The Experts below are selected from a list of 262182 Experts worldwide ranked by ideXlab platform
David Tilman - One of the best experts on this subject based on the ideXlab platform.
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resource availability controls fungal diversity across a Plant diversity gradient
Ecology Letters, 2006Co-Authors: Mark P Waldrop, Donald R Zak, Christopher B Blackwood, Casey Curtis, David TilmanAbstract:Despite decades of research, the ecological determinants of microbial diversity remain poorly understood. Here, we test two alternative hypotheses concerning the factors regulating fungal diversity in soil. The first states that higher levels of Plant detritus production increase the supply of limiting resources (i.e. organic substrates) thereby increasing fungal diversity. Alternatively, greater Plant diversity increases the range of organic substrates entering soil, thereby increasing the number of niches to be filled by a greater array of heterotrophic fungi. These two hypotheses were simultaneously examined in Experimental Plant communities consisting of one to 16 species that have been maintained for a decade. We used ribosomal intergenic spacer analysis (RISA), in combination with cloning and sequencing, to quantify fungal community composition and diversity within the Experimental Plant communities. We used soil microbial biomass as a temporally integrated measure of resource supply. Plant diversity was unrelated to fungal diversity, but fungal diversity was a unimodal function of resource supply. Canonical correspondence analysis (CCA) indicated that Plant diversity showed a relationship to fungal community composition, although the occurrence of RISA bands and operational taxonomic units (OTUs) did not differ among the treatments. The relationship between fungal diversity and resource availability parallels similar relationships reported for grasslands, tropical forests, coral reefs, and other biotic communities, strongly suggesting that the same underlying mechanisms determine the diversity of organisms at multiple scales.
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diversity decreases invasion via both sampling and complementarity effects
Ecology Letters, 2005Co-Authors: Joseph Fargione, David TilmanAbstract:Complementarity and sampling effects may both contribute to increased invasion resistance at higher diversity. We measured Plant invader biomass across a long-term Experimental Plant diversity gradient. Invader species biomass was inhibited in more diverse plots, largely because of the presence of strongly competitive C4 bunchgrasses, consistent with a sampling effect. Invader biomass was negatively correlated with resident root biomass, and positively correlated with soil nitrate concentrations, suggesting that competition for nitrogen limited invader success. Resident root biomass increased and soil nitrate concentrations decreased with the presence of C4 grasses and also across the diversity gradient, suggesting that diverse plots are more competitive because of the presence of C4 grasses. In addition to this evidence for a sampling effect, we also found evidence for a complementarity effect. Specifically, the percentage of plots that had lower invader biomass than did the best resident monoculture (i.e. that had invader underyielding) increased across the species richness gradient. This pattern cannot be explained by a sampling effect and is a unique signature of complementarity effects. Our results demonstrate the importance of multiple mechanisms by which diversity can increase invasion resistance.
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Plant diversity soil microbial communities and ecosystem function are there any links
Ecology, 2003Co-Authors: William E Holmes, Aaron D. Peacock, David C White, David TilmanAbstract:A current debate in ecology centers on the extent to which ecosystem function depends on biodiversity. Here, we provide evidence from a long-term field manipulation of Plant diversity that soil microbial communities, and the key ecosystem processes that they mediate, are significantly altered by Plant species richness. After seven years of Plant growth, we determined the composition and function of soil microbial communities beneath Experimental Plant diversity treatments containing 1-16 species. Microbial community bio- mass, respiration, and fungal abundance significantly increased with greater Plant diversity, as did N mineralization rates. However, changes in microbial community biomass, activity, and composition largely resulted from the higher levels of Plant production associated with greater diversity, rather than from Plant diversity per se. Nonetheless, greater Plant pro- duction could not explain more rapid N mineralization, indicating that Plant diversity affected this microbial process, which controls rates of ecosystem N cycling. Greater N availability probably contributed to the positive relationship between Plant diversity and productivity in the N-limited soils of our experiment, suggesting that Plant-microbe in- teractions in soil are an integral component of Plant diversity's influence on ecosystem
Bernhard Schmid - One of the best experts on this subject based on the ideXlab platform.
