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Purpose: Understanding the impact of neighbor tree diversity on soil biodiversity at the individual tree scale and clarifying which facets of neighbor tree diversity have a decisive impact on soil biodiversity. Methods: We collected and identified soil nematodes underneath 256 individual trees of 16 species at four species-richness levels (1, 2, 4, 8 species) in a large tree diversity experiment in southeast China. We analyzed how the taxonomic, phylogenetic, and functional diversity of the nematode community were influenced by neighbor tree diversity. Results: Our analyses showed that nematode alpha diversity at the individual tree scale decreased with increasing neighbor tree richness while beta diversity increased at taxonomic, phylogenetic, and functional levels. Nematode alpha diversity at the plot scale increased with increasing neighbor tree richness. Secondly, we found that reducing redundant species and increasing distinct species led to the differentiation of nematode communities under different individual trees in high-richness plots. Finally, our data revealed that the functional diversity of the neighbor tree community had the largest effects on the diversity of the local nematode community. Conclusion: Our study emphasizes that there is a significant influence from neighboring trees, mainly the functional traits of the trees, even though they are spaced at distances multitudes greater than the distance over which soil nematodes can move. Hence it is important to consider these broader spatial aspects when examining the plant and soil biotic interactions. [ABSTRACT FROM AUTHOR]

Understanding contributions of different environmental drivers to the structure and function of river biota is critical for biodiversity and environmental conservation. Yet, there is no consensus on which drivers have the greatest impact on fish diversity, especially in watersheds disturbed by multiple human activities. Fish taxonomic, phylogenetic, and functional diversity at both alpha and beta dimensions and their environmental drivers were studied in a total of 84 river sites from three watersheds, Huai River watershed (HRW), Sui River watershed (SRW), and Yishusi River watershed (YRW) in the Eastern Huai River Basin of China. Results showed that rivers in the three watersheds had no significant difference in both taxonomic and functional alpha diversity. Rivers in the HRW had significantly higher phylogenetic alpha diversity. For taxonomic and phylogenetic beta diversity, the overall beta diversity and turnover component were significant higher in the HRW. For functional beta diversity, the overall beta diversity was significantly lower in the HRW. Multiple linear regression (MLR) and redundancy analysis (RDA) showed that local (e.g., nutrients, dissolved oxygen, river width, transparency), regional (e.g., wetland), climate (e.g., temperature), and spatial variables structured alpha and beta fish diversity. Variation partitioning analysis indicated that the pure contributions of local and spatial variables were more important than that of climate and regional variables, which suggested that spatial effects and local environmental filtering were the main factors driving the beta diversity of fish assemblages in these rivers. The current study highlights the importance of considering multidimensional diversity and multiple environmental factors for conserving river fishes. [ABSTRACT FROM AUTHOR]

Information on temporal dynamics of phytoplankton communities and their responses to environmental factors can provide insights into mechanisms driving succession of phytoplankton communities that is useful in programs to manage and or remediate undesirable assemblages. Populations of phytoplankton can be controlled by bottom-up factors such as nutrients and temperature or top-down such as predation by zooplankton. Traditionally, taxonomic diversity based on morphologies has been the measure used for analysis of responses to environmental factors. Recently, according to functional groupings, including functional groups (FG), morpho-FG (MFG), and morphology-based FG (MBFG), functional diversity has been used to represent functional aspects of phytoplankton communities. However, to what extent these taxonomic and functional groupings are congruent at seasonal time-scales and the main environmental factors, which drive succession, have remained less studied. Here, we analyzed absolute and relative proportions of a phytoplankton community during a 3-year period in Lake Erhai, a eutrophic highland lake in China. Alpha diversity and beta diversity, as measured by Shannon-Wiener and Bray-Curtis indices of taxonomic grouping and three functional groupings (FG, MFG, and MBFG) were applied to investigate environmental factors determining diversity. Significant, positive relationships were observed between taxonomic diversity and functional diversity that were strongly linked through seasons. In order to exclude the influence of dominant species' tolerance to extreme environments, the dominant species were excluded one by one, and the results showed that residual communities still exhibited similar patterns of succession. This synchronous temporal pattern was not principally driven by the dominant genera (Microcystis , Psephonema , and Mougeotia). Instead, the entire phytoplankton community assemblages were important in the pattern. Most diversity indices of taxonomic and functional groupings were significantly correlated with solar irradiance, but not nutrient concentrations. Because the lake is eutrophic and there were already sufficient nutrients available, additional nutrients had little effect on seasonal taxonomic and functional diversity of phytoplankton in Lake Erhai. [ABSTRACT FROM AUTHOR]

