Microbial functional trait dynamics during seedling development-a critical yet underexplored driver of forest ecosystem establish, develop, and stability-remain poorly understood. We investigated bacterial genomic traits dynamics in subtropical Pinus massoniana seedlings over a growing season. Leaf-associated bacteria showed minimal temporal shifts, whereas root-associated bacteria exhibited pronounced trends: average genome size increased (independent of nitrogen addition), whereas ribosomal RNA operon copy number (RRN) declined under ambient nitrogen, indicating a transition from fast-growing to slow-growing strategies. These trajectories reflect the differential turnover of later, nitrogen-insensitive taxa (e.g. large-genome, low-RRN Bradyrhizobium) relative to earlier, nitrogen-sensitive taxa (e.g. small-genome, high-RRN Herbaspirillum) during colonization and establishment from an aerial source onto a developing host. Additionally, we detected a discrepancy between the temporal dynamics of predicted nitrogen fixation potential and quantitative real-time PCR-based nifH quantification, underscoring the need for caution when interpreting prediction-based functional potentials. These findings identify trait-mediated assembly as a key driver of early root microbiome dynamics in pine seedlings and highlight the need for temporally resolved, ground-truthed functional inference when predicting ecosystem processes.

Fish functional response to conservation measures such as fishing bans is very important for lake biodiversity conservation but remains less studied. We conducted a 6-year fish community investigation in Luoma Lake of the Huai River Basin in China, including three years (2018–2020) before and three years (2021–2023) after a full fishing ban (i.e., complete removal of fishing pressure). Taxonomic and functional diversity indices, including species richness, Shannon and Simpson diversity index, Pielou’s evenness, functional richness (FRic), functional evenness (FEve), and functional dispersion (FDis), were used to assess community-level changes. Community-weighted mean (CWM) values were calculated from 12 functional traits, and R-mode linked to Q-mode (RLQ) analysis combined with the fourth-corner test was conducted to link traits to environmental gradients. We found no significant change in fish abundance and taxonomic diversity, but fish biomass and functional richness increased significantly after the fishing ban. Non-metric multidimensional scaling (NMDS) and similarity percentage (SIMPER) analysis indicated that the fish community underwent significant compositional changes following the fishing ban. Trait–environment analysis showed that age at first maturity, mouth position, body shape, feeding habit, and life history strategy were significantly associated with environmental gradients. These results suggest that the fishing ban promoted early functional recovery and ecological reorganization processes of the fish community, highlighting the functional mechanisms underlying assemblage restructuring.

Global warming is increasing the frequency and intensity of climate extremes. Forests may buffer climate extremes by creating their own attenuated microclimate below their canopy, which maintains forest functioning and biodiversity. However, the effect of tree diversity on temperature buffering in forests is largely unexplored. Here, we show that tree species richness increases forest temperature buffering across temporal scales over six years in a large-scale tree diversity experiment covering a species richness gradient of 1 to 24 tree species. We found that species richness strengthened the cooling of hot and the insulation against cold daily and monthly air temperatures and temperature extremes. This buffering effect of tree species richness was mediated by enhanced canopy density and structural diversity in species-rich stands. Safeguarding and planting diverse forests may thus mitigate negative effects of global warming and climate extremes on below-canopy ecosystem functions and communities.

Latitudinal patterns of tree β-diversity reveal important insights into the biogeographical processes that influence forest ecosystems. Although previous studies have extensively documented β-diversity within relatively small spatial extents, the potential drivers of β-diversity along latitudinal gradients are still not well understood at larger spatial extents. In this study, we determined whether tree β-diversity is correlated with latitude in forests of southeastern China, and if so, what ecological processes contribute to these patterns of tree β-diversity. We specifically aimed to disentangle the relative contributions from interspecific aggregation and environmental filtering across various spatial extents. We delineated regional communities comprising multiple nearby national forest inventory (NFI) plots around random focal plots. The number of NFI plots in a regional community served as a surrogate for spatial extent. We also used a null model to simulate randomly assembled communities and quantify the deviation (β-deviation) between observed and expected β-diversity. We found that β-diversity decreased along a latitudinal gradient and that this pattern was clearer at larger spatial extents. In addition, latitudinal patterns of β-deviation were explained by the degree of species spatial aggregation. We also identified environmental factors that drive β-deviation in these forests, including precipitation, seasonality, and temperature variation. At larger spatial extents, these environmental variables explained up to 84% of the β-deviation. Our results reinforce that ecological processes are scale-dependent and collectively contribute to the β-gradient in subtropical forests. We recommend that conservation efforts maintain diverse forests and heterogeneous environments at multiple spatial extents to mitigate the adverse effects of climate change.

