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Jiaojun Zhu - One of the best experts on this subject based on the ideXlab platform.
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regeneration and succession a 50 year gap dynamic in temperate Secondary Forests northeast china
Forest Ecology and Management, 2021Co-Authors: Jiaojun Zhu, Chunyu Zhu, Geoff G Wang, Xiao Zheng, Jiansheng Cao, Jinxin ZhangAbstract:Abstract Forest gaps are essential small-scale disturbances in forest succession. However, little attention has been paid to the long-term effects of gap dynamics on woody species regeneration and succession. We selected 20 medium and 25 large gaps representing a range of age classes (0–10, 10–20, 20–30, 30–40, and 40–50 years) from remote-sensing images obtained in 1964, 1976, 1986, 1993, 2003, and 2014 to examine long-term gap regeneration processes in a Secondary forest in Northeast China. We conducted field surveys to determine the regeneration status, density index (DI), and richness index (RI) of selected gaps. The importance value (IV) of each woody species was calculated, and all species were classified by shade tolerance. The results showed that in gaps of 0–10 years, the DI and RI were mainly dominated by shade-intolerant species in large gaps and intermediate species in medium gaps. When gap age increased to 10–20 years, the greatest RI was observed in large gaps due to an increase in intermediate species, and the dominant species (IV > 0.1) changed from shrubs to trees (Acer mono). The DI and RI decreased over time in medium gaps, but A. mono remained the dominant species in these gaps. By 20–30 years after gap formation, large gaps showed decreased DI and RI, associated with the exclusion of shade-intolerant and intermediate species, and Tilia amurensis joined the dominant species class. In medium gaps, a decrease in DI was associated with self-thinning among intermediate shade-tolerant species. Once gap age exceeded 30 years, the DI, RI, and dominant species became stable in both large and medium gaps. Our findings indicated that natural gaps can improve the regeneration of late-successional species in Secondary Forests, especially at the first 30 years. However, there was a barrier in succession of the Secondary Forests to climax Forests relying on natural gap regeneration due to the absence of key species such as Korean pine (Pinus koraiensis Sieb. et Zucc.). These results can provide a significant reference for close-to-nature management of temperate Secondary Forests in practice.
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restoring temperate Secondary Forests by promoting sprout regeneration effects of gap size and within gap position on the photosynthesis and growth of stump sprouts with contrasting shade tolerance
Forest Ecology and Management, 2018Co-Authors: Ting Zhang, Qiaoling Yan, Jing Wang, Jiaojun ZhuAbstract:Abstract To improve the productivity and ecological functions, it is essential to recover Secondary Forests, the major forest resources in the world, by promoting the regeneration of dominant tree species. Forest gaps are a dominant form of small-scale disturbances in Secondary Forests, and sprout regeneration commonly occur after the gap formation from logging. Within-gap position and gap size are two key characteristics affecting tree regeneration by changing micro-environments. Promoting the sprout regeneration of dominant tree species under forest gaps with various sizes and within-gap positions is a key measure to recover Secondary Forests. Twelve artificial gaps were created in March 2015 and the photosynthesis and growth of stump sprouts of three dominant tree species with varying levels of shade tolerance (Quercus mongolica, Acer mono, and Tilia mandshurica) were monitored in 2016. The results showed that within-gap position and gap size had significant effects on the photosynthetic ability of stump sprouts of Q. mongolica, i.e., the moderate light condition at the center parts of large gaps was more beneficial to its photosynthesis with the maximum PNmax of 26.49 μmol m-2 s-1. Gap size significantly affected the biomass of stump sprouts of both Q. mongolica (shade intolerant tree species) and A. mono (intermediate shade tolerant tree species), e.g., the aboveground biomass of these two tree species in large gaps (178.90 g for Q. mongolica and 158.42 g for A. mono, respectively) were significantly higher than those in small gaps (50.52 g for Q. mongolica and 56.95 g for A. mono, respectively) (P
