The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Xingguo Han - One of the best experts on this subject based on the ideXlab platform.
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decreased plant productivity resulting from plant group Removal Experiment constrains soil microbial functional diversity
Global Change Biology, 2017Co-Authors: Ximei Zhang, Eric R Johnston, Albert Barberan, Yi Ren, Xingguo HanAbstract:Anthropogenic environmental changes are accelerating the rate of biodiversity loss on Earth. Plant diversity loss is predicted to reduce soil microbial diversity primarily due to the decreased variety of carbon/energy resources. However, this intuitive hypothesis is supported by sparse empirical evidence, and most underlying mechanisms remain underexplored or obscure altogether. We constructed four diversity gradients (0-3) in a five-year plant functional group Removal Experiment in a steppe ecosystem in Inner Mongolia, China, and quantified microbial taxonomic and functional diversity with shotgun metagenome sequencing. The treatments had little effect on microbial taxonomic diversity, but were found to decrease functional gene diversity. However, the observed decrease in functional gene diversity was more attributable to a loss in plant productivity, rather than to the loss of any individual plant functional group per se. Reduced productivity limited fresh plant resources supplied to microorganisms, and thus, intensified the pressure of ecological filtering, favoring genes responsible for energy production/conversion, material transport/metabolism and amino acid recycling, and accordingly disfavored many genes with other functions. Furthermore, microbial respiration was correlated with the variation in functional composition but not taxonomic composition. Overall, the amount of carbon/energy resources driving microbial gene diversity was identified to be the critical linkage between above- and belowground communities, contrary to the traditional framework of linking plant clade/taxonomic diversity to microbial taxonomic diversity.
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effects of plant functional group loss on soil biota and net ecosystem exchange a plant Removal Experiment in the mongolian grassland
Journal of Ecology, 2016Co-Authors: Dima Chen, Yongfei Bai, Jianhui Huang, Qingmin Pan, Qibing Wang, Shahid Naeem, James J Elser, Xingguo HanAbstract:Summary The rapid loss of global biodiversity can greatly affect the functioning of above-ground components of ecosystems. However, how such biodiversity losses affect below-ground communities and linkages to soil carbon (C) sequestration is unclear. Here, we describe how losses in plant functional groups (PFGs) affect soil microbial and nematode communities and net ecosystem exchange (NEE) in a 4-year Removal Experiment conducted on the Mongolian plateau, the world's largest remaining natural grassland. Our results demonstrated that the biomasses or abundances of most components of the two below-ground communities (microbes and nematodes) were negatively affected by PFG loss and were positively related to above-ground plant biomass. The Removal of dominant PFGs (perennial bunchgrasses and perennial rhizomatous grasses) reduced the biomass or abundance of below-ground community components while Removal of less dominant PFGs (perennial forbs and annuals/biennials) did not change or increased the biomass or abundance of below-ground community components. The biomass-based ratio of fungal to bacterial microbes and the number-based ratio of fungal-feeding to bacterial-feeding nematodes decreased with increasing PFG losses. Variation partitioning analyses showed that the identity of PFGs together with above-ground plant biomass explained most of the total variation in soil microbes and that the identity of PFGs and above-ground plant biomass together with nematode food resources explained most of the total variation in soil nematodes. The increase in NEE with PFG loss was mainly explained by decreases in above-ground plant biomass and the ratio of fungi to bacteria. Synthesis. The shift of below-ground communities from a fungal-based to a bacterial-based energy channel as PFG richness decreases indicates that less diverse grassland ecosystems will have lower nutrient retention and hence be more sensitive to land-use or climate change. The dominant effects of above-ground plant biomass and below-ground communities on NEE indicate that PFG loss resulting from land-use or climate change has the potential to reduce C sequestration in semi-arid grassland soils. These findings suggest that predictive models may need to consider the composition of above-ground and below-ground communities in order to accurately simulate the dynamics of CO2 fluxes in terrestrial ecosystems.
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spatial patterns of soil nutrients plant diversity and aboveground biomass in the inner mongolia grassland before and after a biodiversity Removal Experiment
Landscape Ecology, 2015Co-Authors: Fei Yuan, Helen I Rowe, Yongfei Bai, Jianhui Huang, Xingguo HanAbstract:Spatial heterogeneity is ubiquitous in ecological systems, and has important effects on biological diversity and ecological processes. Does spatial heterogeneity affect the relationship between biodiversity and ecosystem functioning (BEF)? To help address this question, this study investigated how the spatial patterns of key BEF variables changed before and after the biodiversity Removal during a BEF Experiment in China. Our analysis was based on data from the Inner Mongolia grassland Removal Experiment (IMGRE) which was conducted in the Xilingol Steppe, Inner Mongolia, China. We quantified the spatial patterns of key variables of BEF, and examined the spatial relationships among these variables, using biodiversity indices and spatial statistical methods (autocorrelation and semivariance analysis). Our results show that the variables of BEF in the Inner Mongolian grassland had various spatial patterns, most of which were spatially correlated to each other. Removal treatments had significant effects on these spatial structures and correlations. These effects were diverse in terms of both their kinds and magnitudes because of different Removal protocols and treatments. The differences in spatial patterns of plant and soil variables and their correlations before and after the biodiversity manipulation do not necessarily imply that the results from BEF Experiments like IMGRE are invalid, but they do suggest that the possible effects of spatial heterogeneity on the BEF relationship should be further scrutinized in future studies.