Biodiversity-ecosystem functioning relationships have been extensively studied, particularly within the primary layers of producers in terrestrial ecosystems. In multilayer ecosystems such as forests, the contribution of diversity in the secondary layer, i.e. shrubs, to ecosystem functioning is still largely unknown. Here we used 11-year growth data from a forest biodiversity experiment with factorially crossed manipulations of tree and shrub species richness to assess their effects on forest productivity. We found that shrub species richness had positive effects on tree and total woody biomass (sum of tree and shrub biomass), with effect sizes similar in magnitude to those of tree species richness: increasing tree or shrub species richness from two to eight promoted tree biomass by 73.1% or 53.9% and total woody biomass by 46.7% or 37.1%, respectively. The positive effects of tree or shrub species richness on tree and total woody biomass became larger over time. Shrub biomass was reduced by tree species richness. The effects of tree and shrub species richness can be partially explained by their increased functional diversity. Our study provides the first evidence that understory diversity can significantly increase forest productivity and should not be neglected in forest restoration to promote ecosystem functioning.

Insect herbivores are integral to the functioning of forest ecosystems. However, increasing herbivore outbreaks highlight the need to understand the factors driving the spatial and temporal stability of herbivore communities. While the longer term consequences of climatic fluctuations are well established in this context, the role of local-scale interactions between herbivores, their host communities, and local microclimates in influencing herbivore stability remains unclear. In this study, we investigated the relative importance of host tree species richness, functional diversity, trait composition, tree growth dynamics, and climate in driving herbivore spatiotemporal stability and the resulting patterns in abundance and diversity. We focused on Lepidoptera caterpillars as very diverse and functionally highly relevant herbivores in forest ecosystems. Tree species richness promoted mean caterpillar abundance, species richness, and phylogenetic diversity by positively affecting their temporal and spatial stability. These effects were mostly direct but counteracted by largely independent and overall negative effects of tree functional diversity, tree growth stability, and microclimate temperature stability. The strength and direction of these effects varied across seasons, reflecting shifts in environmental conditions and herbivore species turnover. The effects of tree diversity on caterpillar communities were related to compositional changes through distinct pathways by reducing taxonomic beta diversity and thus enhancing species richness stability and by increasing phylogenetic beta diversity which may promote asynchrony among distantly related species. Crucially, our findings suggest that tree diversity buffers herbivore communities against climate fluctuations by enhancing their spatiotemporal stability. In consequence, ongoing biodiversity loss may lead to greater fluctuations in herbivore populations and an increased risk of outbreaks. Our study provides novel insights into the mechanisms underlying bottom-up regulation of herbivores, emphasizing the critical role of tree diversity in maintaining stable herbivore communities in a changing climate.

IntroductionEthylene response factors (ERF) were important for plant growth, hormone signaling, fruit ripening and stress response. Despite the wide identification of ERF family members in various species, limited information is available regarding this family in Akebia trifoliata.MethodsThe APETALA2/ethylene response factor genes in A. trifoliata were identified and analyzed using bioinformatic approaches and AtrERF001 was verified to be involved in fruit ripening by experiments.ResultsTherefore, 131 APETALA2/ethylene response factor genes were identified from the A. trifoliata genome. Gene structures, motif compositions, tandem duplication events and promoter structure of ERF genes were characterized, providing insights into the molecular basis underlying the discrepant functions of ERF genes within each evolutionary branch. Expression patterns under ethylene and 1-MCP treatments of these ERF genes were further analyzed using real-time PCR (RT-qPCR), revealing that 9 key ERF genes are closely associated with fruit ripening. A co-expression regulatory network analysis indicated that AtrERF001 was one of the hub gene. AtrERF001 was found to localize in nucleus by subcellular localization analysis. Overexpression of AtrERF001 in Akebia trifoliata and tomato fruit resulted in early fruit ripening. The expression levels of AtrERF001, AtrACO and AtrPE in overexpression fruits were increased by about 30-fold, 5-fold and 1-fold, respectively, compared with the control, whereas silencing of AtrERF001 in A. trifoliata by virus induced gene silencing showed opposite trends. Moreover, RT-qPCR experiments showed that the expression of AtrERF001, AtrACO and :AtrPE in AtrERF001 overexpression tomato fruits at red-ripe stage were significantly increased compared with the control fruits, indicating that AtrERF001 may play an important role in regulating fruit ripening.DiscussionOur results provide new insights into the underlying regulatory mechanisms of the AP2/ERF family during fruit ripening.

