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The quantification of plant diversity–productivity relationships is essential for accurate productivity assessments. Global change drivers are altering resource availability and biodiversity. However, the extent to which multiple attributes of diversity (species, functions) buffer community productivity in response to the resource availability changes and the potential driver mechanisms of the diversity‐productivity relationship still needs to be the consensus. We investigated the ephemeral plant diversity–productivity relationships of different attributes along a precipitation gradient in the Gurbantunggut Desert, China. To evaluate the potential mechanisms by which diversity and functional composition affect aboveground productivity (niche complementarity and selection effect). Our results showed that (1) the variance of species richness (SR), Rao's quadratic entropy (RaoQ), community‐weighted mean of height (CWMH), and community‐weighted mean of leaf phosphorus concentration (CWMP) was larger among sites (variation between different sites) than subplots (variation between different subplots). Among subplots, the variance of community‐weighted mean of specific leaf area (CWMSLA), community‐weighted mean of leaf carbon concentration (CWMC), and community‐weighted mean of leaf nitrogen concentration (CWMN) was larger than the sites. (2) SR, RaoQ, CWMC, CWMN, CWMH, pH, and mean annual precipitation (MAP) collectively influenced the accumulation of aboveground biomass (AGB). (3) Species diversity and MAP have strongly affected AGB and accounted for 50% and 42%. The study confirms that SR is the optimal predictor of biomass in ephemeral plants. Complementation effects may be the primary mechanism explaining the relationship between biodiversity and productivity in the Gurbantunggut Desert, and thus the effect of plant diversity cannot be downplayed. [ABSTRACT FROM AUTHOR]

Forest aboveground biomass (AGB) plays an important role in regulating the global carbon cycle and is thus an essential component of ecosystem functioning. In the relationships between biodiversity and ecosystem functioning (BEF), studies have shown that many biotic factors (e.g., species, functional traits, and large trees) and abiotic factors have significant impacts on AGB. However, the relative strength of these affecting factors remains unclear. In this study, we analyzed woody plants (diameter at breast height [DBH] ≥ 1 cm) within a 1.6 ha plot in an old-growth subtropical natural forest in southern China. We used structural equation models to test the effects of tree diversity (species, phylogenetic, functional, and size inequality), functional composition, large trees, and environmental factors (topography, soil nutrients, and understory light) on AGB. Our results indicated that size inequality, the community-weighted mean of maximum DBH (CWM_MDBH), and large trees had significant, positive effects on AGB (p < 0.001), while lower soil phosphorus content was found to promote an increase in AGB. Furthermore, large trees, which were mostly composed of dominant tree species, were the main driver of AGB, and the effect of functional composition (e.g., CWM_MDBH) on AGB was substantially reduced by large trees. We argue that the selection effect plays a key role in regulating BEF relationships in subtropical natural forests and conclude that retaining large-diameter trees and dominant species, along with sustaining a complex stand structure, are key measures for improving productivity. [ABSTRACT FROM AUTHOR]

Question: Environmental filtering plays an important role in plant community assembly. To what extent does the broad‐scale environment influence the functional composition of woody plants in China's forests? Is there stronger trait convergence under harsher environmental conditions? Location: China. Methods: We characterized community traits and their relationships to climate and soil, using a data set with 1312 plots of tree communities composed of 1591 tree species and 10 functional traits across China. Using quadratic models, we explored how community traits change with different environmental factors. Results: Trait spectra at the species level and the community level were significantly correlated, and the first two principal components captured 74.5% of the variation in community‐weighted mean traits. The trait spectra showed a clear elevational pattern and varied along climate and soil gradients. Compared with random expectations, the multi‐trait functional diversity showed a divergence pattern on poor soils at the plot scale. Conclusions: Two well‐known dimensions, the leaf economics spectrum and size‐related spectrum, could be extended from the species level to the community level. Environment, especially climate conditions, drives the trait spectra and their elevational patterns at the broad scale, indicating environmental filtering might shape the trait composition of tree communities in China. However, stronger environmental filtering does not occur under harsher environmental conditions. [ABSTRACT FROM AUTHOR]

