Search for: All records

Abstract Global changes such as nitrogen (N) enrichment and elevated carbon dioxide (CO₂) are known to exacerbate biodiversity loss in grassland ecosystems. They do so by modifying processes whose strength may vary at different spatial scales. Yet, whether and how global changes impact plant diversity at different spatial scales remains elusive.We collected data on species presence and cover at a high resolution in the third decade of a long‐term temperate grassland biodiversity—global change experiment. Based on the data, we constructed species—area relationships across three spatial orders of magnitude (from 0.01 to 3.24 m²) and compared them for the different global change treatments.We found that N enrichment, both under ambient and elevated CO₂levels, decreased species richness across almost all spatial scales, with proportional decreases being largest at the smallest spatial scales. Elevated CO₂also reduced richness at both ambient and enriched N supply rates but did so proportionally across all spatial scales. Suppression of diversity was stronger at all scales for diversity indices that include relative abundances than for species richness. Taken together, these results suggest that CO₂and N are re‐organizing this grassland system by increasingly favouring, at fine scales, a small subset of dominant species.Synthesis: Our results highlight the role of spatial scales in influencing biodiversity loss, especially when it is driven by anthropogenic resource changes that might influence species interactions differently across spatial scales. 

ABSTRACT Elements are the basic substances that make up living organisms, and the element composition in plants quantitatively reflect the adaptation of plants to environment. However, the drivers that constitute the species‐specific plant elementome, as well as the bivariate bioelemental correlations in determining the stability of different bioelements are yet unclear. Based on 1058 leaf observations of 84 plant species from 232 wetlands across large environmental gradients, we found that bioelements with higher concentration were more stable and evolutionary constrained. We proposed a stability of well‐coordinated elements hypothesis, suggesting that bioelements that coordinate well in driving certain physiological functions constrain each other, thus maintaining relatively stable ratios in plants. In contrast, those functionally independent bioelements fluctuate greatly with environmental nutrient availability. Cold and saline stresses decreased plant stoichiometric network connectivity, complexity, and stability. Our research filled the gap in study of wetland plant elementome, and provided new evidences of plant–environment interactions in regions sensitive to climate change. 

Abstract Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity.