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Jeffrey A Bird - One of the best experts on this subject based on the ideXlab platform.
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exotic earthworm community composition interacts with soil texture to affect redistribution and retention of litter derived c and n in northern Temperate Forest soils
Biogeochemistry, 2015Co-Authors: Jeffrey A Bird, Jasmine M Crumsey, Yvan Capowiez, Mitch Goodsitt, S Larson, James Le M Moine, George W Kling, Knute J NadelhofferAbstract:Exotic earthworm impacts on Temperate Forest soils are influenced by earthworm community composition and are likely constrained by the degree of organic matter redistribution following earthworm introductions across different soil types; however, the relative importance of these factors remains unknown. We examined how exotic earthworm communities affected leaf litter carbon (C) and nitrogen (N) mineralization and transport in two Spodosols with contrasting textures and organic matter contents. In reconstructed soil mesocosms, we measured organic C pools, quantified 13C and 15N transport from isotopically labeled red maple (Acer rubrum) leaf litter, and linked leaf litter redistribution to sub-surface burrow system structures following 150-day incubations. Transport of C and N from surface litter into soil was greatest with multi-species earthworm communities, and A-horizon and burrow pools functioned as dominant sinks for this material. Litter-derived C:N recovery ratios of soil pools revealed higher retention of litter-derived N over litter-derived C; recovery of litter N (mg 15N m−2) transported from surface litter was greater in the sandy loam (98.2 ± 2.73 %) than in the sandy soil (66.2 ± 4.92 %) following earthworm community additions. Earthworm biomass was as a minor sink for litter C (mg 13C m−2) and N transported from surface litter (0.56 ± 0.13 and 2.26 ± 0.31 %, respectively). Recovery of litter-derived C and N in earthworm biomass increased with the degree of direct leaf litter consumption (A. trapezoides < E. fetida < L. terrestris). Surface-dwelling epigeic and mineral-soil dwelling endogeic species produced burrow systems with the highest volume, surface connectivity, and density in the A-horizon; these properties were associated with greater CO2 losses and with greater litter C and N transport into A-horizons and burrows. Burrow systems with high continuity and large burrows produced by vertical-burrowing anecic species were associated with greater litter C and N transport into B-horizons, and greater dissolved organic C leaching losses. This study shows that the degree of organic matter redistribution in Temperate Forest soils following earthworm introductions is directly related to earthworm community composition, while the preferential retention of N over C and the potential stabilization of this material is determined by soil type.
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transformation and stabilization of pyrogenic organic matter in a Temperate Forest field experiment
Global Change Biology, 2014Co-Authors: Nimisha Singh, M S Torn, Jeffrey A Bird, Samuel Abiven, Bernardo Maestrini, Michael W I SchmidtAbstract:Pyrogenic organic matter (PyOM) decomposes on centennial timescale in soils, but the processes regulating its decay are poorly understood. We conducted one of the first studies of PyOM and wood decomposition in a Temperate Forest using isotopically labeled organic substrate, and quantified microbial incorporation and physico-chemical transformations of PyOM in situ. Stable-isotope (13C and 15N) enriched PyOM and its precursor wood were added to the soil at 2 cm depth at ambient (N0) and increased (N+) levels of nitrogen fertilization. The carbon (C) and nitrogen (N) of added PyOM or wood were tracked through soil to 15 cm depth, in physically separated soil density fractions and in benzene polycarboxylic acids (BPCA) molecular markers. After 10 months in situ, more PyOM-derived C (>99% of initial 13C-PyOM) and N (90% of initial 15N-PyOM) was recovered than wood derived C (48% of 13C-wood) and N (89% under N0 and 48% under N+). PyOM-C and wood-C migrated at the rate of 126 mm yr-1 with 3-4% of PyOM-C and 4-8% of wood-C recovered below the application depth. Most PyOM C was recovered in the free light fraction (fLF) (74%), with 20% in aggregate-occluded and 6% in mineral associated fractions —fractions that typically have much slower turnover times. In contrast, wood C was recovered mainly in occluded (33%) or dense fraction (27%). PyOM addition induced loss of native C from soil (priming effect), particularly in fLF (13%). The total BPCA-C content did not change but after ten months the degree of aromatic condensation of PyOM decreased, as determined by relative contribution of benzene hexa-carboxylic acid (B6CA) to the total BPCA C. Soil microbial biomass (SMB) assimilated 6-10% of C from the wood, while PyOM contributions was negligible (0.14–0.18%). The addition of N had no effect on the dynamics of PyOM while limited effect on wood.