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Addressing the escalating challenges of climate change necessitates a comprehensive understanding of the factors influencing carbon sequestration rates (CSRs) in forest ecosystems. Although the impact of various biotic factors, environmental, and anthropogenic factors on CSRs over different time scales is well recognized, their precise roles remain poorly defined. This study aims to clarify the mechanistic relationships between CSRs and these factors in large-scale natural temperate forests in northeastern China. We employed linear mixed-effects models and piecewise structural equation models were to analyze data from 310 vegetation plots, assessing the effects of biotic factors (including multidimensional diversity, structural diversity, and community-weighted mean (CWM) trait values) and abiotic factors (climate, topography, and anthropogenic disturbances) across different forest types and successional stages. Our analysis tested a series of hypotheses to identify the principal drivers of forest CSRs. The results indicate that while functional composition and standard environmental factors such as mean annual temperature and slope are significant, their influence is markedly less than that of biodiversity (encompassing multidimensional and structural diversity) and anthropogenic disturbance (as measured by the Human Modification Index). These findings support the dominance of the niche complementarity theory and the moderate disturbance hypothesis, with their importance increasing over time. Furthermore, this study advocates for forest management strategies that are specifically tailored to the unique characteristics of mixed and dense forests at different stages of succession. By elucidating the complex relationships between ecological variables and CSRs, our findings provide critical insights for the development of effective strategies aimed at optimizing forest carbon sequestration. This study underscores the necessity of integrating sustainable forest management with the conservation of ecological biodiversity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To address environmental variations in metabolic composition of straw-decomposing bacterial community, we performed a 16-week field-based buried straw experiment at three experimental sites across subtropical China. We found that, although the taxonomic composition was highly variable, the functional composition was conserved across all experimental sites. This was likely because stochastic dispersal limitation governed the high taxonomic turnover of the community, leading to high environmental variability, whereas metabolic niche selection resulted in stable functional composition and lower redundancy. The integrated knowledge on the response of functional and taxonomic composition to environmental variability might help to understand microbial-driven straw decomposition at a large scale, considering the significance of microbial functional and taxonomic composition to biogeochemical cycling. [ABSTRACT FROM AUTHOR]

Purpose: Glaciers of the Tianshan Mountains have been geographically isolated for a long time with little human interference. This study aimed to understand the viral community structures and their ecological functions in a unique glacier soil. Materials and methods: The abundances of purified virus particles and bacteria in the glacier soil were examined using epifluorescence microscopy and quantitative PCR of the 16S rRNA gene, respectively. Metagenomic analysis was employed to investigate the taxonomic and functional compositions as well as the phylogenetic relationship of the functional genes of the viruses in the glacier soil. Results and discussion: A total of eight double-stranded DNA (dsDNA) virus families were identified in the glacier soil, with Siphoviridae, Podoviridae, and Myoviridae being the more abundant families. The diverse dsDNA viruses and few ssDNA and other types of viruses formed the unique community structure of viruses in the Tianshan Mountains glacier soil. The functional genes identified from the virome mainly belonged to phage-related proteins. The phage terminase of Caudovirales presented high diversity, and its amino acid sequences were different from those in other environments. Conclusions: The results showed a unique viral diversity and taxonomic composition in the glacier soil, which suggests the significant ecological role of Caudovirales in this environment. [ABSTRACT FROM AUTHOR]

Increased nitrogen (N) deposition may have profound effects on forest ecosystems. However, information on the impacts of elevated N deposition on belowground soil seed bank in forests is lacking. In a field experiment, we added N at 50 and 25 kg N ha−1 year−1 to the canopy (CAN50 and CAN25) and to the understory (UAN50 and UAN25), to determine the effects of N deposition on soil seed bank structure and composition in a subtropical evergreen broadleaved forest. A total of 1545 seedlings belonging to 37 species emerged from the 10 cm-depth soil samples. After 6 years of N addition, soil seed bank density significantly increased at the depth of 0–10 cm under CAN50 treatment relative to the control. N addition did not significantly affect species richness, the Simpson index, Shannon–Wiener index, or Pielou index of the soil seed banks. Seed bank density and species richness were positively correlated with soil organic matter content. For the whole 0–10 cm soil layer, the percentage of total seed abundance and total species richness represented by tree species among the N-addition treatments was ≤9.3% and ≤16.1%, respectively. Soil seed bank composition was similar among UAN25, UAN50, and the control, but canopy N addition and especially CAN50 altered the species composition of the seed bank. Overall, our results indicate that artificial canopy N deposition at 50 kg N ha−1 year−1 but not understory N addition tends to promote seed storage and to change species composition in the soil seed bank. Because of the dominance of shrubs and herbs in the soil seed bank, the potential to regenerate tree species from the soil seed bank is limited in the subtropical evergreen broadleaved forest. [ABSTRACT FROM AUTHOR]

