The increasing frequency of drought events and elevated nitrogen (N) deposition both affect plant carbon (C) utilization, but whether their individual and interactive effects promote, inhibit, or have no effect on C uptake and allocation remains unclear. We conducted a meta-analysis using 1247 observations from 84 published articles to assess how N addition and drought jointly affected plant photosynthesis, biomass allocation, and nonstructural carbohydrates (NSC) allocation. Our results showed that N addition overall increased plant net photosynthetic rate (Pn) and biomass accumulation, but decreased whole plant total NSC storage. Conversely, drought overall decreased Pn and biomass accumulation while increased whole plant total NSC storage. N addition significantly increased aboveground biomass allocation, whereas drought significantly reduced leaf biomass (LB). Although N addition and drought did not have significant interaction on Pn, biomass allocation, and NSC allocation in terrestrial plants, their interaction significantly increased the root biomass of evergreen broadleaf plants, the LB of deciduous broadleaf plants, and the root-to-shoot ratio of annual herbs. In conclusion, N addition and drought had opposite effects on C uptake, biomass accumulation, and NSC storage in terrestrial plants. The interaction of N addition and drought on biomass allocation was affected by plant functional types. This study enhances our understanding of plant C utilization strategies under multiple environmental changes.

Accurate spatial distribution of vegetation types is fundamental to understanding ecosystem structure, biodiversity patterns, and environmental responses. However, predicting the distribution of lower-level vegetation classification units such as alliances remains challenging due to limited and uneven sample availability, particularly for rare or narrow-niche communities. To address this issue, this study proposes the KnowSim method that integrates expert-defined ecological knowledge to evaluate environmental similarity between locations. Vegetation types are predicted by assigning each site the type of its most ecologically similar sample. The method was tested in two regions of the Tibetan Plateau (Bome and Zoige), which exhibit contrasting yet complementary climatic and topographic conditions, together representing the Plateau’s typical environmental settings. Results demonstrate that KnowSim consistently outperforms statistical methods (Random Forest, eXtreme Gradient Boosting, Support Vector Machine, and Logistic Regression) in both accuracy and type diversity. The improvement is particularly evident for alliances with sparse samples, achieving up to 24.6% higher accuracy in Zoige for alliances with fewer than five training samples. Moreover, the predicted vegetation maps better align with ecological gradients and field observations, demonstrating both ecological interpretability and predictive robustness under sample-limited conditions.

Precipitation legacy effects (PLEs) profoundly alter the recovery trajectories of semi-arid grasslands under global climate change, necessitating mechanistic quantification for accurate climate risk assessment in these vulnerable ecosystems. Based on a seven-year precipitation simulation experiment followed by an in-situ natural recovery study in a semi-arid sandy grassland in Inner Mongolia, China, we characterized PLEs across multiple ecological hierarchies and varying precipitation patterns using data from the final treatment year and the first post-treatment year. Our results demonstrated that vegetation traits exhibited stronger PLEs than soil physicochemical properties. The magnitude of PLEs increased with higher functionalization (composition → productivity) and finer hierarchy (community → functional group), exceeding 50% when significant. Dry PLEs were generally stronger than wet PLEs; both exhibited bidirectional (positive/negative) performance, yet consistently showed an inverse relationship between vegetation traits and trait resilience. Mechanistically, PLEs of moderate wetting and extreme drying were primarily carried by vegetation-mediated information, whereas PLEs of moderate drying and spring drought legacies were mainly carried by soil-mediated material. Specifically, functional group composition served as the key information carrier: annuals primarily carried positive dry-PLEs and negative wet-PLEs, while perennials carried the opposite PLEs; and, the prevalent negative PLEs in community-level productivity and species diversity were specifically attributed to perennial grasses expansion after drying and annual forbs expansion after wetting. Soil available nutrients acted as the key material carrier, promoting PLEs in annuals via synergistic physicochemical pathways. Overall, both dry and wet PLEs generally impeded the vegetation recovery of the sandy grassland ecosystem, despite positive effects on certain finer-hierarchy ecosystem traits. We conclude that ignoring PLEs may lead to a severe underestimation of climate change risks in semi-arid ecosystems, particularly regarding their most sensitive components.

While mangrove restoration has a great potential for enhancing soil organic carbon (SOC) sequestration in coastal wetlands, microbial-mediated SOC decomposition introduces huge uncertainty to this process. Microbial carbon use efficiency (CUE) is a crucial trait for microorganisms controlling SOC turnover, but how mangrove restoration could affect microbial CUE remain unclear. Here, we investigated the effects of mangrove restoration on microbial CUE in a typical restored mangrove wetland and further explored its connection to microbial necromass carbon (MNC) content. We found that mangrove restoration increased microbial CUE by 37.84%–56.76% due to an increase in organic carbon quality and a shift in microbial community structure from fast-growing r-strategist (bacteria-dominated including Proteobacteria and Bacteroidota) to slow-growing K-strategist (fungal taxa and bacterial phyla such as Actinobacteriota, Acidobacteriota, and Chloroflexi). Microbial CUE was also positively correlated with MNC, explaining 73% and 69% variations in fungal and bacterial necromass C, respectively. These findings indicate that mangrove restoration enhances SOC sequestration not only through increased plant-derived carbon input but also by elevating microbial CUE and promoting MNC accumulation. Although bacterial necromass carbon showed a higher percentage increase, fungal necromass constituted the dominant portion of the accrued microbial-derived carbon pool, underscoring the critical role of fungal communities in the formation of stable SOC. Our study highlights the significant role of microbial processes in promoting SOC accumulation during mangrove restoration. These results emphasize the importance of incorporating microbial processes into coastal wetland restoration strategies to maximize C sequestration.

Livestock grazing can alter plant productivity and diversity through defoliation, trampling and excretion. To isolate effects of defoliation, researchers commonly employ clipping experiments, although these effects of defoliation can vary considerably depending on the intensity and duration of grazing, as well as the type of ecosystem. Here, we compiled data from 1006 pairs of observations across 96 studies to assess the impacts of simulated livestock defoliation on various measures of plant diversity (including evenness) and productivity in China’s grasslands. Overall, simulated livestock defoliation resulted in greater species richness and evenness, along with elevated aboveground net primary productivity (ANPP) and belowground biomass (BGB), but lower aboveground biomass (AGB). Moderate levels of defoliation produced a stronger positive response in diversity compared to light or heavy defoliation, similar to later-season defoliation. Such effects were absent in alpine meadows, which leading to a negative association between responses of diversity and elevation. AGB was reduced by defoliation in all contexts, while BGB increased more when defoliation was light, later in the season, and with shorter experimental durations; these effects were stronger in drier areas. Simulated grazing’s effects on ANPP switched from positive to negative as intensity increased. Changes in diversity were positively correlated with changes in ANPP in response to defoliation. These findings highlight that the effects of defoliation are context-specific in China’s grasslands, with important implications for grassland management and conservation.