Abstract. Long-term, high-resolution canopy cover data are essential for understanding grassland ecosystem dynamics and informing sustainable management. However, existing products are largely limited to coarse spatial resolutions, constraining their utility for high-precision, large-scale analyses. In this study, we collected over 16,000 drone image tiles (30 m × 30 m) from 2,144 sites across China and developed a machine learning model to produce a spatially seamless, 30 m annual dataset of national grassland canopy cover from 1990 to 2023 by integrating drone and Landsat-series imagery. The model achieves high predictive accuracy (R2 = 0.73, RMSE = 18.4 %) and robust temporal transferability (R2 = 0.68, RMSE = 20.6 %). Comparisons with existing large-scale products demonstrated significantly improved accuracy and reduced residual artifacts, underscoring the robustness of our approach across diverse grassland types and time periods. Spatiotemporal analysis indicated a multi-decadal mean canopy cover of 43.80 ± 18.69 % across China’s grasslands. Over the 34-year period, 41.76 % of grasslands exhibited significant increases, 57.16 % showed nonsignificant change, and 1.08 % experienced significant declines. Climatic factors—including drought, precipitation, and temperature—emerged as the dominant drivers of canopy cover dynamics at the national scale, although their effects exhibited pronounced spatial heterogeneity. In contrast, anthropogenic pressures played a secondary role overall but could override climatic influences at local scales. Collectively, these findings, together with the long-term, high-resolution canopy cover dataset developed in this study, provide an essential basis for advancing the understanding of grassland ecosystem dynamics and for supporting evidence-based conservation and sustainable management strategies, particularly under intensifying climate change and increasing frequency of extreme events. The national grassland canopy cover dataset generated in this study is archived on Zenodo and can be freely downloaded from https://doi.org/10.5281/zenodo.20301123 (Jiang et al., 2026).

Non-structural carbohydrates (NSCs) serve as key metabolic substrates and carbon reserves in plants, playing a central role in regulating vegetation carbon dynamics. Despite their importance, the global distribution and underlying drivers of NSC variations remain uncertain. We compiled a database consisting of 29,386 field measurements on NSC concentrations during the growing season, covering 1,016 sites and 2,041 species, to examine organ-specific NSC patterns and disentangle the relative contributions of environmental conditions and evolutionary history. Leaf NSC concentrations increase with latitude, whereas stem and root NSC concentrations decline, linked primarily to water availability, temperature and solar radiation. The spatial contrast reflects differentiated source-sink controls on NSC storage along environmental gradients. In contrast, NSC concentrations increase with evolutionary divergence time in leaves, but decline in stems and roots. Crucially, evolutionary history explains a larger portion (55.9-77.1%) of global NSC variations across organs, surpassing contemporary environmental controls. These findings reveal the organ-specific disparity in NSC storage and underscore the central role of evolutionary history in shaping global NSC variability, with important implications for plant carbon balance and vegetation carbon modelling.

High-altitude arid regions are characterized by concurrent water scarcity, low temperatures, and intense solar radiation. However, the adaptive mechanisms of desert shrubs to these combined stressors remain poorly understood. To address this gap, we integrated large-scale field surveys with laboratory measurements of eight stem and leaf anatomical traits across six common desert shrub species in the Qaidam Basin. Principal component analysis (PCA) revealed two primary axes of trait variation. The first principal component (PC1) characterized a trade-off between leaf protective traits (e.g., cuticle and epidermal thickness) and stem hydraulic-storage traits (e.g., central cylinder, xylem, and pith diameters). The second principal component (PC2) was primarily loaded by stem cortex thickness, representing a physiological buffering mechanism. Based on PC1, species were categorized into two distinct strategic groups. Group A prioritized investment in stem conductive and storage tissues, enhancing hydraulic safety under hotter, high-evaporative demand conditions. Conversely, Group B exhibited reinforced leaf protective structures, consistent with tolerance to high radiation and low-temperature stress at higher elevations. The environmental gradients were the primary drivers of this divergence: Group A was associated with aridity, whereas Group B was correlated with elevation. Our findings demonstrate that desert shrubs in the Qaidam Basin have employed diverse adaptive strategies via the modulation of organ-specific anatomical traits to mitigate environmental stressors. These findings offer valuable insights into plant adaptive mechanisms, with implications for predicting vegetation responses and informing ecological restoration in high-altitude arid ecosystems.