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impacts of conversion from Secondary Forests to larch plantations on the structure and function of microbial communities
Applied Soil Ecology, 2017Co-Authors: Weiwei Zhang, Kai Yang, Jiaojun ZhuAbstract:Abstract In response to increasing timber demands, extensive areas of Secondary Forests have been converted to larch (Larix gmelinii) plantations in northeast China. It has been reported that the conversions have led to reduction in soil organic matter and nutrient availability. Soil microbes play crucial roles in nutrient cycling. However, the effects of forest conversion on soil microbes are not yet well understood in temperate forest ecosystems. In this study, the structure and function of bacterial and fungal communities were compared between larch plantations and adjacent Secondary Forests relative to surface litter and two soil layers (0–10 cm and 10–20 cm) using Illumina MiSeq sequencing. We found that the impacts of the forest conversion on soil microbes mainly occurred in the top (0–10 cm) soil layer. Soils in Secondary Forests were associated with a higher proportion of copiotrophic bacteria (Proteobacteria and Actinobacteria). In contrast, larch plantation soil was enriched with Acidobacteria, which are oligotrophs that appear to be well suited to acidic conditions. These differences in soil bacterial communities confirm that the forest conversion resulted in soil acidification and a large decline in available soil nutrient in larch plantations. Furthermore, the results of bacterial functional genes, inferred by PICRUSt, and the results of extracellular enzyme assays indicate that fungi likely dominated soil organic carbon decomposition in forest soils. Sordariomycetes was the most abundant fungal class in soils of Secondary Forests. The abundance of Sordariomycetes fungi was related to higher levels of almost all enzymes measured, except for cellobiohydrolase and β-1,4-N-acetyl-glucosamidase. These two enzymes were positively associated with Agaricomycetes fungi in soils of Secondary Forests. The fungal community in the soils of larch plantations was dominated by the class Agaricomycetes, which was positively associated with activities of both hydrolytic and oxidative enzymes. These results indicate that fungal classes, Sordariomycetes and Agaricomycetes, are most likely responsible for the decomposition of soil organic matter in Secondary Forests, while Agaricomycetes fungi might be more important in controlling decomposition in larch plantations.
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seed regeneration potential of canopy gaps at early formation stage in temperate Secondary Forests northeast china
PLOS ONE, 2012Co-Authors: Qiaoling Yan, Jiaojun ZhuAbstract:Promoting the seed regeneration potential of Secondary Forests undergoing gap disturbances is an important approach for achieving forest restoration and sustainable management. Seedling recruitment from seed banks strongly determines the seed regeneration potential, but the process is poorly understood in the gaps of Secondary Forests. The objectives of the present study were to evaluate the effects of gap size, seed availability, and environmental conditions on the seed regeneration potential in temperate Secondary Forests. It was found that gap formation could favor the invasion of more varieties of species in seed banks, but it also could speed up the turnover rate of seed banks leading to lower seed densities. Seeds of the dominant species, Fraxinus rhynchophylla, were transient in soil and there was a minor and discontinuous contribution of the seed bank to its seedling emergence. For Quercus mongolica, emerging seedling number was positively correlated with seed density in gaps (R = 0.32, P<0.01), especially in medium and small gaps (<500 m(2)). Furthermore, under canopies, there was a positive correlation between seedling number and seed density of Acer mono (R = 0.43, P<0.01). Gap formation could promote seedling emergence of two gap-dependent species (i.e., Q. mongolica and A. mono), but the contribution of seed banks to seedlings was below 10% after gap creation. Soil moisture and temperature were the restrictive factors controlling the seedling emergence from seeds in gaps and under canopies, respectively. Thus, the regeneration potential from seed banks is limited after gap formation.