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biological degradation of pyrogenic organic matter in Temperate Forest soils
Soil Biology & Biochemistry, 2012Co-Authors: Fernanda Santos, M S Torn, Jeffrey A BirdAbstract:Abstract Pyrogenic organic matter (PyOM), derived from the incomplete combustion of plant biomass and fossil fuels, has been considered one of the most stable pools of soil organic matter (SOM) and a potentially important terrestrial sink for atmospheric CO 2 . Recent evidence suggests that PyOM may degrade faster in soil than previously thought, and can affect native SOM turnover rates. We conducted a six-month laboratory incubation study to better understand the processes controlling the degradation of PyOM in soils using dual-enriched ( 13 C/ 15 N) PyOM and its precursor wood ( Pinus ponderosa ). We examined the effects of soil type and inorganic N addition on PyOM and wood C and N mineralization rates, microbial C utilization patterns, and native SOM turnover rates. PyOM charred at 450 °C or its precursor pine wood was incubated in two Temperate Forest subsoils with contrasting short range order (SRO) clay mineralogy (granite versus andesite parent material). Duplicates of experimental treatments with and without PyOM added were sterilized and abiotic C mineralization was quantified. In a second incubation, PyOM or wood was incubated in granitic soil with and without added NH 4 NO 3 (20 kg N ha −1 ). The fate of 13 C/ 15 N-enriched PyOM and wood was followed as soil-respired 13 CO 2 and total extractable inorganic 15 N. The uptake of 13 C from PyOM and wood by soil microbial community groups was quantified using 13 C-phospholipids fatty acids (PLFA). We found that (1) The mean residence time (MRT) of PyOM-C was on a centennial time scale (390–600 yr) in both soil types; (2) PyOM-C mineralization was mainly biologically mediated; (3) Fungi more actively utilized wood-C than PyOM-C, which was utilized by all bacteria groups, especially gram (+) bacteria in the andesite (AN) soil; (4) PyOM-N mineralization was 2 times greater in granite (GR) than in AN soils; (5) PyOM additions did not affect native soil C or N mineralization rates, microbial biomass, or PLFA-defined microbial community composition in either soil; (6) The addition of N to GR soil had no effect on the MRT of C from PyOM, wood, or native SOM. The centennial scale MRT for PyOM-C was 32 times slower than that for the precursor pine wood-C or native soil C, which is faster than the MRT used in ecosystem models. Our results show that PyOM-C is readily utilized by all heterotrophic microbial groups, and PyOM-C and -N may be more dynamic in soils than previously thought.
Estelle Forey - One of the best experts on this subject based on the ideXlab platform.
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Solar UV-A radiation and blue light enhance tree leaf litter decomposition in a Temperate Forest
Oecologia, 2019Co-Authors: Marta Pieristè, Titta K. Kotilainen, Michaël Aubert, T. Matthew Robson, Alan G. Jones, Matthieu Chauvat, Estelle ForeyAbstract:Sunlight can accelerate the decomposition process through an ensemble of direct and indirect processes known as photodegradation. Although photodegradation is widely studied in arid environments, there have been few studies in Temperate regions. This experiment investigated how exposure to solar radiation, and specifically UV-B, UV-A, and blue light, affects leaf litter decomposition under a Temperate Forest canopy in France. For this purpose, we employed custom-made litterbags built using filters that attenuated different regions of the solar spectrum. Litter mass loss and carbon to nitrogen (C:N) ratio of three species: European ash (Fraxinus excelsior), European beech (Fagus sylvatica) and pedunculate oak (Quercus robur), differing in their leaf traits and decomposition rate, were analysed over a period of 7–10 months. Over the entire period, the effect of treatments attenuating blue light and solar UV radiation on leaf litter decomposition was similar to that of our dark treatment, where litter lost 20–30% less mass and had a lower C:N ratio than under the full-spectrum treatment. Moreover, decomposition was affected more by the filter treatment than mesh size, which controlled access by mesofauna. The effect of filter treatment differed among the three species and appeared to depend on litter quality (and especially C:N), producing the greatest effect in recalcitrant litter (F. sylvatica). Even under the reduced irradiance found in the understorey of a Temperate Forest, UV radiation and blue light remain important in accelerating surface litter decomposition.
Peter B Reich - One of the best experts on this subject based on the ideXlab platform.