Leaf traits influence biotic interactions and ecosystem functions in forests. However, biogeographic drivers of leaf traits remain highly uncertain, limiting their integration into global vegetation models. Using a global dataset of forest plots, we show that community canopy leaf traits align along three dimensions: leaf economy, leaf density, and nitrogen-to-phosphorus (N:P) ratio. Changes in these trait dimensions across forest communities were driven by different variables: leaf economy was primarily shaped by the proportion of deciduous trees, leaf density by soil available P and temperature, and leaf N:P ratio by temperature. These three leaf trait dimensions together explained 60.2% of the variation in ecosystem-scale forest maximum photosynthesis, with the leaf N:P ratio showing the strongest association, followed by the dimensions of leaf economy and leaf density. Forests with moderate leaf N:P ratios and more acquisitive traits had higher photosynthesis than other forests. Our findings highlight the potential of community canopy leaf traits in predicting biogeographic variation in ecosystem-scale forest functioning.

Anthropogenic nitrogen (N) and phosphorus (P) inputs have significant effects on plant community composition and diversity in forest ecosystems. Compared to canopy layers, understory communities are more sensitive to exogenous nutrient inputs. Although some experimental evidence exists on the effects of N addition on understory communities, knowledge about the impacts of P addition and its interaction with N, as well as the underlying mechanisms, remains limited. Here, we conducted two nutrient manipulation experiments in tropical primary and secondary montane rainforests, and synthesized 33 peer-reviewed studies to evaluate the impacts of N and P enrichments on species richness, density, and cover of understory plants in forests. Integrated evidence from field experiments and meta-analyses consistently demonstrated that nutrient enrichment with N, P, or both significantly reduced the species richness, density, and cover of understory plant communities. The negative impacts intensified with experimental duration and addition rate. Mechanistically, alteration in soil conditions including excessive accumulations of N and P as well as N-induced soil acidification mainly caused the loss of understory plant species. Our study underscores the negative influences of anthropogenic nutrient inputs on understory community diversity and coverage, thereby altering forest structure and functioning in the future.

Bamboo forests substantially contribute to the biogeochemical cycling of carbon (C) and help mitigate climate change. Moso bamboo (Phyllostachys edulis), which occupies the largest bamboo forest area globally, is widely distributed across China. However, the C stocks of these forests and their controlling factors remain poorly quantified due to a lack of large-scale field data. Here, we conducted a nationwide survey of 322 plots and 1,245 soil samples throughout the full distribution range of moso bamboo forests in China. We estimated a total ecosystem C stock of 511.0 +/- 9.9 Tg C, with 29% stored in vegetation and 71% in soil (0-50 cm). Vegetation C density was weakly influenced by climate but increased under moderate human disturbance. Soil C density was shaped by both climate and human activity: higher temperature, precipitation, and wetness index promoted soil C accumulation, whereas intensive disturbance indirectly reduced soil C by decreasing soil moisture and nitrogen content. These findings suggest that increasing drought and intensified human activity may reduce soil C sequestration in bamboo ecosystems. Our study provides a new field-based estimate of C stocks in China's bamboo forests and offers insights to improve biogeochemical models and inform C sink management.

Plant-insect herbivore interactions are essential in shaping forest ecosystem health. The resource availability hypothesis (RAH) and the leaf economics spectrum (LES) theory predict that species in high-resource environments tend to adopt a 'fast' strategy but are more susceptible to herbivory. However, this contradicts the reports of increased insect herbivory in the context of global drought intensification and hinders accurate prediction about how different plant species respond to herbivorous insect feeding. To fill this knowledge gap, we conducted an observational study in two temperate forests dominated by Quercus mongolica and Betula platyphylla in eastern China to compare their leaf herbivory patterns and explore possible mechanisms. We measured three leaf herbivory proxies (consumed leaf area, percent consumed and herbivory frequency), some leaf traits (leaf area [LA], specific leaf area [SLA], leaf water content [LWC], leaf nitrogen, phosphorus and non-structural carbohydrate contents) and soil properties (pH, soil water content [SWC], soil organic carbon content, soil nitrogen and phosphorus contents). We found that Q. mongolica, growing in poorer soil environments with lower water and nutrient contents, experienced higher leaf herbivory than B. platyphylla. Regarding leaf traits, Q. mongolica had a higher LA and non-structural carbohydrate content, but lower SLA, leaf nutrient and water contents, than B. platyphylla. At the leaf level, LA, rather than SLA, of both tree species was positively correlated with leaf herbivory. At the tree level, species-specific patterns emerged, that is, leaf herbivory of B. platyphylla was positively related to LA and negatively related to leaf nitrogen and water contents and soil phosphorus content, whereas that of Q. mongolica was only positively affected by soil phosphorus content. These findings challenge the predictions of RAH and LES theory, as Q. mongolica that grows in resource-poor soil environments with a conservative strategy suffers higher leaf herbivory than B. platyphylla, shedding some light on the proverb that trouble follows the needy. Moreover, water-related factors (i.e. LWC and SWC) and LA showed an important effect on driving interspecific and intraspecific leaf herbivory variations here, implying that climate-induced droughts may exacerbate herbivore pressure in temperate forests.Read the free Plain Language Summary for this article on the Journal blog.