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spatial distribution pattern of soil seed bank in canopy gaps of various sizes in temperate Secondary Forests northeast china
Plant and Soil, 2010Co-Authors: Qiaoling Yan, Jiaojun Zhu, Jianping ZhangAbstract:To promote the natural regeneration of Secondary Forests under gap disturbance is one of important approaches for realizing their restoration and sustainable management. However, soil seed bank, one of regeneration strategies, is poorly understood in gaps of Secondary Forests. Objectives of the study were to evaluate the effects of sizes of experimentally created gaps on seed distribution in soil, and of seed banks on vegetation recovery at early formation stage of gaps in temperate Secondary Forests, Northeast China. It was found that with increasing gap size, species richness in the seed bank significantly increased (r = 0.691, P < 0.05, n = 10), but correspondence in species-composition of seed reservoir between gaps and canopies adjacent to gaps decreased (r = −0.83, P < 0.01, n = 10). Gap size and soil depth and their two-way interactions had significant differences on the distribution of seed bank density (F = 4.101, P < 0.05; F = 34.483, P < 0.01; F = 5.232, P < 0.01, respectively). The Sokal and Sneath similarity indices in species-composition between extant and potential (seed bank) vegetation were generally low, ranging from 0.06 (interior of large gaps) to 0.24 (canopies adjacent to large gaps). From the view of seed bank to restore temperate Secondary Forests, establishment of medium-sized artificial gaps (i.e., gap size with 500–150 m2) could be more feasible for seed invasion. To conclude, the regeneration potential out of soil seed banks is limited, and the restoration of gaps at early formation stage may be mostly dependent on other reproductive strategies (e.g., vegetative propagation of species).
Helmut Elsenbeer - One of the best experts on this subject based on the ideXlab platform.
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soil carbon dynamics under young tropical Secondary Forests on former pastures a case study from panama
Forest Ecology and Management, 2011Co-Authors: Luisa Neumanncosel, Michiel Van Breugel, Jefferson S Hall, Beate Zimmermann, Helmut ElsenbeerAbstract:Abstract Secondary Forests are gaining increased importance in tropical landscapes and have recently been reported to act as potential belowground carbon sinks. While economic interest in the management of Secondary Forests to mitigate carbon emissions is rising, the dynamics of soil carbon stocks under these ecosystems remain poorly understood. Recent studies report conflicting results concerning soil carbon trends as well as multiple confounding factors (e.g. soil type, topography and land-use history) affecting these trends. In this study, organic carbon stocks were measured in the mineral soil up to 20 cm depth of at 24 active pastures, 5–8-year-old, and 12–15-year-old Secondary forest sites on former pastures. Additionally, we estimated carbon stocks under a 100-year-old Secondary forest and compared them to those of nearby mature Forests. Abiotic conditions in the study area were homogenous, enabling us to isolate the effect of land-use change on soil organic carbon stocks. Contrary to our expectations, soil carbon stocks in the top 10 cm did not change with young Secondary forest development. Pasture soils stored 24.8 ± 2.9 Mg ha −1 carbon (mean ± standard error) in the top 10 cm, and no accumulation of soil carbon was apparent during the first 15 years of Secondary succession. Soil carbon stocks under 100-year-old Secondary Forests, averaging 43.0 ± 7.9 Mg ha −1 (mean ± standard error), were clearly higher than those recorded at younger sites and approached levels of soil carbon stocks under mature Forests. These data indicate that soil carbon stocks in this region of Panama are not affected by the land-use transition from pasture to young Secondary regrowth. However, an increase of soil carbon storage might be possible over a longer period of time. Our results support trends observed in other tropical areas and highlight the importance of environmental conditions such as soil properties rather than land-use transitions on soil carbon dynamics. While our understanding of organic carbon dynamics in tropical soils remains limited, these results underscore the challenges of undertaking short-term reforestation projects with the expectation of increasing soil carbon sequestration.
Michiel Van Breugel - One of the best experts on this subject based on the ideXlab platform.