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tree species diversity enhances plant soil interactions in a Temperate Forest in northeast china
Forest Ecology and Management, 2021Co-Authors: Anvar Sanaei, Arshad Ali, Fei Lin, Zuoqiang Yuan, Michel Loreau, Akira Mori, Peter B Reich, Tommaso Jucker, Shuai FangAbstract:Abstract The plant-soil interactions may drive the diversity and functioning of Forests, but we do not fully understand how interrelationships between plant and soil compartments are underlined by multiple ecological mechanisms. Here, we hypothesize that positive plant-soil interactions enhance biodiversity and functioning in a Temperate Forest. To do so, we tested the relationships between plant diversity (i.e., tree and herb species richness) and functions (i.e., coarse woody productivity and litterfall productivity), and soil diversity (i.e. bacterial, fungal and nematode) and functions (i.e. soil nutrient and carbon stock), and their interrelationships in a Temperate Forest in northeast China. The positive relationship between diversity and functioning was predominant within plant and soil compartments, and hence, provide support to the niche complementarity effect. As such, the positive interrelationships between the diversity of soil and plant compartments provide support to the positive plant-soil interactions. Tree species diversity was positively related with herb species diversity and coarse-woody productivity. Importantly, tree species diversity had pronounced positive effect on soil biodiversity resulting in increased soil carbon stocks, indicating that tree species diversity effect matters for linking positive interrelationships between plant and soil compartments of a Temperate Forest. This study shows that tree diversity effect is the main regulating biotic mechanism for linking the positive connections between plant and soil compartments of a Temperate Forest, and hence, the niche complementarity effect can enhance Forest functioning through positive interactions on resource supply. We argue that linking the multiple key functions and diversity indices of Forests can enhance our knowledge on the main influential factors and underlying ecological mechanisms.
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experimental warming advances phenology of groundlayer plants at the boreal Temperate Forest ecotone
American Journal of Botany, 2018Co-Authors: Karen Rice, Peter B Reich, Rebecca A Montgomery, Artur Stefanski, Roy L RichAbstract:PREMISE OF THE STUDY Changes to plant phenology have been linked to warmer temperatures caused by climate change. Despite the importance of the groundlayer to community and Forest dynamics, few warming experiments have focused on herbaceous plant and shrub phenology. METHODS Using a field study in Minnesota, United States, we investigated phenological responses of 16 species to warming over five growing seasons (2009-2013) at two sites, under two canopy covers, and in three levels of simultaneous above- and belowground warming: ambient temperature, ambient +1.7°C and ambient +3.4°C. We tested whether warming led to earlier phenology throughout the growing season and whether responses varied among species and years and depended on canopy cover. KEY RESULTS Warming extended the growing season between 11-30 days, primarily through earlier leaf unfolding. Leaf senescence was delayed for about half of the species. Warming advanced flowering across species, especially those flowering in August, with modest impacts on fruit maturation for two species. Importantly, warming caused more than half of the species to either converge or diverge phenologically in relation to each other, suggesting that future warmed climate conditions will alter phenological relationships of the groundlayer. Warm springs elicited a stronger advance of leaf unfolding compared to cool spring years. Several species advanced leaf unfolding (in response to warming) more in the closed canopy compared to the open. CONCLUSIONS Climate warming will extend the growing season of groundlayer species in the boreal-Temperate Forest ecotone and alter the synchrony of their phenology.
Zuoqiang Yuan - One of the best experts on this subject based on the ideXlab platform.
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tree species diversity enhances plant soil interactions in a Temperate Forest in northeast china
Forest Ecology and Management, 2021Co-Authors: Anvar Sanaei, Arshad Ali, Fei Lin, Zuoqiang Yuan, Michel Loreau, Akira Mori, Peter B Reich, Tommaso Jucker, Shuai FangAbstract:Abstract The plant-soil interactions may drive the diversity and functioning of Forests, but we do not fully understand how interrelationships between plant and soil compartments are underlined by multiple ecological mechanisms. Here, we hypothesize that positive plant-soil interactions enhance biodiversity and functioning in a Temperate Forest. To do so, we tested the relationships between plant diversity (i.e., tree and herb species richness) and functions (i.e., coarse woody productivity and litterfall productivity), and soil diversity (i.e. bacterial, fungal and nematode) and functions (i.e. soil nutrient and carbon stock), and their interrelationships in a Temperate Forest in northeast China. The positive relationship between diversity and functioning was predominant within plant and soil compartments, and hence, provide support to the niche complementarity effect. As such, the positive interrelationships between the diversity of soil and plant compartments provide support to the positive plant-soil interactions. Tree species diversity was positively related with herb species diversity and coarse-woody productivity. Importantly, tree species diversity had pronounced positive effect on soil biodiversity resulting in increased soil carbon stocks, indicating that tree species diversity effect matters for linking positive interrelationships between plant and soil compartments of a Temperate Forest. This study shows that tree diversity effect is the main regulating biotic mechanism for linking the positive connections between plant and soil compartments of a Temperate Forest, and hence, the niche complementarity effect can enhance Forest functioning through positive interactions on resource supply. We argue that linking the multiple key functions and diversity indices of Forests can enhance our knowledge on the main influential factors and underlying ecological mechanisms.