The tissues of marine invertebrates are colonized by species-rich microbial communities. The dysbiosis of host's microbiota is tightly associated with the invertebrate diseases. Yesso scallop (Patinopecten yessoensis), one of the most important maricultured scallops in northern China, has recently suffered massive summer mortalities, which causes huge production losses. The knowledge about the interactions between the Yesso scallop and its microbiota is important to develop the strategy for the disease prevention and control. In the present study, the bacterial communities in hemolymph, intestine, mantle and adductor muscle were compared between the healthy and diseased Yesso scallop based on the high-throughput sequencing of 16S rRNA gene. The results indicated obvious difference of the composition rather than the diversity of the bacterial communities between the healthy and diseased Yesso scallop. Vibrio, Francisella and Photobacterium were found to overgrow and dominate in the mantle, adductor muscle and intestine of the diseased scallops, respectively. The prediction of bacterial community metagenomes and the variations of KEGG pathways revealed that the proportions of the pathways related with neurodegenerative diseases and carbohydrate metabolism both increased significantly in the mantle and hemolymph of the diseased scallops. The abundance of the metabolism pathways including carbohydrate metabolism, lipid metabolism and amino acid metabolism decreased significantly in the intestine of diseased scallops. The results suggested that the changes of bacterial communities might be closely associated with the Yesso scallop's disease, which was helpful for further investigation of the pathogenesis as well as prevention and control of the disease in Yesso scallop. [ABSTRACT FROM AUTHOR]

The biodiversity value of river-oxbow lake systems in high plateau peatland has been little recognized, and there are many gaps in our understanding of their ecology. In this study, we investigated the river-oxbow lake system of the Bai River basin, the main tributary of the Yellow River Source in the Zoige wetland from 2015 to 2016, in attempt to show how the environmental variations, especially hydrological connectivity and macrophyte biomass in the river-oxbow lake system influenced macroinvertebrates. Habitat patches were investigated in 11 river cross-sections and 18 oxbow lakes in the Bai River basin. Through hierarchical clustering and non-metric multidimensional scaling, four main types of habitats were identified in the river-oxbow lake system in the plateau: sand-bed river, cobble-bed river, sparse-macrophyte oxbow lake, and luxuriant-macrophyte oxbow lake. The luxuriant-macrophyte oxbows were characterized by high dissolved oxygen concentrations, alkalinity, and higher macroinvertebrate richness, density, biomass, and the Improved Shannon-Wiener Index in comparison to the other habitat types. Additionally, influential patterns of environmental variables on macroinvertebrates were analyzed using redundancy analysis. Lasso regression models were established to describe how macroinvertebrate density responded to macrophyte biomass and other variables, and how macrophyte biomass responded to hydrological connectivity and oxbow size. It was revealed that reduced hydrological connectivity and reduced oxbow size played important roles in increasing the biomass of submerged macrophyte, and dense macrophyte was directly responsible for the high biodiversity of macroinvertebrates. Different from the commonly believed unimodal influential pattern that medium hydrological connectivity supports the highest biodiversity in oxbow lakes reported in previous studies, macroinvertebrates in the high plateau river-oxbow lake systems benefited from low connectivity and reduced size. Oxbow lakes, especially those covered with luxuriant macrophytes, diversified the macroinvertebrate assemblages and enhanced primary consumer biomass at the regional scale., (Copyright © 2018 Elsevier B.V. All rights reserved.)