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co occurrence history increases ecosystem stability and resilience in Experimental Plant communities
Ecology, 2021Co-Authors: Bernhard Schmid, Nico Eisenhauer, Sofia J Van Moorsel, Terhi Hahl, Owen L Petchey, Anne Ebeling, Cameron WaggAbstract:Understanding factors that maintain ecosystem stability is critical in the face of environmental change. Experiments simulating species loss from grassland have shown that losing biodiversity decreases ecosystem stability. However, as the originally sown Experimental communities with reduced biodiversity develop, Plant evolutionary processes or the assembly of interacting soil organisms may allow ecosystems to increase stability over time. We explored such effects in a long‐term grassland biodiversity experiment with Plant communities with either a history of co‐occurrence (selected communities) or no such history (naive communities) over a 4‐yr period in which a major flood disturbance occurred. Comparing communities of identical species composition, we found that selected communities had temporally more stable biomass than naive communities, especially at low species richness. Furthermore, selected communities showed greater biomass recovery after flooding, resulting in more stable post‐flood productivity. In contrast to a previous study, the positive diversity–stability relationship was maintained after the flooding. Our results were consistent across three soil treatments simulating the presence or absence of co‐selected microbial communities. We suggest that prolonged exposure of Plant populations to a particular community context and abiotic site conditions can increase ecosystem temporal stability and resilience due to short‐term evolution. A history of co‐occurrence can in part compensate for species loss, as can high Plant diversity in part compensate for the missing opportunity of such adaptive adjustments.
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species evenness and productivity in Experimental Plant communities
Oikos, 2004Co-Authors: Christa P H Mulder, E Bazeleywhite, Panayiotis G Dimitrakopoulos, Andy Hector, Michael Schererlorenzen, Bernhard SchmidAbstract:In nature, Plant biomass is not evenly distributed across species, and naturally uncommon species may differ from common species in the probability of loss from the community. Understanding relationships between evenness and productivity is therefore critical to understanding changes in ecosystem functioning as species are lost from communities. We examined data from a large multi-site grassland experiment (BIODEPTH) for relationships between evenness of species composition (proportional abundance of biomass) and total biomass of communities. For plots which started with the same and even species composition, but which diverged in evenness over time, those with lower evenness had a significantly greater biomass. The relationship between evenness and biomass across all plots was also negative. However, for communities where the most common species represented one of the three largest species in monoculture at that site (inclusion of a large dominant species), the relationship was neutral. Path analyses indicated that three paths contributed to this negative relationship. First, higher species richness decreased evenness, but increased biomass (primarily through an increase in maximum Plant size). Contrary to predictions, maximum Plant size had either no effect on evenness, or a positive effect (in year 3 plots with a large dominant species), thereby reducing this relationship. In year 2, large variation among species in Plant size (as measured in monoculture) both decreased evenness and increased biomass, thus increasing the strength of the negative relationship between evenness and biomass. However, the former effect was only found in plots with a large dominant species, the latter only in plots without a large dominant species. When species richness, maximum Plant size, and variation in size were accounted for, in year 2 evenness positively affected biomass in plots that included a large dominant species. Our results are consistent with the view that naturally uncommon species may be unaffected by (or even benefit from) the presence of a large naturally common species, and that uncommon Plants may have little ability to increase productivity in the absence of such a species. We conclude that the observed negative relationship between evenness and biomass resulted from multiple direct and indirect effects, the relative strength of which depended in part on the presence of large dominant species.
Frank Berendse - One of the best experts on this subject based on the ideXlab platform.