China's five largest freshwater lakes (Poyang, Dongting, Taihu, Hongze, and Chaohu) are all located in lowland regions and differ greatly in lake morphology, hydrology, and water chemistry. However, basic knowledge of diversity patterns and factors driving macroinvertebrate community structure is lacking. We analyzed the composition and diversity of benthic macroinvertebrates and evaluated the roles of environmental factors and dispersal processes in determining beta diversity at both the lake and regional scales. The two Yangtze-connected lakes (i.e., Lakes Poyang and Dongting) were highest in taxonomic diversity. Differences in taxonomic composition were evident among the five lakes, with the two Yangtze-connected lakes dominated by bivalves and/or gastropods, while Lake Taihu showed great changes in taxonomic composition among sites in accordance with its high habitat heterogeneity. Lake Hongze was dominated by polychaetes, crustaceans, and bivalves. The eutrophic-hypertrophic Lake Chaohu was exclusively dominated by chironomids and oligochaetes. At the lake scale, total γ-diversity was mainly attributed to β -diversity (among sites) ranging from 57.9 to 87.6%. The total γ-diversity at the regional scale was primarily related to higher β-diversity, with β and β (among lakes) accounting for 30.4 and 58.8% of total taxa richness, respectively. Environmental conditions appear to be important in structuring benthic macroinvertebrate communities at both the lake and regional scale. Dispersal does not appear to affect distribution of macroinvertebrates at the lake scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Patterns and driving factors of fish biodiversity in metacommunities were quantified. • Almost all indices of alpha and beta diversity decreased during the 1980 s-2010 s. • Land use contributed more to biodiversity decline than other stressors. Understanding patterns and driving factors of freshwater fish biodiversity in metacommunities is essential for biological conservation but rarely studied in regions experiencing rapid land use changes. We examined changes of both alpha and beta fish diversities in taxonomic, functional, and phylogenetic facets during the 1980 s to 2010 s, and quantified contributions from natural and human drivers in lakes located in China's fastest economic development region. Results showed that almost all indices of alpha and beta diversity decreased through time. For alpha diversity, taxonomic and functional richness declined by 13 to 15%. Rheophilic and piscivorous fish species declined by 50 and 36%, respectively. For beta diversity, the decline of overall functional (-31%) diversity was greater than taxonomic (-17%) and phylogenetic (-19%) diversity. The decline of multiple facets of beta diversity indicated that fish communities in these lakes have homogenized through time. Land use (i.e., increased urban land and aquaculture ponds), hydrology (i.e., increased water level), climate (i.e., increased air temperature), and fishing (i.e., increased lake fishery catch) factors all made significant contributions to both alpha and beta fish diversity decline in multiple facets. The overall contribution from land use to the decline of multidimensional fish diversity was greater than those of other stressors. While attention should be given to both local human disturbance and regional climate factors, in regions experiencing rapid economic development and land use changes, local disturbances should be considered as a priority in biodiversity management plans. [ABSTRACT FROM AUTHOR]

• Minor road redevelopment affects the alpha and beta diversity of bird communities. • Functional diversity is the most sensitive index to minor road redevelopment. • The negative impacts were weaker than that of continuous-use roads. • Minor road redevelopment negatively affected the recovery process of avian diversity. • Even minor road redevelopment warrants careful environmental impact assessment. Although the effects of major roads and highways on biodiversity have received considerable attention, there is a lack of research considering how smaller and less-used roads might also impact wildlife, especially during the initial re-used development phase of abandoned roads, despite these minor roads being much more extensive and pervasive. Here, we examined how even minor redevelopment of former-abandoned logging roads can impact bird community alpha and beta diversity indices at the taxonomic, functional, and phylogenetic levels in a biodiversity conservation hotspot in central China. The minor redevelopment (i.e., re-paved) of former-abandoned roads generally reduced bird alpha and beta diversity compared to undeveloped abandoned roads, especially at the functional level. Compared with continuous-use roads, minor road redevelopment shows only a slight impact on avian diversity. Notably, compared to old-growth forest reference stands and undeveloped abandoned roads, minor road redevelopments have negative effects on the recovery process of avian diversity. Furthermore, the structure and composition of the high tree layer significantly affected avian functional and phylogenetic diversity, and low shrub layer vegetation mainly influenced taxonomic and phylogenetic diversity. To mitigate the effects of minor forest logging roads on avian biodiversity in priority biodiversity conservation areas, we propose the following: (1) roads that have fallen into disuse should be allowed and encouraged to re-naturalise; (2) roads should only be paved, and cleared back as strictly necessary, allowing grassy or gravel roads to suffice where possible; and (3) if road development is necessary, key umbrella tree species should be planted deliberately to support maximal community diversity and to maintain ecosystem functions and processes. [ABSTRACT FROM AUTHOR]

• Soil microbial diversity decreased along a natural aridity gradient. • Bacteria changed their proportion to adapted to environmental changes. • Fungi changed their rare taxa in response to environmental change. • Soil C:N, salinity and regional temperature regulate microbial community. • Soil C:N directly, and SPEI indirectly influence soil microbial diversity. Environmental aridity is increasing in several regions around the globe due to climate change. However, little is known about microbial diversity and community responses to aridity along grassland-to-desert gradients. We investigated soil bacterial and fungal diversity and composition, and associated environmental factors along an aridity gradient across grassland (G), desert-grassland (DG) and desert (D) in Inner Mongolia, Northern China. The results indicate that soil microbial diversity decreased significantly from G and DG to D. Bacteria were mostly dominated by the universal phyla Proteobacteria, Actinobacteria, Bacteroidetes and Acidobacteria. Fungal communities were dominated only by Ascomycota. Most bacterial species (58.7–69.1%) were found in all habitats with significant differences among the three vegetation types, while most soil fungal species occupied small geographic areas. Soil bacterial communities adapted to environmental changes through changes in proportions of their taxa, while fungi changed their rare taxa in response to the differences in local environments. Canonical correspondence analysis (CCA) indicated that soil C:N, salinity and regional temperature were the most important factors regulating microbial community composition. Structural equation models (SEM) revealed that C:N was the most important factor directly influencing soil microbial diversity, and SPEI was the most important factor indirectly influencing soil microbial diversity in the Mongolian desert-grassland ecosystem. Our results provide evidence that soil bacterial and fungal communities respond differently to the changes in the biotic and abiotic factors, reflecting different adaptive strategies for coping with climate change in desert grassland ecosystems. [ABSTRACT FROM AUTHOR]