Composition of ‘fast–slow’ traits drives avian community stability over North America

Population trends are more strongly linked to environmental change and species traits in birds than mammals

Changes in land use and climate directly impact species populations. Species with divergent characteristics may respond differently to these changes. Therefore, understanding species' responses to environmental changes is fundamental for alleviating biodiversity loss. However, the relationships between land use changes, climate changes, species' intrinsic traits and population changes at different spatial scales have not been tested. In this study, we analysed the effects of land use and climate changes from different time periods and species traits on the population change rates of 2195 bird and mammal populations in 577 species recorded in the Living Planet Database at global, tropical and temperate scales. We hypothesized that both bird and mammal populations will decline owing to climate and land use changes, especially phylogenetically young and small-bodied species. We found that bird population trends were more closely related to environmental changes and phylogenetic age than those of mammals at global and temperate scales. Mammal population trends were not significantly correlated with land use or climate changes but were with longevity at global and temperate scales. Given the divergent responses of bird and mammal populations to these explanatory variables, different conservation strategies should be considered for these taxa and for different regions.

Smaller microorganisms outcompete larger ones in resistance and functional effects under disturbed agricultural ecosystems

Body size is a key ecological trait of soil microorganisms related to their adaptation to environmental changes. In this study, we reveal that the smaller microorganisms show stronger community resistance than larger organisms in both maize and rice soil. Compared with larger organisms, smaller microorganisms have higher diversity and broader niche breadth to deploy survival strategies, because of which they are less affected by environmental selection and thus survive in complex and various kinds of environments. In addition, the strong correlation between smaller microorganisms and ecosystem functions reflects their greater metabolic flexibility and illustrates their significant roles in adaptation to continuously changing environments. This research highlights the importance of body size in maintaining stability of the soil microbiome and forecasting agroecosystem dynamics under environmental disturbances.

Urban landscape organization is associated with species-specific traits in European birds

Urbanization is one of the main current drivers of the global biodiversity loss. Cities are usually developed in a gradient between land-sharing (low density housing with small and fragmented green areas) and land-sparing areas (high density housing with large and non-fragmented green patches) depending on the spatial organization of urban attributes. Previous studies have indicated differences in biodiversity between these two urban development types, but mechanisms underlying these differences are inadequately understood. In this context, the landscape features of each urban development type may select for organisms with specific traits. To analyze it, we quantified birds in 9 European cities during the breeding and wintering season, collected species-specific traits and performed Bayesian comparative analyses. We found that birds living in land-sparing areas had a higher reproductive investment and a higher nesting specialization than birds living in land-sharing areas during the breeding season. Typical birds from land-sparing urban areas during winter are fast-lived species. Our results indicate that urban development type could have an important role selecting animal traits and provides useful information on how to build more biodiversity-friendly cities.

Influence of Last Glacial Maximum legacies on functional diversity and community assembly of extant Chinese terrestrial vertebrates

Contemporary biodiversity patterns are shaped by not only modern climate but also factors such as past climate fluctuations. Investigating the relative degree of paleoclimate legacy could help us understand the formation of current biodiversity patterns. However, an assessment of this issue in China is lacking. Here, we investigated the phylogenetic structure and functional diversity patterns of Chinese terrestrial vertebrates. We found that Southern China harbored higher functional richness, while Northern and Western China were more phylogenetically clustered with higher functional divergence and evenness, indicating environmental filtering effects. Moreover, we found that drastic Last Glacial Maximum climate changes were positively related to phylogenetic clustering, lower functional richness, and higher functional divergence and evenness, although this effect varied among different taxonomic groups. We further found that mammal communities experiencing more drastic Last Glacial Maximum temperature changes were characterized by "faster" life-history trait values. Our findings provide new evidence of the paleoclimate change legacies influencing contemporary biodiversity patterns that will help guide national-level conservation plans.

Environmental factors indirectly reduce phytoplankton community stability via functional diversity

The biodiversity-stability relationship is a fundamental subject of ecological research. Considerable evidence demonstrates that biodiversity can either increase or decrease stability. Most relevant research mainly focuses on grassland and forest ecosystems. The biodiversity-stability relationship in aquatic ecosystems and the underlying mechanisms remain poorly understood. To fill the gap, we conducted a year-long study on the phytoplankton of reservoir ecosystems in the Xiangxi Bay of Three Gorges Reservoir (TGR) to test the following hypotheses: (H1) phytoplankton species richness and functional diversity directly reduce phytoplankton community stability in reservoir ecosystems; (H2) nutrient enrichment and water temperature increasing directly reduce phytoplankton community stability; and (H3) nutrients and water temperature indirectly reduce phytoplankton community stability via biodiversity. The structural equation model (SEM) found that functional diversity (community-weighted means of traits and functional divergence) had significant negative correlations with phytoplankton community stability (p < 0.05), while the species diversity had no significant correlation with phytoplankton community stability (p > 0.05). This finding partially supported the hypothesis H1, which suggested that the functional diversity had a closer tie with stability than the species diversity. SEM did not find any direct effect of environmental factors on phytoplankton community stability, which rejected our hypothesis H2. Instead, SEM found that water temperature and phosphate decreased phytoplankton community stability by increasing the first principal component of the community-weighted means of traits (CWM_PC1), which supported hypothesis H3. Further analysis showed that the increased water temperature and phosphate concentration can promote “r-strategists” species (larger CWM_PC1), which are less resistant to environmental disturbances, therefore decreasing the phytoplankton community stability. Our study highlights the importance of functional diversity in maintaining the relationship between biodiversity and stability in the phytoplankton community, which may provide a mechanistic understanding of the biodiversity-stability relationships in aquatic ecosystems.