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Diversity reduces invasibility in Experimental Plant communities the role of Plant species
Ecology Letters, 2003Co-Authors: Gerlinde B. De Deyn, Frank BerendseAbstract:Several studies have presented Experimental evidence that diversity reduces invasibility in grassland communities. The interpretation of these results has been disputed recently and it was proposed that sampling effects were responsible for the observed decrease of invasibility with diversity. The experiments performed to date were not designed to adequately separate sampling from diversity effects. Using the establishment of native Plant species in Experimental Plant communities as a model of invasibility, we show that the number of invaders decreased with increasing diversity. When the presence of particular species is included, their effects are dominant. Centaurea jacea showed a strong effect at low diversity, whereas Leucanthemum vulgare showed a very strong negative impact at each diversity level. The negative effect of the latter might be related to root-feeding nematodes that showed far higher abundance in plots with Leucanthemum. However, diversity remained a significant factor in determining the number of invading species and the numbers of an abundant invader.
Jason D Fridley - One of the best experts on this subject based on the ideXlab platform.
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resource availability dominates and alters the relationship between species diversity and ecosystem productivity in Experimental Plant communities
Oecologia, 2002Co-Authors: Jason D FridleyAbstract:Experimental evidence that Plant species diversity has positive effects on biomass production appears to conflict with correlations of species diversity and standing biomass in natural communities. This may be due to the confounding effects of a third variable, resource availability, which has strong control over both diversity and productivity in natural systems and may conceal any positive effects of diversity on productivity. To test this hypothesis, I independently manipulated resource availability (soil fertility) and sown species diversity in a field experiment and measured their individual and interactive effects on productivity. Although fertility was a far stronger predictor of productivity than diversity, the effect of diversity on productivity significantly increased with fertility. Relative yield analyses indicated that Plant mixtures of high fertility treatments significantly "overyielded," or were more productive than expected based on monoculture yields of component species. In contrast, Plant mixtures of low fertility treatments had significantly lower-than-expected yields. The effect of diversity on productivity was also driven by sampling effects, where more species-rich mixtures were more likely to include particularly productive species. Unexpectedly, the strength of sampling effects was largely insensitive to fertility, although the particular species most responsible for sampling effects did change with fertility. These results suggest that positive effects of species diversity on ecosystem productivity in natural systems are likely to be masked by variation in environmental factors among habitats.
Peter Stoll - One of the best experts on this subject based on the ideXlab platform.
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Effects of spatial pattern and relatedness in an Experimental Plant community
Evolutionary Ecology, 2008Co-Authors: Ursula Monzeglio, Peter StollAbstract:Many Plant species show limited dispersal resulting in spatial and genetic substructures within populations. Consequently, neighbours are often related between each other, resulting in sibling competition. Using seed families of the annuals Capsella bursa-pastoris and Stachys annua we investigated effects of spatial pattern (i.e. random versus aggregated) on total and individual performance at the level of species and seed families under field conditions. At the level of species, we expected that inferior competitors increase, while superior competitors decrease their performance within neighbourhoods of conspecifics. Thus, we expected a species by spatial pattern interaction. Sibling competition, however, might reduce the performance of competitors, when genetically related, rather than non-related individuals are competing. Therefore, aggregations at the level of seed families could decrease the performance of competitors. Alternatively, if the opposite outcome would be observed, kin selection might be hypothesized to have occurred in the past. Because heavy seeds are expected to disperse less than light seeds, we further hypothesized that kin selection might be more likely to occur in superior competitors with heavy, locally dispersed seeds (e.g. Stachys ) compared to inferior competitors with light, more distantly dispersed seeds (e.g. Capsella ). We found a significant species by spatial pattern interaction. Indeed, the inferior competitor, Capsella , showed increased reproductive biomass production in aggregated compared to random patterns. Whereas, the performance of the superior competitor, Stachys , was to some extent decreased by intraspecific aggregation. Although statistically not significant, effects of intrafamily aggregations tended to be rather negative in Capsella but positive in Stachys . Our results confirmed that spatial patterns affect growth and reproduction of Plant species promoting coexistence in Plant communities. Although, we could not provide strong evidence for sibling competition or kin selection, our results suggested that competition among relatives was more severe for Capsella (lighter seeds) compared to Stachys (heavier seeds).
