rapidly in first two years mainly due to decline of short-lived grassland species and perennial species started to dominate. Our results show that bryophyte succession during the afforestation is largely driven by natural loss of grassland specialists after tree canopy closure, while diaspore supplementation from forest and improved air moisture level had small effects.
... So far, the impact of hybrid aspen plantations on the understory diversity on former mining areas has only briefly been studied in young stands [10], but the understory vegetation in older stands needs to be investigated as well. A study by Tullus et al. [36] of midterm-aged hybrid aspen plantations in former agricultural sites showed that hybrid aspen plantations host a rich understory flora where species with different ecological requirements are present, ranging from typical fallow species to shade-tolerant forest species. Studies of coal mine reclamation in the USA suggest that the species of herbaceous cover may be an important factor in forest establishment through both direct and indirect effects, and that the high diversity of ground cover may be beneficial for ecosystem development [37]. ...
... Altogether 96 vascular plant species and 27 bryophyte species were found in the three plantation types, which is considerably more than the respective figures of 75 and 12 recorded at a young age. The overall species richness of vascular plants and bryophytes had increased in all plantation types, following a similar trend to that observed in midterm hybrid aspen plantations on former agricultural land [36]. While no bryophyte species were found on tree trunks or tree bases in young plantations, the bryoflora of midterm plantations contained epiphytic species as well. ...
The development of forest ecosystem components (tree layer, understory vegetation and topsoil) in a reclaimed oil shale quarry was evaluated based on the repeated monitoring of sample plots 5 and 15 years after afforestation with hybrid aspen. Trees had been planted directly on levelled quarry spoil (site group A1) or on quarry spoil with restored topsoil (site group A2). The reference group included hybrid aspen plantations on former arable land (site group B1). Over a decade, the relative tree growth had been slower on A1 and A2, compared to B1. Soil reaction (pHKCl) had decreased and soil total nitrogen (Ntot) had increased on A1. High pHKCl value and low stocks of Ntot, phosphorus (P), manganese (Mn) and boron (B)
restricted tree growth on A1. The properties of soil, as well as understory vegetation on A2 were similar to those on B1, which indicates that restored topsoil ensured the faster development of A2 towards the Hepatica forest type.