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monitoring tree crown scale autumn leaf phenology in a Temperate Forest with an integration of planetscope and drone remote sensing observations
Isprs Journal of Photogrammetry and Remote Sensing, 2021Co-Authors: Jing Wang, Zuoqiang Yuan, Zhengbing Yan, Guangqin Song, Yang Chen, Meifeng Deng, Yingyi Zhao, Zhengfei Guo, Guanhua Dai, Xi YangAbstract:Abstract In Temperate Forests, autumn leaf phenology signals the end of leaf growing season and shows large variability across tree-crowns, which importantly mediates photosynthetic seasonality, hydrological regulation, and nutrient cycling of Forest ecosystems. However, critical challenges remain with the monitoring of autumn leaf phenology at the tree-crown scale due to the lack of spatially explicit information for individual tree-crowns and high (spatial and temporal) resolution observations with nadir view. Recent availability of the PlanetScope constellation with a 3 m spatial resolution and near-daily nadir view coverage might help address these observational challenges, but remains underexplored. Here we developed an integration of PlanetScope with drone observations for improved monitoring of crown-scale autumn leaf phenology in a Temperate Forest in Northeast China. This integration includes: 1) visual identification of individual tree-crowns (and species) from drone observations; 2) extraction of time series of PlanetScope vegetation indices (VIs) for each identified tree-crown; 3) derivation of three metrics of autumn leaf phenology from the extracted VI time series, including the start of fall (SOF), middle of fall (MOF), and end of fall (EOF); and 4) accuracy assessments of the PlanetScope-derived phenology metrics with reference from local phenocams. Our results show that (1) the PlanetScope-drone integration captures large inter-crown phenological variations, with a range of 28 days, 25 days, and 30 days for SOF, MOF, and EOF, respectively, (2) the extracted crown-level phenology metrics strongly agree with those derived from local phenocams, with a root-mean-square-error (RMSE) of 4.1 days, 3.0 days and 5.4 days for SOF, MOF, and EOF, respectively, and (3) PlanetScope maps large variations in autumn leaf phenology over the entire Forest landscape with spatially explicit information. These results demonstrate the ability of our proposed method in monitoring the large spatial heterogeneity of crown-scale autumn leaf phenology in the Temperate Forest, suggesting the potential of using high-resolution satellites to advance crown-scale phenology studies over large geographical areas.
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similarity between seed rain and neighbouring mature tree communities in an old growth Temperate Forest
Journal of Forestry Research, 2020Co-Authors: Yunyun Wang, Jalene M Lamontagne, Fei Lin, Zuoqiang Yuan, Xugao Wang, Zhanqing HaoAbstract:Seed distribution and deposition patterns around parent trees are strongly affected by functional traits and therefore influence the development of plant communities. To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain, we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a Temperate Forest in the Changbai Mountain. Among 480,598 seeds belonging to 12 families, 17 genera, and 26 species were identified, only 54% of the species with mature trees in the community were represented in seeds collected over the 9 years, indicating a limitation in seed dispersal. Understory species were most limited; overstory species were least limited. Species with wind-dispersed seed had the least limitation, while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species; fleshy-fruited species had stronger dispersal limitations than dry-fruited species. Generalized linear mixed models showed that relative basal area had a significant positive effect on seed abundance in traps, while the contribution of diaspore traits was low for nearly all groups. These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here. These findings strengthen the knowledge that tree traits are key in explaining seed deposition patterns, at least at the primary dispersal stage. This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in Temperate Forests.
