Global Change Biology最新文献

Anthropogenic nitrogen (N) deposition alters forest functioning and their capacity to sequester carbon (C), yet its contribution to the forest C sink depends on N retention and allocation between plant biomass and soil pools. Despite high N deposition across China, the magnitude and drivers of N retention and contribution to forest C sequestration remain unclear due to a lack of systematic regional synthesis. Here, we synthesized data from decades of ¹⁵N tracer experiments spanning boreal to tropical regions of China to quantify the retention of deposited N, distribution among plant and soil pools, and contribution to forest C sequestration. On average, Chinese forests retained ~65% of the deposited N, with about two-thirds stored in the soil. Total retention and partitioning of N varied with climate, successional stage, and N forms. Soil organic layer retention declined, while mineral soil retention increased along a north–south gradient in mean annual temperature. Chronically N-saturated and disturbed forests exhibited low plant retention, whereas other forests showed substantial uptake across climate zones. Total ecosystem retention efficiency generally declined from boreal to tropical forests. Across successional stages, retention did not differ significantly; however, primary forests retained more deposited N in mineral soils, whereas plantations favored retention in the organic layer. Stoichiometric scaling indicates that CN response (kg C sequestered per kg deposited N) varies among forest types, ranging from ~7 to 40 kg C kg⁻¹ N, with boreal forests and plantations exhibiting the strongest C response due to greater N limitation. This suggests that over the past decade, N deposition enhanced C sequestration by approximately 0.11 Pg C year⁻¹, accounting for 20%–30% of China's forest C sink. Overall, these findings advance understanding of the drivers of deposited N retention and its contribution to C sequestration, with implications for predicting forest N and C dynamics under global change.

Over the last decades, climate change biology has become a central field in global science, yet knowledge production and its inclusion in global strategies remain profoundly unequal. Our bibliometric analysis of over 580,000 records shows that ~80% of author affiliations come from Global North institutions, meaning that research agendas, theoretical frameworks, and priorities are still largely shaped outside the regions with the highest biodiversity and greatest vulnerability to climate change. This imbalance reflects structural and historical inequalities that limit the ability of Global South countries to conduct autonomous research and sustain long-term monitoring. When research and funding originate abroad, local scientists are often excluded, leading to the loss of traditional knowledge, regional perspectives, and long-term capacity building. These dynamics leave tropical and subtropical bioregions (generally in the Global South) underrepresented in global climate knowledge. To address this imbalance, we propose six actions: invest in infrastructure and monitoring, strengthen local research networks, link funding to capacity building, promote open and equitable data access, connect science with regional policies, and foster intersectoral collaboration. We argue that truly effective climate change biology must be global, equitable, and diverse.

The symbioses between corals and microorganisms, including the endosymbiotic dinoflagellates (family Symbiodiniaceae) and bacteria, are central to coral health and functioning. Certain species of Symbiodiniaceae in the genus Durusdinium are known to confer enhanced thermotolerance to corals and could therefore be beneficial under global climate change. However, association with thermotolerant algal symbionts may come with trade-offs that affect long-term coral persistence, and this study reports on one potentially consequential trade-off. We exposed colonies of the coral Galaxea fascicularis hosting Symbiodiniaceae in the genus Cladocopium (C-corals) or Durusdinium (D-corals) to elevated temperature equivalent to ~9.5 degree heating weeks. While C-corals were heat-sensitive, as evidenced by reduced Symbiodiniaceae cell density, photochemical efficiency and tissue pigmentation, they were resilient to tissue loss, maintained a stable bacterial community under elevated temperature, and showed limited mortality (12.5%) at the end of the 15-week recovery. Conversely, D-corals showed limited Symbiodiniaceae photodamage or tissue pigmentation loss under elevated temperature and initially demonstrated heat resilience. However, D-corals exhibited tissue loss and a significant reduction in newly formed polyps under elevated temperature, which occurred in parallel with a shift in their bacterial community composition toward taxa linked to bleaching, disease or algal overgrowth (e.g., Sphingomonas). Most D-corals died at the end of the recovery period. The intracellular bacterial communities in Cladocopium and Durusdinium freshly isolated from the experimental corals revealed symbiont-specific patterns, where Durusdinium showed strong affiliation with the diazotroph Ruegeria sp. Our findings show that G. fascicularis associating with the thermally tolerant Durusdinium may have higher susceptibility to tissue loss relative to corals with Cladocopium symbionts. If this trade-off occurs across corals that can associate with both Cladocopium and Durusdinium, it can have profound implications for reef persistence under global climate change, and further study is critical to inform conservation strategies aiming to build resilient reefs.