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changing gears during succession shifting functional strategies in young tropical Secondary Forests
Oecologia, 2015Co-Authors: Dylan Craven, Michiel Van Breugel, Jefferson S Hall, Mark S Ashton, Graeme P BerlynAbstract:Adaptations to resource availability strongly shape patterns of community composition along successional gradients in environmental conditions. In the present study, we examined the extent to which variation in functional composition explains shifts in trait-based functional strategies in young tropical Secondary Forests during the most dynamic stage of succession (0–20 years). Functional composition of two size classes in 51 Secondary forest plots was determined using community-weighted means of seven functional traits, which were intensively measured on 55 woody plant species (n = 875–1,761 individuals). Along the successional gradient in forest structure, there was a significant and consistent shift in functional strategies from resource acquisition to resource conservation. Leaf toughness and adult plant size increased significantly, while net photosynthetic capacity (Amass) decreased significantly during succession. Shifts in functional strategies within size classes for Amass and wood density also support the hypothesis that changes in functional composition are shaped by environmental conditions along successional gradients. In general, ‘hard’ functional traits, e.g., Amass and leaf toughness, linked to different facets of plant performance exhibited greater sensitivity to successional changes in forest structure than ‘soft’ traits, such as leaf mass area and leaf dry matter content. Our results also suggested that stochastic processes related to previous land-use history, dispersal limitation, and abiotic factors explained variation in functional composition beyond that attributed to deterministic shifts in functional strategies. Further data on seed dispersal vectors and distance and landscape configuration are needed to improve current mechanistic models of succession in tropical Secondary Forests.
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succession of ephemeral Secondary Forests and their limited role for the conservation of floristic diversity in a human modified tropical landscape
PLOS ONE, 2013Co-Authors: Michiel Van Breugel, Jefferson S Hall, Dylan Craven, Mario Bailon, Andres Hernandez, Michele Abbene, Paulo Van BreugelAbstract:Both local- and landscape-scale processes drive succession of Secondary Forests in human-modified tropical landscapes. Nonetheless, until recently successional changes in composition and diversity have been predominantly studied at the patch level. Here, we used a unique dataset with 45 randomly selected sites across a mixed-use tropical landscape in central Panama to study forest succession simultaneously on local and landscape scales and across both life stages (seedling, sapling, juvenile and adult trees) and life forms (shrubs, trees, lianas, and palms). To understand the potential of these Secondary Forests to conserve tree species diversity, we also evaluated the diversity of species that can persist as viable metapopulations in a dynamic patchwork of short-lived successional Forests, using different assumptions about the average relative size at reproductive maturity. We found a deterministic shift in the diversity and composition of the local plant communities as well as the metacommunity, driven by variation in the rate at which species recruited into and disappeared from the Secondary Forests across the landscape. Our results indicate that dispersal limitation and the successional niche operate simultaneously and shape successional dynamics of the metacommunity of these early Secondary Forests. A high diversity of plant species across the metacommunity of early Secondary Forests shows a potential for restoration of diverse Forests through natural succession, when trees and fragments of older Forests are maintained in the agricultural matrix and land is abandoned or set aside for a long period of time. On the other hand, during the first 32 years the number of species with mature-sized individuals was a relatively small and strongly biased sub-sample of the total species pool. This implies that ephemeral Secondary Forests have a limited role in the long-term conservation of tree species diversity in human-modified tropical landscapes.
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soil carbon dynamics under young tropical Secondary Forests on former pastures a case study from panama
Forest Ecology and Management, 2011Co-Authors: Luisa Neumanncosel, Michiel Van Breugel, Jefferson S Hall, Beate Zimmermann, Helmut ElsenbeerAbstract:Abstract Secondary Forests are gaining increased importance in tropical landscapes and have recently been reported to act as potential belowground carbon sinks. While economic interest in the management of Secondary Forests to mitigate carbon emissions is rising, the dynamics of soil carbon stocks under these ecosystems remain poorly understood. Recent studies report conflicting results concerning soil carbon trends as well as multiple confounding factors (e.g. soil type, topography and land-use history) affecting these trends. In this study, organic carbon stocks were measured in the mineral soil up to 20 cm depth of at 24 active pastures, 5–8-year-old, and 12–15-year-old Secondary forest sites on former pastures. Additionally, we estimated carbon stocks under a 100-year-old Secondary forest and compared them to those of nearby mature Forests. Abiotic conditions in the study area were homogenous, enabling us to isolate the effect of land-use change on soil organic carbon stocks. Contrary to our expectations, soil carbon stocks in the top 10 cm did not change with young Secondary forest development. Pasture soils stored 24.8 ± 2.9 Mg ha −1 carbon (mean ± standard error) in the top 10 cm, and no accumulation of soil carbon was apparent during the first 15 years of Secondary succession. Soil carbon stocks under 100-year-old Secondary Forests, averaging 43.0 ± 7.9 Mg ha −1 (mean ± standard error), were clearly higher than those recorded at younger sites and approached levels of soil carbon stocks under mature Forests. These data indicate that soil carbon stocks in this region of Panama are not affected by the land-use transition from pasture to young Secondary regrowth. However, an increase of soil carbon storage might be possible over a longer period of time. Our results support trends observed in other tropical areas and highlight the importance of environmental conditions such as soil properties rather than land-use transitions on soil carbon dynamics. While our understanding of organic carbon dynamics in tropical soils remains limited, these results underscore the challenges of undertaking short-term reforestation projects with the expectation of increasing soil carbon sequestration.