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tree species traits affect which natural enemies drive the janzen connell effect in a Temperate Forest
Nature Communications, 2020Co-Authors: Shihong Jia, Zhanqing Hao, Fei Lin, Zuoqiang Yuan, Xugao Wang, Guigang Lin, Robert BagchiAbstract:A prominent tree species coexistence mechanism suggests host-specific natural enemies inhibit seedling recruitment at high conspecific density (negative conspecific density dependence). Natural-enemy-mediated conspecific density dependence affects numerous tree populations, but its strength varies substantially among species. Understanding how conspecific density dependence varies with species’ traits and influences the dynamics of whole communities remains a challenge. Using a three-year manipulative community-scale experiment in a Temperate Forest, we show that plant-associated fungi, and to a lesser extent insect herbivores, reduce seedling recruitment and survival at high adult conspecific density. Plant-associated fungi are primarily responsible for reducing seedling recruitment near conspecific adults in ectomycorrhizal and shade-tolerant species. Insects, in contrast, primarily inhibit seedling recruitment of shade-intolerant species near conspecific adults. Our results suggest that natural enemies drive conspecific density dependence in this Temperate Forest and that which natural enemies are responsible depends on the mycorrhizal association and shade tolerance of tree species. The Janzen-Connell hypothesis posits that seedlings may be less likely to establish near conspecifics due to shared natural enemies. Here, Jia et al. show that tree species traits determine whether fungal pathogens or insect herbivores inhibit seedling recruitment and survival in a Temperate Forest.
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tree mycorrhizal associations mediate soil fertility effects on Forest community structure in a Temperate Forest
New Phytologist, 2019Co-Authors: Zikun Mao, Zhanqing Hao, Fei Lin, Zuoqiang Yuan, Adriana Corrales, Kai Zhu, Xugao WangAbstract:Soil fertility influences plant community structure, yet few studies have focused on how this influence is affected by the type of mycorrhizal association formed by tree species within local communities. We examined the relationship of aboveground biomass (AGB) and diversity of adult trees with soil fertility (nitrogen, phosphorus, organic matter, etc.) in the context of different spatial distributions of arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) trees in a Temperate Forest in Northeast China. Diversity showed a positive trend along the soil fertility gradient driven mostly by a positive relationship between AM tree abundance and soil fertility. By contrast, the AGB showed a negative trend along the soil fertility gradient driven mostly by a negative relationship between EM tree AGB and soil fertility. Furthermore, the opposite trend in the AGB and tree species diversity along the soil fertility gradient led to an overall negative diversity-biomass relationship at the 50-m scale but not the 20-m scale. These results suggest that tree mycorrhizal associations play a critical role in driving Forest community structure along soil fertility gradients and highlight the importance of tree mycorrhizal associations in influencing how the diversity-ecosystem function (e.g. biomass) relationships change with soil fertility.
Zhanqing Hao - One of the best experts on this subject based on the ideXlab platform.
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similarity between seed rain and neighbouring mature tree communities in an old growth Temperate Forest
Journal of Forestry Research, 2020Co-Authors: Yunyun Wang, Jalene M Lamontagne, Fei Lin, Zuoqiang Yuan, Xugao Wang, Zhanqing HaoAbstract:Seed distribution and deposition patterns around parent trees are strongly affected by functional traits and therefore influence the development of plant communities. To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain, we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a Temperate Forest in the Changbai Mountain. Among 480,598 seeds belonging to 12 families, 17 genera, and 26 species were identified, only 54% of the species with mature trees in the community were represented in seeds collected over the 9 years, indicating a limitation in seed dispersal. Understory species were most limited; overstory species were least limited. Species with wind-dispersed seed had the least limitation, while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species; fleshy-fruited species had stronger dispersal limitations than dry-fruited species. Generalized linear mixed models showed that relative basal area had a significant positive effect on seed abundance in traps, while the contribution of diaspore traits was low for nearly all groups. These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here. These findings strengthen the knowledge that tree traits are key in explaining seed deposition patterns, at least at the primary dispersal stage. This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in Temperate Forests.