China represents a significant global hotspot for species in the family Fagaceae, which are widely distributed across the country and play a crucial role in various ecological and social systems. As the global cliamte is changing rapidly, predicting the future distribution and richness of these species in China holds substantial importance. This study presents the first national-scale assessment of the future distribution of 243 Fagaceae species in China, utilizing ensemble species distribution models (SDMs) for the 2050s and 2070s under various climate change scenarios. The SDM projections indicate notable changes in the distribution of Fagaceae species, characterizing with an overall decline in the distribution area, an upward migration in elevation and a northeastward shift in their range. These changes are expected to significantly alter the spatial pattern of species richness, creating possible refugia in the southwestern mountainous regions and the western Qinling Mountains. We further revealed that a considerable amount of China's natural reserves will show decreased richness of Fagaceae under climate change. Our study systematically evaluates the impact of future climate change on the distribution of Fagaceae species in China, potentially helpful for conservation planning of these species in China. (sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic);(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)2050,2070(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)243(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Ecological stoichiometry in the plant-soil-microbial systems is crucial for regulating nutrient flow and sustaining ecosystem functions in forests. However, how rising atmospheric nitrogen (N) deposition induced by human activities impacts the stoichiometric relationships across ecosystem compartments remains poorly understood. We therefore conducted a 13-year N-addition experiment across eight forests from tropical to boreal zones in China, to assess the shifts in carbon:nitrogen:phosphorus (C:N:P) stoichiometry across live plant tissues, detritus, soil, and microbes. The N addition significantly elevated N concentrations in green leaves (+7.2% to 10.1%), twigs (+8.4%), fine roots (+20.2%), and leaf litter (+5.9%), while decreasing microbial N (-16.0%) and P concentrations (-20.2% to - 12.1%) across compartments. These changes triggered compartment-specific responses, with greater stoichiometric variability in plants than in soils, particularly in high-latitude forests. However, N addition did not significantly alter the intrinsic scaling relationships of P concentrations and N:P ratios among compartments or the N-P scaling patterns within individual compartments. Our findings provide new insights into the resilience and complexity of nutrient regulation in forests under chronic N deposition, with important implications for predicting long-term ecosystem responses and developing sustainable nutrient management strategies.

Mixed deciduous-evergreen needleleaf forests (MNs) are widely distributed in the northern hemisphere. However, the issue whether MNs are climax forests or transitional ones is remaining uncertain. Based on 1318 plots surveyed across China, we aim to clarify this issue by comparing the differences in species composition and environmental characteristics between MNs and other two similar coniferous forest types, i.e., evergreen needleleaf forests and deciduous needleleaf forests at both the national and regional scales. The results indicate that MNs have distinct floristic composition and diagnostic species in most cases. Specifically, species richness and the importance value of rhizomatous herbs in MNs are significantly higher than in evergreen needleleaf forests observed at the national scale and in some cases at the regional scales. In addition, the importance value of tussock herbs in MNs tends to be lower than in deciduous needleleaf forests, but woody species abundance in MNs is significantly higher than in deciduous needleleaf forests observed at the national scale and in some cases at the regional scales. With respect to environmental characteristics, MNs tend to preferentially grow in the habitats with lower precipitation, moderate temperature, semi-shady or semi-sunny, and lower to mid-slopes in nature compared to other two similar coniferous forest types. Our findings thus indicated that MNs represent a climax forest type rather than a transition between two vegetation types only.

Tropical forest soils are susceptible to acidification owing to high weathering rates and low buffering capacity. Nutrient additions, particularly nitrogen (N) and phosphorus (P) inputs, can alter soil acidity; however, their long-term effects on the dynamics and underlying mechanisms of soil pH in tropical rainforests are not well understood. Here, we conducted two 13-year N and P fertilization experiments in primary and secondary tropical montane rainforests in Hainan, China. Results showed that long-term high-N addition reduced soil pH, and the effects increased with the rate and duration of N addition in both rainforests. The P-limited primary rainforest was more susceptible to N-induced soil acidification than the N-limited secondary rainforest with higher stand density during the experimental periods. Moreover, the depletion of base cations (primarily Ca2+) and the generation of exchangeable H+ were the main drivers of N-induced soil acidification. However, low- and medium-N additions, single P addition, and combined N and P addition did not significantly change soil pH or cation concentrations in both forests. These findings suggest that elevated soil N availability induced by long-term fertilization may alter soil cation composition, thus leading to soil acidification and impacting ecosystem functions in tropical forests.