Haifang Yang - One of the best experts on this subject based on the ideXlab platform.
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Snow/wind damage in natural Secondary Forests in Liaodong mountainous regions of Liaoning Province
Journal of Applied Ecology, 2004Co-Authors: Xiaoli Li, Jiaojun Zhu, Zhi-jie Liu, Haifang YangAbstract:In early spring of 2003,the Secondary Forests at the Qingyuan Experimental Forests (QEF) of the Institute of Applied Ecology,Chinese Academy of Sciences suffered from the damage caused by snow and wind (snow/wind damage).This damage occurred at 800 m above sea level was the most serious one since 1949 In order to make clear its occurrence and process and to analyze its possible influences on the Secondary forest system,comprehensive investigations were conducted soon after the snow/wind damage.The results showed that the occurrence of this damage was due to the special site conditions (higher sea level and steeper slopes) and air temperature,which suited the wet snow formation and the snow accumulation on trees after a large scale of precipitation.The more seriously damaged areas were those with the stands of Acer mono,Juglans mandshurica,Populus spp. and so on.The ratio of damaged trees was negatively correlated with stand density,soil depth and size class of diameter,and positively correlated with tree height.Based on these results,the likely influences of snow/wind damage,i.e.,the happening of diseases and insect pests,the vegetation changing under Forests,and the factors of habitat and dominant species in natural Secondary Forests were also discussed.It is significant that to do observation and basic research on damaged Forests will provide reasonable strategies for management of natural Secondary Forests.
Susan G. Laurance - One of the best experts on this subject based on the ideXlab platform.
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Dispersal and recruitment limitations in Secondary Forests
Journal of Vegetation Science, 2020Co-Authors: Ana C. Palma, Miriam Goosem, Pablo R. Stevenson, Roderick J. Fensham, Steve Goosem, Noel D. Preece, Susan G. LauranceAbstract:Aims: Secondary Forests are expanding rapidly in tropical regions and could play an important role in conserving native biodiversity and stabilising global climate. The recovery rate of plant communities in Secondary Forests varies considerably due to mechanisms associated with seed dispersal and recruitment dynamics. We explored these mechanisms along a chronosequence of tropical Secondary Forests in an agricultural landscape that was extensively cleared. Location: We explored these mechanisms along a chronosequence of Secondary Forests in tropical Australia. Methods: We used selected plant traits to characterise plant species and compared community composition between demographic stages (i.e. soil seedbank, understorey and overstorey) and forest age categories. We collected soil samples to assess seedbank composition and used quadrants and transects to assess understorey and overstorey plant community composition at each site. Results: For all demographic stages, we found that young (4-12 years) and intermediate-aged Forests (16-20 years) were dominated by early successional, small-seeded species and traits associated with disturbed Forests. In old Secondary forest (23-34 years) some traits associated with late successional stages were present (e.g. large seeds, trees). However, the traits and species composition of mature Forests remained distinct from all Secondary Forests. Across the chronosequence, forest age and demographic stage were significant factors in discriminating species and trait composition between forest sites. We found clear plant community similarities within demographic stages, despite the forest age differences. This suggests stronger limitations to dispersal and recruitment between demographic stages than between forest ages. Conclusions: Our results show that Secondary Forests in this region assemble slowly with dispersal and recruitment limitations constraining their recovery. Although a successional transition in species and plant traits composition along the chronosequence is clear, similarities to mature Forests remain low. The slow recovery of late successional and large-seeded species in these Secondary Forests suggests that active restoration of such species may be necessary if we want to enhance the capacity of these Forests to conserve native biodiversity.