Tree diversity can promote both predator abundance and diversity. However, whether this translates into increased predation and top-down control of herbivores across predator taxonomic groups and contrasting environmental conditions remains unresolved. We used a global network of tree diversity experiments (TreeDivNet) spread across three continents and three biomes to test the effects of tree species richness on predation across varying climatic conditions of temperature and precipitation. We recorded bird and arthropod predation attempts on plasticine caterpillars in monocultures and tree species mixtures. Both tree species richness and temperature increased predation by birds but not by arthropods. Furthermore, the effects of tree species richness on predation were consistent across the studied climatic gradient. Our findings provide evidence that tree diversity strengthens top-down control of insect herbivores by birds, underscoring the need to implement conservation strategies that safeguard tree diversity to sustain ecosystem services provided by natural enemies in forests.

It is of great significance to accurately assess the carbon sink capacity and trend of forest ecosystems on a regional scale, which is a key step to realizing sustainable forest management and carbon sink. Based on several remote sensing datasets, this study analyzes the dynamic characteristics of forest carbon stock in the Yangtze River Basin and its response to environmental factors using the Mann–Kendall nonparametric test, correlation analysis, and BP neural network during 2005–2020. The results show that forest carbon stock in the Yangtze River Basin shows a fluctuating upward trend, with an average annual growth rate of 0.91%. Forest carbon stock in western high-altitude areas and areas with high human activity in the east showed a downward trend, while the central plains showed a stable growth trend. In the vast plains of the Yangtze River Basin, a suitable drought degree (−0.5 < SPEI < 0.5) is helpful to the accumulation of forest carbon reserves. In the future, rich forest resources should be fully developed to promote synergy between environmental protection and economic development from the perspective of developing green carbon trading, such as the carbon-sink forestry projects of CCER.

Business parks account for 30% of China's total carbon emissions. Exploring emissions reduction approaches for business parks is crucial to achieve a net-zero emissions target, as well as for achieving a representative example for all types of emissions entities. Business parks mainly adopt two types of emissions reduction approaches: energy-saving renovations and purchasing carbon reduction products. However, there are limited studies focusing on the optimal combinations of the two approaches for reaching net-zero emissions and evaluating the cost effectiveness. To find a feasible and quantified way to build net-zero business park, a comprehensive path decision model is proposed. The problem is broken down into two parts: the optimal carbon reduction portfolio and the optimal electricity saving were researched. For the optimal product portfolio, the Markowitz theory is employed to balance the risk of carbon reduction products with the expected cost. In the part of optimal electricity saving, considering a ten-year life cycle, the total cost includes renovation investment, carbon reduction products cost, and cost saving of electricity consumption reduction. Based on the energy consumption, technical, and price data, the combination of energy-saving renovations and carbon reduction products is optimized. The model suggests a business park can save 24% of energy consumption through renovation investment and purchase CCER as 66% of the carbon reduction product portfolio. Taking only purchasing carbon reduction products as a benchmark to assess economic efficiency, implementing an optimized level of energy-saving renovation is found to save 16% of the comprehensive cost for the life cycle required to achieve zero carbon emissions. This model provides a new comprehensive optimization idea that will help future parks make decisions to achieve zero-carbon emission targets.