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tree species traits affect which natural enemies drive the janzen connell effect in a Temperate Forest
Nature Communications, 2020Co-Authors: Shihong Jia, Zhanqing Hao, Fei Lin, Zuoqiang Yuan, Xugao Wang, Guigang Lin, Robert BagchiAbstract:A prominent tree species coexistence mechanism suggests host-specific natural enemies inhibit seedling recruitment at high conspecific density (negative conspecific density dependence). Natural-enemy-mediated conspecific density dependence affects numerous tree populations, but its strength varies substantially among species. Understanding how conspecific density dependence varies with species’ traits and influences the dynamics of whole communities remains a challenge. Using a three-year manipulative community-scale experiment in a Temperate Forest, we show that plant-associated fungi, and to a lesser extent insect herbivores, reduce seedling recruitment and survival at high adult conspecific density. Plant-associated fungi are primarily responsible for reducing seedling recruitment near conspecific adults in ectomycorrhizal and shade-tolerant species. Insects, in contrast, primarily inhibit seedling recruitment of shade-intolerant species near conspecific adults. Our results suggest that natural enemies drive conspecific density dependence in this Temperate Forest and that which natural enemies are responsible depends on the mycorrhizal association and shade tolerance of tree species. The Janzen-Connell hypothesis posits that seedlings may be less likely to establish near conspecifics due to shared natural enemies. Here, Jia et al. show that tree species traits determine whether fungal pathogens or insect herbivores inhibit seedling recruitment and survival in a Temperate Forest.
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tree mycorrhizal associations mediate soil fertility effects on Forest community structure in a Temperate Forest
New Phytologist, 2019Co-Authors: Zikun Mao, Zhanqing Hao, Fei Lin, Zuoqiang Yuan, Adriana Corrales, Kai Zhu, Xugao WangAbstract:Soil fertility influences plant community structure, yet few studies have focused on how this influence is affected by the type of mycorrhizal association formed by tree species within local communities. We examined the relationship of aboveground biomass (AGB) and diversity of adult trees with soil fertility (nitrogen, phosphorus, organic matter, etc.) in the context of different spatial distributions of arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) trees in a Temperate Forest in Northeast China. Diversity showed a positive trend along the soil fertility gradient driven mostly by a positive relationship between AM tree abundance and soil fertility. By contrast, the AGB showed a negative trend along the soil fertility gradient driven mostly by a negative relationship between EM tree AGB and soil fertility. Furthermore, the opposite trend in the AGB and tree species diversity along the soil fertility gradient led to an overall negative diversity-biomass relationship at the 50-m scale but not the 20-m scale. These results suggest that tree mycorrhizal associations play a critical role in driving Forest community structure along soil fertility gradients and highlight the importance of tree mycorrhizal associations in influencing how the diversity-ecosystem function (e.g. biomass) relationships change with soil fertility.
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species associations in an old growth Temperate Forest in north eastern china
Journal of Ecology, 2010Co-Authors: Xugao Wang, Zhanqing Hao, Thorsten Wiegand, Fei LinAbstract:Summary 1. Studying the spatial pattern of plants may provide significant insights into processes and mechanisms that maintain species richness. We used data from a fully mapped 25-ha Temperate Forest plot at Changbaishan (CBS), north-eastern China, to conduct a community-wide assessment of the type and frequency of intra- and interspecific spatial association patterns. We analysed complex scale effects in the patterning of large trees of 15 common species. First, we tested for overall spatial patterning at 6, 30 and 50 m neighbourhoods and classified the types of bivariate association patterns at these spatial scales (analysis 1). We then explored small-scale (0–20 m) association patterns conditioning on the larger-scale pattern (analysis 2) and tested for positive large-scale (50–250 m) association patterns (analysis 3). 2. Analysis 1 provided ample evidence for non-random spatial patterning, and the type and frequency of spatial association patterns changed with scale. Trees of most species pairs co-occurred less than expected by chance and positive associations were rare in local neighbourhoods. Analysis 2 revealed a separation of scales in which significant small-scale interactions faded away at distances of 10–15 m. One third of all species pairs showed significant and mostly negative bivariate small-scale association, which occurred more often than expected by chance between species sharing attributes such as family, fruit type and habitat association. This suggests the occurrence of competitive interactions. Analysis 3 showed that only 8% of all species pairs co-occurred at large scales. 3. Comparison of our results with an analogous study conducted in the species-rich tropical Forest at Sinharaja, Sri Lanka, revealed several structural similarities including the dominance of segregation and partial overlap in the overall patterning (analysis 1) and the separation of scales (analysis 2). However, species pairs at CBS showed considerably more significant negative small-scale associations (31% vs. 6% at Sinharaja). 4. Synthesis. The techniques presented here allow for a detailed analysis of the complex spatial associations in species-rich Forests and have the potential to reveal indicative patterns that may allow researchers to discriminate among competing hypotheses of community assemblage and dynamics. However, this will require comparative studies involving a large number of plots.