Ecosystem carbon dynamics are governed by complex temporal dependencies and environmental interactions, yet these processes remain poorly understood and quantified across diverse biomes. Here, we developed an explainable LSTM-Attention framework that integrates LSTM networks, attention mechanisms, and gradient-based attribution methods to reveal temporal dependencies in ecosystem carbon flux responses by analyzing eddy covariance flux measurements from 71 sites spanning eight North American biomes. Using this approach, we identified three distinct temporal memory patterns governing carbon flux responses. Grasslands exhibit short-term memory dominance with exponentially increasing temporal contributions from distant to recent past. Deciduous broadleaf forests and wetlands show long-term memory dominance, with deciduous broadleaf forests displaying the strongest historical dependence (attribution values declining from 0.30 at 6 months to 0.045 at 1 month). Croplands and evergreen needleleaf forests demonstrate U-shaped dual memory patterns. Building on these temporal patterns, we identified biome-specific environmental drivers operating within each memory framework: wetlands primarily controlled by soil moisture, evergreen needleleaf forests by radiation, and closed shrublands by vapor pressure deficit. Beyond individual drivers, we uncovered critical nonlinear interactions that diverged from linear correlations at most sites (55 of 71 with ρ < 0.5). For instance, the carbon sink capacity of deciduous broadleaf forests depends on synchronized canopy development and photosynthetic activity, while closed shrublands show strong suppression of carbon uptake by atmospheric water deficit regardless of vegetation greenness, revealing how multiple drivers jointly regulate ecosystem functioning. Validating memory's fundamental role, ablation experiments confirmed that removing memory mechanisms degraded model prediction performance and altered environmental driver identification (Kendall's Tau < 0.5), demonstrating that temporal memory is integral to accurately modeling ecosystem carbon flux responses to environmental drivers. These findings provide mechanistic insights into temporal controls of carbon exchange across different biomes. This knowledge is critical for improving terrestrial carbon-climate feedback representations under global change.

Biocrusts are a critical component of terrestrial environments, playing vital roles in soil stability, carbon and nitrogen cycling, and ecosystem functioning, particularly in drylands. Yet their responses to global change stressors remain poorly understood, with most evidence derived from local-scale experiments. Here, we conducted a meta-analysis synthesizing 657 observations from 48 publications conducted at 38 sites to assess how structural traits (cover, species richness, and moss biomass) and a key functional trait (chlorophyll content) of biocrusts respond to warming, altered precipitation, nitrogen addition, and their interactions. We found that nitrogen addition produced the strongest overall decline in biocrust cover (−52%). Warming (−21%) also significantly reduced biocrust cover, and its combined effect with decreased precipitation caused greater losses (−44%). Species richness declined under combined warming and decreased precipitation (−8%). Chlorophyll content responded negatively to decreased precipitation (−26%), combined warming and decreased precipitation (−35%), and nitrogen addition (−21%), but increased under elevated precipitation (+55%). Moss biomass exhibited weak and inconsistent responses to nitrogen addition. The response of biocrusts varied among dominant biocrust types, ecosystems, and climate zones. Late-successional crusts (moss- and lichen-dominated) exhibited the strongest declines, whereas cyanobacterial crusts often persisted or even expanded under stress. Biocrusts in semi-arid grasslands were most negatively affected by warming and reduced precipitation, whereas those in humid tundra and forests were most sensitive to nitrogen addition. In addition, biocrust responses were shaped by the characteristics of global change manipulations, with warming and precipitation reduction being more sensitive to duration than magnitude, whereas nitrogen addition rate exerted stronger effects than duration. Together, these findings demonstrate that biocrusts are highly vulnerable to global change, potentially undermining their capacity to control erosion and regulate carbon and nutrient cycling. We emphasize the urgent need to safeguard biocrusts in a rapidly changing world.