Litter decomposition is a key ecosystem function in forests and varies in response to a range of climatic, edaphic, and local stand characteristics. Disentangling the relative contribution of these factors is challenging, especially along large environmental gradients. In particular, knowledge of the effect of management options, such as tree planting density and species composition, on litter decomposition would be highly valuable in forestry. In this study, we made use of 15 tree diversity experiments spread over eight countries and three continents within the global TreeDivNet network. We evaluated the effects of overstory composition (tree identity, species/mixture composition and species richness), plantation conditions (density and age), and climate (temperature and precipitation) on mass loss (after 3 months and 1 year) of two standardized litters: high-quality green tea and low-quality rooibos tea. Across continents, we found that early-stage decomposition of the low-quality rooibos tea was influenced locally by overstory tree identity. Mass loss of rooibos litter was higher under young gymnosperm overstories compared to angiosperm overstories, but this trend reversed with age of the experiment. Tree species richness did not influence decomposition and explained almost no variation in our multi-continent dataset. Hence, in the young plantations of our study, overstory composition effects on decomposition were mainly driven by tree species identity on decomposer communities and forest microclimates. After 12 months of incubation, mass loss of the high-quality green tea litter was mainly influenced by temperature whereas the low-quality rooibos tea litter decomposition showed stronger relationships with overstory composition and stand age. Our findings highlight that decomposition dynamics are not only affected by climate but also by management options, via litter quality of the identity of planted trees but also by overstory composition and structure.

Global warming is increasing the frequency and intensity of climate extremes. Forests may buffer such extreme events by creating their own microclimate below their canopy via cooling hot and insulating against cold macroclimate air temperatures. This buffering capacity of forests may be increased by tree diversity and may itself maintain forest functioning and biodiversity. However, despite its relevance for many ecosystem processes, the effect of tree diversity on temperature buffering is largely unexplored. Here, we show that tree species richness consistently increases forest temperature buffering across daily, monthly, and annual scales over six years. This finding is based on data from a large-scale tree diversity experiment covering a species richness gradient of 1 to 24 tree species. We found that species richness strengthened both components of forest temperature buffering: the attenuation of hot and of cold macroclimate air temperatures, with the cooling effect being more pronounced. The buffering effect of tree species richness was mediated by canopy density and structural diversity, assessed as leaf area index and stand structural complexity index, respectively. Safeguarding and planting diverse forests may thus mitigate negative effects of global warming and climate extremes on ecosystem functions and communities below the tree canopy.### Competing Interest StatementThe authors have declared no competing interest.

Extreme climate events constitute a major risk to global food production. Among these, extreme rainfall is often dismissed from historical analyses and future projections, the impacts and mechanisms of which remain poorly understood. Here we used long-term nationwide observations and multi-level rainfall manipulative experiments to explore the magnitude and mechanisms of extreme rainfall impacts on rice yield in China. We find that rice yield reductions due to extreme rainfall were comparable to those induced by extreme heat over the last two decades, reaching 7.6 ± 0.9% (one standard error) according to nationwide observations and 8.1 ± 1.1% according to the crop model incorporating the mechanisms revealed from manipulative experiments. Extreme rainfall reduces rice yield mainly by limiting nitrogen availability for tillering that lowers per-area effective panicles and by exerting physical disturbance on pollination that declines per-panicle filled grains. Considering these mechanisms, we projected ~8% additional yield reduction due to extreme rainfall under warmer climate by the end of the century. These findings demonstrate that it is critical to account for extreme rainfall in food security assessments. Using data from long-term nationwide observations and multi-level rainfall manipulative experiments, this study reveals that rice yield reductions due to extreme rainfall in China were comparable to those induced by extreme heat over the past two decades. Further projections highlight the increasing risk of rice yield reductions induced by extreme rainfall by the end of this century.