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Enhancing plant diversity in Secondary Forests
Frontiers in Forests and Global Change, 2020Co-Authors: Ana C. Palma, Miriam Goosem, Pablo R. Stevenson, Susan G. LauranceAbstract:Dispersal, recruitment and establishment limitations are crucial processes shaping forest composition. In Secondary Forests these mechanisms may operate differently than in mature Forests, because young and isolated Secondary Forests may suffer stronger limitations due to a lack of suitable dispersers and harsh environmental conditions—such as the elevated competition of exotic grasses. To assess establishment limitations in these Forests, we undertook transplant experiments involving seeds and seedlings along a chronosequence of Secondary Forests in tropical Australia. The experiments included six species that varied in seed size (6 to 50 mm in length) and successional status (early to late successional). Seeds of five species were placed in one of three treatments: 1) exposed seeds, 2) fenced seeds and 3) buried seeds, and multiple seedlings of six species were transplanted in block treatments. After 14 - 17 months, seeds from all plant species germinated across all ages of Secondary Forests. However, in young Secondary forest sites (4 - 12 years) fewer germinated seeds survived. The highest survival rates were observed for buried seeds (27.2%) compared to the low survival of exposed seeds (6.0%). Planted seedlings (6 spp) had the greatest overall survival (63.1%) and the highest growth rates in older Secondary Forests. We found that species identity was important for growth and survival in both experiments, but detected no effect of successional status or seed size. A crucial finding of this study was that the buried seeds of all species germinated and had relatively high survival irrespective of variation in site conditions or successional status, suggesting that seed availability may be a greater barrier to recovery of Secondary Forests in the region than the establishment limitations imposed by environmental conditions.
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soil types influence predictions of soil carbon stock recovery in tropical Secondary Forests
Forest Ecology and Management, 2016Co-Authors: Claudia Pandolfo Paz, Miriam Goosem, Steve Goosem, Noel D. Preece, Michael I Bird, Rod Fensham, Susan G. LauranceAbstract:Tropical Forests are major sinks of terrestrial carbon (C) both above- and below-ground. As a consequence their destruction and degradation is considered the second largest anthropogenic source of carbon dioxide to the atmosphere. Also contributing to the changing dynamics of the global carbon cycle is the widespread and significant expansion of Secondary forest. Secondary Forests that colonise abandoned agricultural lands can potentially recover above-ground C stocks to historical levels in a few decades. However, the dynamics of below-ground C stored as soil C stocks are unaccounted for in several tropical regions. Similarly, although parent materials are known to differ in chemical and physical properties, little is known about the relationships of soil C stocks with environmental predictors and whether they interact with soil types during natural forest regeneration. We investigated whether soil organic carbon (SOC) stocks change with Secondary forest age in two contrasting soil types (derived from either basalt or granite). Soil and vegetation parameters were analysed to determine the best predictors of SOC stock changes in Secondary Forests. SOC stocks from 24 Secondary Forests (up to 69 years since pasture abandonment) were compared with those from active pastures and mature Forests. We found that clay-rich soils (originating from basalt parent material) store higher amounts of SOC, although these stocks remain unchanged as Secondary Forests matured. In contrast, SOC stocks in granite soils tend to be lower in young Secondary Forests and increase rapidly to levels comparable to mature Forests. Moreover, our analysis indicated that soil pH and woody plant diversity are strong candidates as predictors of SOC stock variations, yet it appears this is within the context of soil type. Our results support the contention that models predicting SOC stocks during forest succession should not rely only on Secondary forest age. Instead, predictions of SOC stocks can be improved with the inclusion of basic information on vegetation cover and soil type (especially soil texture).
