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Elucidating mechanisms underlying community assembly and biodiversity patterns is central to ecology and evolution. Genome size (GS) has long been hypothesized to potentially affect species' capacity to tolerate environmental stress and might therefore help drive community assembly. However, its role in driving β‐diversity (i.e., spatial variability in species composition) remains unclear. We measured GS for 161 plant species and community composition across 52 sites spanning a 3200‐km transect in the temperate grasslands of China. By correlating the turnover of species composition with environmental dissimilarity, we found that resource filtering (i.e., environmental dissimilarity that includes precipitation, and soil nitrogen and phosphorus concentrations) affected β‐diversity patterns of large‐GS species more than small‐GS species. By contrast, geographical distance explained more variation of β‐diversity for small‐GS than for large‐GS species. In a 10‐year experiment manipulating levels of water, nitrogen, and phosphorus, adding resources increased plant biomass in species with large GS, suggesting that large‐GS species are more sensitive to the changes in resource availability. These findings highlight the role of GS in driving community assembly and predicting species responses to global change. [ABSTRACT FROM AUTHOR]

Summary: The continuing nitrogen (N) deposition observed worldwide alters ecosystem nutrient cycling and ecosystem functioning. Litter decomposition is a key process contributing to these changes, but the numerous mechanisms for altered decomposition remain poorly identified.We assessed these different mechanisms with a decomposition experiment using litter from four abundant species (Achnatherum sibiricum, Agropyron cristatum, Leymus chinensis and Stipa grandis) and litter mixtures representing treatment‐specific community composition in a semi‐arid grassland under long‐term simulation of six different rates of N deposition.Decomposition increased consistently with increasing rates of N addition in all litter types. Higher soil manganese (Mn) availability, which apparently was a consequence of N addition‐induced lower soil pH, was the most important factor for faster decomposition. Soil C : N ratios were lower with N addition that subsequently led to markedly higher bacterial to fungal ratios, which also stimulated litter decomposition.Several factors contributed jointly to higher rates of litter decomposition in response to N deposition. Shifts in plant species composition and litter quality played a minor role compared to N‐driven reductions in soil pH and C : N, which increased soil Mn availability and altered microbial community structure. The soil‐driven effect on decomposition reported here may have long‐lasting impacts on nutrient cycling, soil organic matter dynamics and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Background and aims: Variations in plant nitrogen (N) and phosphorus (P) concentrations and ratios have great implications for primary productivity and nutrient cycling. Here, we reported their changes at functional group and community levels along an aridity gradient. Methods: We carried out a field investigation and set up 26 sampling sites along a transect in the drylands of northern China to examine the responses of plant nutrient status to increasing aridity and the relationships between plant and soil nutrients. Results: The responses of N and P concentrations to increasing aridity differed between woody (sub-) shrubs and herbaceous species (including annual/biennial forbs and grasses, perennial forbs and perennial grasses). Nitrogen and P concentrations of shrubs decreased while those of herbs generally increased with increasing aridity. Plant N:P ratios increased significantly with increasing aridity for the plant functional groups and at the community level. At both organizational levels, nutrient concentrations in plants were negatively related to those in soils. Conclusion: Our results indicated that the responses of plant nutrition to aridity were dependent on plant functional group. Plant growth appeared increasingly limited by P, and plant and soil nutrients become increasingly decoupled at large spatial scale with increasing aridity. [ABSTRACT FROM AUTHOR]

• Soil microbial community diversity and composition showed intra-annual variation. • Nitrogen addition significantly reduced alpha-diversity of both bacteria and fungi communities across all months. • Mowing did not affect soil microbial community diversity and composition. • Mowing did not mediate the effects of N addition in soil microbial community. Atmospheric nitrogen (N) deposition has important effects on soil microbial community diversity and composition. While it is well-known that mowing, a widely used grassland management strategy, could mediate the impacts of N enrichment on macro-organism community composition, much less known is the intra-annual variation of soil microbial community and their responses to N deposition and mowing. Here, we examined the responses of soil bacteria and fungi communities to N deposition and mowing in four months of different seasons in a semiarid grassland in northern China. Nitrogen addition significantly reduced alpha-diversity and changed the community composition of both bacteria and fungi communities across generally all months, possibly due to N-induced soil acidification. Mowing did not affect soil microbial community diversity and did not mediate the impacts of N addition. Soil microbial community diversity and composition significantly varied across different months. Such temporal variation of soil microbial community composition was much greater than the variation resulting from N addition and mowing. Our results suggest that the negative impacts of N enrichment on soil bacteria and fungi diversity are temporally consistent and are unaffected by plant biomass removal. [ABSTRACT FROM AUTHOR]