Parnassia wightiana Wall. ex Wight & Arn., a perennial herb, is an alpine plant distributed across three biodiversity hotspots in China. This species offers an excellent study system to analyze the distribution pattern and genetic structure of high mountainous plant populations. Three chloroplast DNA (cpDNA) regions (rpl32-trnL, trnL-F, and trnS-G) from 442 individuals of 39 populations and internal transcribed spacers (ITS) from 418 individuals of 38 populations were sequenced and analyzed. We identified a total of 26 haplotypes based on the concatenated sequences of cpDNA and a total of 36 based on ITS sequences. A hierarchical analysis of molecular variance indicated significant phylogeographic structure among populations. Mismatch analysis of multipeak and Tajima's D neutral test demonstrated Parnassia wightiana populations within China had not experienced abrupt expansion recently. The allopatric fragmentation resulted in the geographic isolation due to environmental heterogeneity, producing a high proportion of private haplotypes in the distribution of Parnassia wightiana within China.

Plateau wetlands play an important role in protecting biodiversity and regulating runoff and local climate, especially on the Qinghai-Tibet Plateau. Arbuscular mycorrhizal fungi (AMF) can colonize the roots of wetland plants and affect their ecological function. To investigate AMF colonization of wetland plants on the Qinghai-Tibet Plateau, we conducted a field survey of the SouthTibet River Basin across a sampling distance of > 1 000 km and an elevational range of 4 000-5 000 m. A total of 130 AMF OTUs was detected in sediment samples. In addition, a negative correlation was found between elevation and AMF relative abundance in sediment based on generalized linear mixed model analysis, and AMF colonization also decreased significantly with elevation from 4 046-5 157 m. Structural equation model analysis showed that AMF colonization, relative abundance, and richness in sediments were directly affected by elevation, but not significantly impacted by total phosphorus content in sediments. To the best of our knowledge, this study is the first to investigate AMF colonization in wetland plants on a high-elevation plateau (>4 000 m). Our findings have important implications for understanding the interactions between AMF and Qinghai-Tibet Plateau wetland plants.

Forests are ecosystems critical to understanding the global carbon budget, due to their carbon sequestration potential in both aboveground and belowground compartments, especially in species-rich forests. Soil carbon sequestration is strongly linked to soil microbial communities, and this link is mediated by the tree community, likely due to modifications of microenvironmental conditions (i.e., biotic conditions, soil properties, and microclimate). We studied soil carbon concentration and the soil microbial biomass of 180 local neighborhoods along a gradient of tree species richness ranging from 1 to 16 tree species per plot in a Chinese subtropical forest experiment (BEF-China). Tree productivity and different tree functional traits were measured at the neighborhood level. We tested the effects of tree productivity, functional trait identity, and dissimilarity on soil carbon concentrations, and their mediation by the soil microbial biomass and microenvironmental conditions. Our analyses showed a strong positive correlation between soil microbial biomass and soil carbon concentrations. In addition, soil carbon concentration increased with tree productivity and tree root diameter, while it decreased with litterfall C:N content. Moreover, tree productivity and tree functional traits (e.g., fungal root association and litterfall C:N ratio) modulated microenvironmental conditions with substantial consequences for soil microbial biomass. We also showed that soil history and topography should be considered in future experiments and tree plantations, as soil carbon concentrations were higher at sites where historical (i.e., at the beginning of the experiment) carbon concentrations were high, themselves being strongly affected by the topography. Altogether, these results implied that the quantification of the different soil carbon pools is critical for understanding microbial community-soil carbon stock relationships and their dependence on tree diversity and microenvironmental conditions.

Forest biomass is an important indicator of forest ecosystem productivity, and it plays vital roles in the global carbon cycling, global climate change mitigating, and ecosystem researches. Multiscale, rapid, and accurate extraction of forest biomass information is always a research topic. In this study, comprehensive investigation of a larch (Larix olgensis) plantation was performed using remote sensing and field-based monitoring methods, in combination with LiDAR-based multisource data and machine learning methods. On this basis, a universal, multiscale (single tree, stand, management unit, and region), and unit-high-precision continuous monitoring method was proposed for forest biomass components. The results revealed the following. (1) Airborne LiDAR point cloud variables exhibited significant correlation with the aboveground components (except leaves) and the whole-plant biomass (Radj2 > 0.91), suitable for extraction or estimation of forest parameters such as biomass and stock volume. (2) In terms of biomass monitoring at forest stand and management unit scale, a random forest model performed well in fitting accuracy and generalization ability, whereas a multiple linear regression model produced clearer explanation regarding the biomass of each forest component. (3) Using seasonal phenological characteristics in the study area, larch distribution information was extracted effectively. The overall accuracy reached 90.0%, and the kappa coefficient reached 0.88. (4) A regional-scale forest biomass component estimation model was constructed using a long short-term memory model, which effectively reduced the probability of biomass underestimation while ensuring good estimation accuracy, with R2 exceeding 0.6 for the biomass of the aboveground and whole-plant components. This research provides theoretical support for rapid and accurate acquisition of large-scale forest biomass information.