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spatial patterns of soil nutrients plant diversity and aboveground biomass in the inner mongolia grassland before and after a biodiversity Removal Experiment
Landscape Ecology, 2015Co-Authors: Fei Yuan, Helen I Rowe, Yongfei Bai, Jianhui Huang, Xingguo HanAbstract:Context Spatial heterogeneity is ubiquitous in ecological systems, and has important effects on biological diversity and ecological processes.
Alexandre Buttler - One of the best experts on this subject based on the ideXlab platform.
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subordinate plant species impact on soil microbial communities and ecosystem functioning in grasslands findings from a Removal Experiment
Perspectives in Plant Ecology Evolution and Systematics, 2013Co-Authors: Richard D Bardgett, Pierre Mariotte, Charlotte Vandenberghe, Claire Meugnier, Pierre Rossi, Alexandre ButtlerAbstract:Despite their low relative abundance, subordinate plant species may have larger impacts on ecosystem functioning than expected, but their role in plant communities remains poorly understood. The aim of this study was to test how subordinate plant species influence the functioning of a species-rich semi-natural grasslands. A plant Removal Experiment was set-up in the mountain grasslands of the Jura Mountains (Switzerland) to test the impact of subordinate plant species on soil microbial communities and ecosystem functioning. The Experiment included three treatments: Removal of all subordinate species, partial biomass Removal of dominant species, and a no biomass Removal control. After 2 years of treatments, we determined soil microbial community (bacteria and mycorrhizal fungi) by T-RFLP analysis and measured litter decomposition, soil respiration, soil inorganic nitrogen (DIN) availability and throughout aboveground biomass production as measures of ecosystem function. The Removal of subordinate plant species strongly affected bacterial and weakly influenced mycorrhizal fungi communities and decreased rates of plant litter decomposition, soil respiration and DIN availability with larger effects than the partial loss of dominant biomass. The Removal of subordinate plant species did not modify plant community structure, but it did reduce total above-ground biomass production compared to the control plots. Collectively, our findings indicate that the loss of subordinate species can have significant consequences for soil microbial communities and ecosystem functions, suggesting that subordinate species are important drivers of ecosystem properties. (C) 2012 Elsevier GmbH. All rights reserved.
Stefan A Schnitzer - One of the best experts on this subject based on the ideXlab platform.
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contribution of lianas to plant area index and canopy structure in a panamanian forest
Ecology, 2016Co-Authors: Stefan A Schnitzer, Jennifer S Powers, Elizabeth M Rodriguezronderos, Gil Bohrer, Arturo SanchezazofeifaAbstract:Lianas are an important component of tropical forests, where they reduce tree growth, fecundity, and survival. Competition for light from lianas may be intense; however, the amount of light that lianas intercept is poorly understood. We used a large-scale liana-Removal Experiment to quantify light interception by lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure before and after cutting lianas (for four years) in eight 80x80 m plots and eight control plots (16 plots total). We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting lianas, and then annually for two years afterwards. Six weeks after cutting lianas, mean plot PAI was 20% higher in control versus liana Removal plots. One year after cutting lianas, mean plot PAI was ~17% higher in control plots. The differences between treatments diminished significantly two years after liana cutting and, after four years, trees had fully compensated for liana Removal. Ground-based LiDAR revealed that lianas attenuated light in the upper- and middle-forest canopy layers, and not only in the upper-canopy as was previously suspected. Thus, lianas compete with trees by intercepting light in the upper- and mid-canopy of this forest. This article is protected by copyright. All rights reserved.
