Global Change Biology最新文献

Understanding how extreme climate events reshape the temperature response of ecosystem respiration (Re) is critical for predicting carbon–climate feedbacks. Here, we combine observational data and land surface model simulations to investigate Re responses to heatwaves, focusing on temperature sensitivity (Q₁₀) and thermal hysteresis. We develop a quantitative framework capturing hysteresis via temperature thresholds, their seasonal timing, and phase-specific Q₁₀ indices (Q_10,I, warming phase; Q_10,II, cooling phase). Flux-tower observations from the 2003 and 2018 heatwaves showed widespread amplification of thermal hysteresis in comparison with years without heatwaves. This amplification was primarily driven by asymmetric shifts in thermal sensitivity, especially a dominant decline in Q_10,II. The response of ecosystem respiration after summer is the most affected in years that have experienced strong heatwaves at most sites. Q_10,II retains strong associations with the timing of optimal temperature (r = 0.55), whereas Q_10,I becomes largely decoupled. Principal component analysis further confirms this divergence, with the two phase-specific sensitivities varying along orthogonal axes under heatwaves. We further analyzed individual sites to see how much each Q₁₀ phase contributed to the overall change in temperature sensitivity. Across sites, the temperature sensitivity of respiration in the post-heatwave phase accounts for an average of 71% of the total phase-specific Q₁₀ change induced by heatwaves. This reinforces the central role of Q_10,II in amplifying thermal hysteresis. Structural equation modeling shows that the heatwave-amplified thermal hysteresis in Re is fully mediated by Q_10,II decline, shaped by both thermal thresholds and their seasonal timing. These findings reveal a phase-asymmetric temperature sensitivity of Re that underpins thermal hysteresis, suggesting that short-term heatwaves could trigger prolonged carbon losses even under post-peak warming scenarios.

Biological invasion is a major component of global change, and co-invasion of multiple invasive species is becoming increasingly common under accelerating globalization, climate warming, and land-use change. Such co-invasions can generate non-additive impacts on ecosystems, either exacerbating or mitigating invasion outcomes, yet their ecological consequences and underlying mechanisms remain poorly understood. We conducted a two-phase greenhouse experiment using Solidago canadensis as a focal invader and 16 co-occurring invaders to condition soils in monocultures and mixtures, and then tested effects of these soils on a native plant community. We found that non-additive effects of co-invasions on native community biomass were generally negative, with phylogenetically distant co-invaders exerting stronger negative effects. These patterns were largely driven by synergistic increases in the richness of putative soil fungal pathogens induced by distantly related co-invaders. A complementary field survey confirmed these patterns in natural communities, showing that greater phylogenetic distance among co-invaders was associated with higher richness of putative soil fungal pathogens and stronger reductions in native plant abundance. Our study provides the first empirical evidence that evolutionary relatedness among co-invaders predicts the direction and magnitude of their combined impacts via soil microbial pathways. These findings highlight the importance of incorporating evolutionary and belowground mechanisms into invasion theory, and underscore the urgent need to recognize co-invasion as a key process for predicting and managing invasion impacts under global change.

Soil protists significantly influence ecosystem multifunctionality (EMF) through their roles in microbial predation, parasitism, and organic matter decomposition. However, the multifaceted contributions of protist diversity, along with its interactions with other microbial groups and plant diversity, to EMF—especially under climate-induced stresses such as drought—remain poorly understood. To address this knowledge gap, we conducted a factorial microcosm experiment, manipulating microbial diversity (protists, bacteria and fungi), plant species richness, and drought stress. In total, 203 microcosms were established, generating 812 soil samples and 2436 amplicon sequencing libraries. Using structural equation modelling (SEM) and multiple regression analyses, we found that protist diversity was positively correlated with EMF, carbon sequestration, soil organic matter (SOM) decomposition, and nutrient cycling. Furthermore, protist communities exhibited distinct, phylum-specific relationships with these ecosystem functions. Under drought conditions, microbial interaction networks experienced significant restructuring, with protists emerging as keystone taxa—enhancing protist connectivity and highlighting their central role in ecosystem resilience, especially in relation to leaf carbon dynamics. Our findings provide novel empirical evidence that protists act as multitrophic integrators in soil ecosystems and highlight their role in buffering ecosystems against global environmental change.

Plant and arbuscular mycorrhizal (AM) fungal diversity are both positively linked to ecosystem productivity across diverse ecosystems. However, given their high sensitivity to climate extremes such as extreme drought, the persistence and adaptability of these diversity-productivity relationships under rapid climate changes remain poorly understood. To address this, we established a grassland experiment at two proximate sites with distinct natural plant and AM fungal communities, imposing two contrasting extreme drought regimes (intense and chronic), each exceeding a 20-year recurrence interval based on site-specific precipitation records. We show that AM fungal diversity consistently outperforms plant diversity in predicting plant aboveground/net primary productivity (ANPP/NPP), as well as compositional shifts in plant species productivity, despite pronounced drought sensitivity in both communities. Notably, enhanced drought resistance in plant productivity was primarily associated with the stability of AM fungal richness rather than plant richness, highlighting their mutual dependence under extreme drought. Structural equation modelling confirmed that AM fungal richness buffered drought effects on ANPP, NPP and plant richness, with stronger effects on ANPP and NPP than those of plant richness and soil properties. These results suggest that AM fungal diversity may play a greater role than plant diversity in buffering plant communities against climate extremes. While causality remains to be fully resolved, these findings shed light on the adaptive significance of this ancient symbiont in sustaining ecosystem functioning under rapid climate change.