The distribution and assembly of plant species is a fundamental ecological question. Understanding how various drivers of community assembly vary along elevational gradients and differentially affect species occurrence versus abundance is critically important. Using an advanced tool, the joint species distribution model (JSDM), we aim to investigate shifts in the relative importance of climatic and non-climatic effects on forest community assembly along large elevational gradients, and to compare the elevational trends of these effects on species occurrence and abundance. We documented 243 forest plots, each with a size of 20 x 30 m, along elevational gradients (700-3650 m) of Qinling Mountains, the highest mountain in Central China. We performed JSDMs to quantify the relative importance of climatic and non-climatic effects on species occurrence and abundance along elevational gradients. Climatic and non-climatic effects exhibited distinct elevational trends and differed in their respective influences on species occurrence and abundance. The influence of climate on species abundance increased with elevation, whereas its effect on species occurrence showed a weak decline. At lower elevations, species occurrence was mainly determined by climate, while abundance was affected by both climatic and non-climatic drivers. At higher elevations, climate emerged as the dominant factor affecting both occurrence and abundance. Our study reveals different trends of climate and non-climate effects on species occurrence versus abundance. These findings underscore the importance of jointly considering both types of environmental drivers and both occurrence and abundance, which is critical for predicting community dynamics under climate change and guiding conservation strategies. (sic)(sic):(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)((sic)(sic)(sic)(sic)(sic)(sic)(sic))(sic)(sic)(sic)(sic)(sic)(sic)(700-3650 m)(sic)(sic)(sic)243(sic)(sic)(sic)(sic)(sic)((sic)(sic)(sic)(sic)(sic)20 m x 30 m),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(JSDM)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic);(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

Green stem photosynthesis is well known, but the effect of stem photosynthesis on plant growth and development remains uncertain. In this study, green stems of semiannual Rosa chinensis were subjected to a shading treatment to explore the effect of stem photosynthesis on the growth and biomass accumulation. The results showed that (i) stem photosynthesis affected biomass accumulation and allocation in R. chinensis. The stem shading treatment decreased the biomass of R. chinensis by similar to 18.7%. The proportion of biomass allocated to the stems increased, while the proportion of biomass allocated to the leaves and roots decreased. (2) Stem photosynthesis facilitates an increase in nonstructural carbohydrate concentration, chlorophyll a concentration and chlorophyll a/b of R. chinensis. (3) The net photosynthesis in the stems of R. chinensis was negative, and biomass accumulation was significantly positively correlated with the dark respiration rate in stems, indicating that stem photosynthesis fixed CO2 released internally by respiration. This study reveals that stem photosynthesis in R. chinensis enhances biomass accumulation by promoting chlorophyll fluorescence and dark respiration rates in the stems. Furthermore, stem photosynthesis contributes to the balanced allocation of biomass by enhancing the proportional distribution of biomass to leaves and roots.

Plant-soil interactions are crucial in shaping ecosystem functions and have been widely studied. However, the relationships between plant traits and soil microbial communities remain unclear. In this study, we collected data on plants, soils, and microbes from 54 sites in temperate grasslands to investigate how soil microbial biomass and diversity vary with climate, soil nutrients, and plant diversity and leaf traits at a regional scale. The examined factors accounted for 53

Human activities alter disturbance regimes, influencing forest structure and ecosystem carbon. Identifying and quantifying natural and anthropogenic disturbances at fine spatial scales are critical to assessing the role of forests in climate change mitigation. This study investigated disturbance history and carbon storage in human-impacted forests and open ecosystems at elevations of 2000-4200 m in northwestern Yunnan, China. We established 50 sampling plots along the four due orientations of a mountain peak. Using tree rings, fire scars, satellite imagery, official records, and interviews, we reconstructed historical disturbances and identified fires, logging events, landslides, and icy precipitation since the 1950s. We analyzed the impact of disturbance history and topography on ecosystem carbon storage, including pools in soil (0-30 cm), woody debris, and non-woody and woody plants. Disturbances since the 1950s were largely driven by anthropogenic activities over time, along with climate and topography. Fires and logging were common near settlements in Pinus yunnanensis forests at lower elevations, while landslides primarily occurred in steep areas of Abies georgei forests and logged areas within broadleaf mixed forests. Icy precipitation was more frequent above 3500 m on the south and west slopes in A. georgei forests. Non-forest areas at higher elevations had a mean ecosystem carbon (including soil carbon down to 30 cm) density of 146 Mg C ha-1, while forest areas averaged 270 Mg C ha-1. Fire negatively impacted soil, woody plants, and overall ecosystem carbon, whereas logging impacts were limited to woody plants and overall ecosystem carbon. Carbon storage in woody plants and total ecosystem carbon followed a hump-shaped pattern with elevation, peaking near 3200 m. Our study links disturbance histories to spatial variation in carbon pools. This study helps improve carbon management and conserve biodiversity in human-modified forests and presents a multi-source approach that could be used in other human-impacted forests.