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lianas reduce carbon accumulation and storage in tropical forests
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Geertje M F Van Der Heijden, Jennifer S Powers, Stefan A SchnitzerAbstract:Tropical forests store vast quantities of carbon, account for one-third of the carbon fixed by photosynthesis, and are a major sink in the global carbon cycle. Recent evidence suggests that competition between lianas (woody vines) and trees may reduce forest-wide carbon uptake; however, estimates of the impact of lianas on carbon dynamics of tropical forests are crucially lacking. Here we used a large-scale liana Removal Experiment and found that, at 3 y after liana Removal, lianas reduced net above-ground carbon uptake (growth and recruitment minus mortality) by ∼76% per year, mostly by reducing tree growth. The loss of carbon uptake due to liana-induced mortality was four times greater in the control plots in which lianas were present, but high variation among plots prevented a significant difference among the treatments. Lianas altered how aboveground carbon was stored. In forests where lianas were present, the partitioning of forest aboveground net primary production was dominated by leaves (53.2%, compared with 39.2% in liana-free forests) at the expense of woody stems (from 28.9%, compared with 43.9%), resulting in a more rapid return of fixed carbon to the atmosphere. After 3 y of Experimental liana Removal, our results clearly demonstrate large differences in carbon cycling between forests with and without lianas. Combined with the recently reported increases in liana abundance, these results indicate that lianas are an important and increasing agent of change in the carbon dynamics of tropical forests.
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liana competition with tropical trees varies seasonally but not with tree species identity
Ecology, 2015Co-Authors: Stefan A Schnitzer, Jennifer S Powers, Leonor Alvarezcansino, Joseph P ReidAbstract:Lianas in tropical forests compete intensely with trees for above- and belowground resources and limit tree growth and regeneration. Liana competition with adult canopy trees may be particularly strong, and, if lianas compete more intensely with some tree species than others, they may influence tree species composition. We performed the first systematic, large-scale liana Removal Experiment to assess the competitive effects of lianas on multiple tropical tree species by measuring sap velocity and growth in a lowland tropical forest in Panama. Tree sap velocity increased 60% soon after liana Removal compared to control trees, and tree diameter growth increased 25% after one year. Although tree species varied in their response to lianas, this variation was not significant, suggesting that lianas competed similarly with all tree species examined. The effect of lianas on tree sap velocity was particularly strong during the dry season, when soil moisture was low, suggesting that lianas compete intensely with trees for water. Under the predicted global change scenario of increased temperature and drought intensity, competition from lianas may become more prevalent in seasonal tropical forests, which, according to our data, should have a negative effect on most tropical tree species.
Emma J Sayer - One of the best experts on this subject based on the ideXlab platform.
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arbuscular mycorrhizal fungal community composition is altered by long term litter Removal but not litter addition in a lowland tropical forest
New Phytologist, 2017Co-Authors: Merlin Sheldrake, Nicholas P Rosenstock, Daniel Revillini, Pal Axel Olsson, Scott A Mangan, Emma J SayerAbstract:Tropical forest productivity is sustained by the cycling of nutrients through decomposing organic matter. Arbuscular mycorrhizal (AM) fungi play a key role in the nutrition of tropical trees, yet there has been little Experimental investigation into the role of AM fungi in nutrient cycling via decomposing organic material in tropical forests. We evaluated the responses of AM fungi in a long-term leaf litter addition and Removal Experiment in a tropical forest in Panama. We described AM fungal communities using 454-pyrosequencing, quantified the proportion of root length colonised by AM fungi using microscopy, and estimated AM fungal biomass using a lipid biomarker. AM fungal community composition was altered by litter Removal but not litter addition. Root colonisation was substantially greater in the superficial organic layer compared with the mineral soil. Overall colonisation was lower in the litter Removal treatment, which lacked an organic layer. There was no effect of litter manipulation on the concentration of the AM fungal lipid biomarker in the mineral soil. We hypothesise that reductions in organic matter brought about by litter Removal may lead to AM fungi obtaining nutrients from recalcitrant organic or mineral sources in the soil, besides increasing fungal competition for progressively limited resources.
Bo Wang - One of the best experts on this subject based on the ideXlab platform.
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seed density affects post dispersal seed predation evidence from a seed Removal Experiment of 62 species
Integrative Zoology, 2020Co-Authors: Bo WangAbstract:Post-dispersal seed predation plays an important role in plant demography and biodiversity maintenance. However, the effects of seed density on seed predation from previous studies have been inconsistent. We dissected the effects of density on the 2-step processes of seed predation using 101 520 seeds from 62 plant species in an alpine pine forest for 3 consecutive years. In this study we explained the current controversy surrounding the effects of density on seed predation. Seed encounter frequency (at least 1 seed being predated from an Experiment depot) showed positive density dependence, while seed exploitation (the proportion of seeds being predated of the encountered depots) showed negative density dependence. Both density effects showed a consistent trend but with different magnitudes of effect across years. Final seed predation is the combination of seed encounter and seed exploitation. Final seed predation could be either positively or negatively density-dependent and was contingent on the magnitude of the difference between positive density-dependent seed encounter and negative density-dependent seed exploitation. Our results also indicated that studies including only a few species would produce biased results, because the density effect on seed predation differed greatly among plant species. Future studies should include a large number of plant species that possess a wide range of diverse seed traits to avoid potential bias and produce more comprehensive and accurate results.