Reducing carbon emissions and increasing carbon sinks are key strategies to effectively remove greenhouse gases from the atmosphere. Assessing the current carbon emission status and predicting future carbon emission scenarios could help formulate effective regional carbon emission reduction targets. However, it is necessary to enhance the carbon sink capacity of terrestrial ecosystems and improve forest management methods to promote greenhouse gas absorption. In this study, the spatiotemporal characteristics and dynamic evolution of fossil fuel CO2 (FFCO2) emissions in China from 2000 to 2019 were analyzed using the standard deviation ellipse, kernel density of emissions, and Theil index. A backpropagation (BP) neural network optimized with a genetic algorithm (GA) was used to predict FFCO2 emission during 2020-2030. The biomass increment methodology was used to predict the potential carbon sinks generated by Chinese Certified Emission Reduction (CCER) carbon-sink forestry projects during 2020-2030. The results showed that China's FFCO2 emissions exhibited a gradual increasing trend during 2000-2019, with an average annual growth rate of 6.29%. China's FFCO2 emissions show a greater distribution on the southeastern coast than in the northwestern interior. The GA-BP prediction shows that China's FFCO2 emissions will continue to fluctuate and increase between 2020 and 2030. The potential of carbon sinks will be 0.69 x 108 Mg C generated by the CCER carbon-sink forestry projects during 2020-2030, which could offset 0.56% of FFCO2 emissions. In the future, imbalances in regional development should be considered when formulating carbon-reduction strategies. Moreover, using carbon-sink of forestry projects of CCER to balance economic development including poverty eradication and environmental conservation should be considered. Specifically, establishing a methodology of projects for the management of natural forests' carbon-sink will be an important future strategy.

Tree survival affects forest biodiversity, structure and functioning. However, little is known about feedback effects of biodiversity on survival and its dependence on functional traits and interannual climatic variability. With an individual‐based dataset from a large subtropical forest biodiversity experiment, we evaluated how species richness, functional traits and time‐dependent covariates affected annual tree survival rates from age 3–12 (years) after planting 39 species across a diversity gradient from 1 to 2, 4, 8 and 16 tree species. We found that overall survival rates marginally increased with diversity at the plot level, with large variation among plots within diversity levels. Significant variation among species in survival responses to diversity and changes in these responses with age were related to species functional traits and climatic conditions. Generally, survival rates of conservative species (evergreen, late‐successional species with thick leaves and high carbon to nitrogen ratio but low specific leaf area, leaf phosphorus and hydraulic conductivity) increased with diversity, age and yearly precipitation, whereas acquisitive species showed opposite responses. Synthesis. Our results indicate that interactions between diversity, species functional traits and yearly climatic conditions can balance survival among species in diverse forests. Planting mixtures of species that differ in functional traits in afforestation projects may lead to a positive feedback loop where biodiversity maintains biodiversity, together with its previously reported beneficial effects on ecosystem functioning.

Advancing the construction of the proposed Zhe-Gan Canal in China would connect the major water systems of Poyang Lake and Qiantang River, opening up new channels for low-cost freight transportation, guiding industrial trade, and forming a new pattern of inland shipping. Here we analyze the regional environment, resources, and ecology in the proposed development zone of the Zhe-Gan Canal, to assess the potential for ecological protection of the river basin while promoting industrial transfers. We will also explore construction solutions for channel locks, water supply, environmental protection practices, and project investment. Thus, this study aims to give a holistic analysis of the comparative advantages of water transportation and the coordinated development of regional economies with the proposed construction of the Zhe-Gan Canal.