Global Change Biology最新文献

Alpine permafrost constitutes a substantial climate-sensitive system due to compressed environmental gradients and elevation-dependent forcing. However, projection uncertainties persist from unresolved altitudinal thresholds governing permafrost responses. Here, we integrate large-scale thaw-depth investigations across Tibetan permafrost with regional climate, vegetation, and soil data sets, to identify an elevational transition between 4600 and 5000 m, where coupled climatic–vegetation–soil interactions shift abruptly. Below this range, vegetation-buffered permafrost is dominated by NDVI and SOC controls, while climate-exposed permafrost above it is governed by temperature. As warming intensifies across scenarios, maximum thaw-depth sensitivity to temperature rises by approximately 1.5-fold (from 0.17 to 0.25 m °C⁻¹). Projections incorporating this elevation dependence indicate near-linear Tibetan permafrost contraction, with 6.7%–64.6% area loss expected by 2100, liberating approximately 3.6–14.4 Pg C of cryolocked carbon subject to post-thaw biogeochemical release. These findings highlight the critical role of elevation-dependent controls in shaping permafrost-climate feedbacks and underscore the urgency of incorporating altitudinal thresholds into Earth system models to improve the accuracy of future carbon flux predictions from alpine permafrost regions.

Drought stress is a major threat to global food security. It remains uncertain whether conserved drought-responsive microbes can be recruited by different crop species to help their adaptation to drought and how this recruitment occurs. Herein, we identified drought-responsive rhizosphere microbial genera conserved across multiple crop species under drought stress and elucidated their in situ regulatory mechanisms. Integrated amplicon sequencing of rhizosphere microbiomes from 26 crop species indicated 6 core genera (Streptomyces, Glycomyces, Inquilinus, Amycolatopsis, Acinetobacter, and Promicromonospora) consistently enriched under drought. Soil conditioning with 46 shared rhizosphere metabolites among multiple crops demonstrated that trehalose, myo-inositol, and phenylalanine synergistically enrich the six genera. The soil microbiome conditioned with three compounds significantly increased root length and leaf water content when evaluated in greenhouse trials (tomato, cucumber, and watermelon) and sorghum field studies. Furthermore, the conditioned soil microbiome exhibited enrichment in pathways related to energy supply, protective compound synthesis, and plant interaction signaling, driven by six core genera. Pure culture experiments revealed a potential cross-phylum interaction; that is, Streptomyces could synthesize phenylalanine to recruit Acinetobacter. Our findings reveal a potential conserved rhizosphere metabolite-microbiome interactions across multiple crops, offering a talent pathway to steer soil microbiome for drought resistance.

Understanding the impact of nitrogen (N) enrichment on soil microbial community and its associations with ecosystem functionality is crucial, given rising global atmospheric N deposition and even greater agricultural inputs. Most previous studies simulating N deposition used single N species, yet the specific effects of different N forms are not fully understood. This limitation hinders our capacity to link changes in soil microbial communities with ecosystem multifunctionality and to assess the impact of atmospheric N deposition on ecosystem services. To bridge this knowledge gap, our study, conducted from 2016 to 2018 in a typical temperate grassland in Inner Mongolia, China, evaluated the differential effects of the addition of four N forms—ammonium bicarbonate (AC), ammonium nitrate (AN), ammonium sulfate (AS), and urea (UR)—on soil bacterial community structure and function, taxonomic interactions, and ecosystem multifunctionality. These forms were applied at five levels (0, 2, 10, 20, and 50 g N m⁻² year⁻¹) with five replicates as part of a long-term experiment. Our findings reveal that N forms in combination with increased N loading differentially influence bacterial community structure and functional characteristics, and co-occurrence networks, alongside ecosystem multifunctionality. Notably, AN/AS significantly reduced bacterial taxonomic and functional diversity and network complexity, unlike AC, which showed minimal changes. The alteration in bacterial community structure and function under AN/AS was more significantly linked to changes in ecosystem multifunctionality than those under AC/UR, with AC having minimal connections. Additionally, keystone taxa responded differently to N levels and showed varied correlations with ecosystem multifunctionality. These results underscore the distinct effects of different N forms on soil bacterial communities and their cascading influence on ecosystem multifunctionality, emphasizing the need for management practices targeted to the specific chemical species of N deposition and fertilization.

The microclimate temperature within forests can substantially deviate from measurements outside forests. Yet, the amount and direction of this buffering strongly depend on meteorological conditions outside forests, such as free-air temperature, wind speed, soil moisture, precipitation and solar radiation. Most studies on microclimate buffering focus on long-term averages at coarse temporal resolution (e.g., monthly to seasonal), potentially overlooking the impact of daily fluctuations, which are nonetheless critical for many forest species and processes. Here, we linked in situ measured air and soil temperatures, at the daily resolution over a period of more than 5 years across 45 European deciduous forests spanning a 2300-km latitudinal gradient, to daily variation in weather conditions (i.e., free-air temperature, precipitation, wind speed, soil moisture, solar radiation, day length and snow cover). We assessed the interactive effects of weather conditions and forest structural complexity (plant area index) and distance to the forest edge on air and soil temperature offsets. Temperature offsets are the difference between understory air or soil temperature and macroclimate reference conditions measured at weather stations in the open field. We show that relative effect sizes of free-air temperature prevailed over the effects of other weather variables to determine air and soil temperature buffering. In general, higher free-air temperatures, soil moisture, wind speed and snow cover led to more negative air and soil temperature offsets, with variations depending on forest structural complexity and season. Conversely, slightly increased air and soil temperature offsets were found as precipitation and solar radiation increased. Our study highlights the dominant role of daily free-air temperature fluctuations outside forests in shaping microclimatic buffering. We emphasize complex interaction paths between daily weather conditions, and forest structure and edge effects, offering valuable insights for next-generation microclimate models and enhancing our understanding of forest ecosystem responses to environmental change that account for microclimate.