Green stem photosynthesis is well known, but the effect of stem photosynthesis on plant growth and development remains uncertain. In this study, green stems of semiannual Rosa chinensis were subjected to a shading treatment to explore the effect of stem photosynthesis on the growth and biomass accumulation. The results showed that (1) Stem photosynthesis affected biomass accumulation and allocation in R. chinensis. The stem shading treatment decreased the biomass of R. chinensis by approximately 18.7%. The proportion of biomass allocated to the stems increased while the proportion of biomass allocated to the leaves and roots decreased. (2) Stem photosynthesis facilitates an increase in nonstructural carbohydrate concentration, chlorophyll a concentration and chlorophyll a/b of R. chinensis. (3) The net photosynthesis in the stems of R. chinensis was negative, and biomass accumulation was significantly positively correlated with the dark respiration rate in stems, indicating that stem photosynthesis fixed CO2 released internally by respiration. This study reveals that stem photosynthesis in R. chinensis enhances biomass accumulation by promoting chlorophyll fluorescence and dark respiration rates in the stems. Furthermore, stem photosynthesis contributes to the balanced allocation of biomass by enhancing the proportional distribution of biomass to leaves and roots.

Tropical rainforests on low-phosphorus soils are highly biodiverse and productive, playing a crucial role in climate change mitigation. However, the degree of phosphorus limitation and potential adaptation mechanisms of tropical rainforests remain unclear. Here, we conducted a decade-long field experiment with nitrogen (N) and phosphorus (P) additions in primary and secondary tropical rainforests. We investigated growth responses of 2012 individual trees and explored how litter, soil, and microbes contribute to maintaining P availability for plants. We found that the P addition alone enhanced tree growth in both rainforests. Adding P (alone or with N) increased the average leaf P concentrations of eight species but reduced P resorption efficiency (PRE), soil phosphatase activity, and fungal diversity in the two forests. Phosphorus addition triggered divergent responses in fungal community composition across both forests: characterized by an enrichment of ectomycorrhizal fungi (EMF) and a depletion of arbuscular mycorrhizal fungi (AMF). Crucially, EMF functional guilds differentiated: short-distance exploration types increased significantly, while long-distance types declined. These findings reveal that tropical rainforests adapt to P limitation through microbially mediated strategies: enhanced soil phosphatase activity for organic P mineralization and shifts toward EMF functional groups specialized in P acquisition. Reduced PRE indicates lower reliance on internal P recycling under elevated P availability. This study underscores the importance of P availability in shaping the productivity of tropical rainforests, providing critical insights into their adaptive responses to nutrient limitations.

The conifer forest in southwest China is the key habitat for the giant panda (Ailuropoda melanoleuca) and vital for ecosystem services, but is being degraded by livestock grazing. Grazing influences soil environment and biota through top-down control of aboveground-belowground systems. Despite its significance, the effects of livestock grazing on soil environment and microbial communities in forest ecosystems, particularly in biodiversity hotspots, remain underexplored compared to aboveground system. Using fence experiments and structural equation models, our study identified three key mechanisms through which livestock grazing affects soil environments and microbial dynamics in a primary coniferous forest in southwest China. Livestock grazing boosted soil bacterial diversity, and altered soil properties (reducing soil organic matter and increasing pH), which indirectly suppressed bacterial diversity and diminished the prevalence of the dominant fungal group, Basidiomycota. The decreased dominance of Basidiomycota fostered greater diversity, with increased representation of subordinate groups like Ascomycota and Actinobacteria, which suggested a significant “dominance effect” within soil microbial communities. The rapid response of soil environments and microbial diversity to short-term fencing experiments suggests that rotational grazing management could be beneficial for soil ecosystem restoration. We recommend incorporating soil and microbial indicators, such as Basidiomycota’s relative abundance, into conservation monitoring to track soil recovery. Short-term monitoring of these indicators allows for timely assessment of grazing management, enabling quick strategic adjustments to prevent irreversible long-term degradation. Continued monitoring of microbial shifts in relation to functions like forest growth and litter decomposition is essential for understanding the ecological consequences of livestock disturbance.