Global Change Biology最新文献

The carbon sink function performed by the different vegetation types along the environmental gradient in coastal zones plays a vital role in mitigating climate change. However, inadequate understanding of its spatiotemporal variations across different vegetation types and associated regulatory mechanisms hampers determining its potential shifts in a changing climate. Here, we present long-term (2011–2022) eddy covariance measurements of the net ecosystem exchange (NEE) of CO₂ at three sites with different vegetation types (tidal wetland, nontidal wetland, and cropland) in a coastal zone to examine the role of vegetation type on annual carbon sink strength. We found that the three study sites are stable carbon sinks and are influenced by their distinct physiological and phenological factors. The annual NEE of the tidal wetland, nontidal wetland, and cropland were determined predominantly by the seasonal peaks of net CO₂ uptake, release, and duration of CO₂ uptake period. Furthermore, the changes in annual NEE were sensitive to climatic variables, as spring mean air temperature reduced the carbon sink strength in the tidal wetland, maximum daily precipitation in summer reduced it in the nontidal wetland, and summer mean global radiation elicited the same effect in the cropland. Finally, a worldwide database of the three vegetation types was compiled, using which we further validated the global consistency of the biological controls. Overall, these results emphasize the importance of considering the underlying mechanisms by which vegetation types influence NEE for the accurate forecasting of carbon sink dynamics across different coastal vegetation types under climate change.

Unraveling how agricultural management practices affect soil biota network complexity and stability and how these changes relate to soil processes and functions is critical for the development of sustainable agriculture. However, our understanding of these knowledge still remains unclear. Here, we explored the effects of soil management intensity on soil biota network complexity, stability, and soil multifunctionality, as well as the relationships among these factors. Four typical land use types representing a gradient of disturbance intensity were selected in calcareous and red soils in southwest China. The four land use types with increasing disturbance intensity included pasture, sugarcane farmland, rice paddy fields, and maize cropland. The network cohesion, the network topological features (e.g., average degree, average clustering coefficient, average path length, network diameter, graph density, and modularity), and the average variation degree were used to evaluate the strength of interactions between species, soil biota network complexity, and the network stability, respectively. The results showed that intensive soil management increased species competition and soil biota network complexity but decreased soil biota network stability. Soil microfauna (e.g., nematode, protozoa, and arthropoda) stabilized the entire soil biota network through top-down control. Soil biota network stability rather than soil biota network complexity or soil biodiversity predicted the dynamics of soil multifunctionality. Specifically, stable soil communities, in both the entire soil biota network and selected soil organism groups (e.g., archaea, bacteria, fungi, arthropoda, nematode, protozoa, viridiplantae, and viruses), support high soil multifunctionality. In particular, soil microfauna stability had more contributions to soil multifunctionality than the stability of soil microbial communities. This result was further supported by network analysis, which showed that modules 1 and 4 had greater numbers of soil microfauna species and explained more variation of soil multifunctionality. Our study highlights that soil biota network stability should be considered a key factor in improving agricultural sustainability and crop productivity in the context of increasing global agricultural intensification.

Carbon use efficiency (CUE) of microbial communities in soil quantifies the proportion of organic carbon (C) taken up by microorganisms that is allocated to growing microbial biomass as well as used for reparation of cell components. This C amount in microbial biomass is subsequently involved in microbial turnover, partly leading to microbial necromass formation, which can be further stabilized in soil. To unravel the underlying regulatory factors and spatial patterns of CUE on a large scale and across biomes (forests, grasslands, croplands), we evaluated 670 individual CUE data obtained by three commonly used approaches: (i) tracing of a substrate C by ¹³C (or ¹⁴C) incorporation into microbial biomass and respired CO₂ (hereafter ¹³C-substrate), (ii) incorporation of ¹⁸O from water into DNA (¹⁸O-water), and (iii) stoichiometric modelling based on the activities of enzymes responsible for C and nitrogen (N) cycles. The global mean of microbial CUE in soil depends on the approach: 0.59 for the ¹³C-substrate approach, and 0.34 for the stoichiometric modelling and for the ¹⁸O-water approaches. Across biomes, microbial CUE was highest in grassland soils, followed by cropland and forest soils. A power-law relationship was identified between microbial CUE and growth rates, indicating that faster C utilization for growth corresponds to reduced C losses for maintenance and associated with mortality. Microbial growth rate increased with the content of soil organic C, total N, total phosphorus, and fungi/bacteria ratio. Our results contribute to understanding the linkage between microbial growth rates and CUE, thereby offering insights into the impacts of climate change and ecosystem disturbances on microbial physiology with consequences for C cycling.

Rapid warming in northern lands has led to increased ecosystem carbon uptake. It remains unclear, however, whether and how the beneficial effects of warming on carbon uptake will continue with climate change. Moreover, the role played by water stress in temperature control on ecosystem carbon uptake remains highly uncertain. Here, we systematically explored the trend in the temperature control on gross primary production (measured by “S_GPP-TAS”) across northern lands (> 15°N) using a standardized multiple regression approach by controlling other covarying factors. We estimated S_GPP-TAS using three types of GPP datasets: four satellite-derived GPP datasets, FLUXNET tower observed GPP datasets, and GPP outputs from nine CMIP6 models. Our analysis revealed a significant positive-to-negative transition around the year 2000 in the trend of S_GPP-TAS. This transition was primarily driven by synchronized changes in soil water content over time and space. The S_GPP-TAS trend transition covered about 32% of northern lands, especially in grasslands and coniferous forests where leaf water mediation and structural overshoot accelerated the drought-induced transition, respectively. In the future, widespread negative S_GPP-TAS trends are projected in northern lands corresponding with decreasing soil water availability. These findings highlight the shrinking temperature control on northern land carbon uptake in a warmer and drier climate.

Climate change and biological invasions are affecting natural ecosystems globally. The effects of these stressors on native species' biogeography have been studied separately, but their combined effects remain overlooked. Here, we develop a framework to assess how climate change influences both the range and niche overlap of native and non-native species using ecological niche models. We hypothesize that species with similar niches will experience both range reductions and increased niche overlap under future climates. We evaluate this using the ongoing invasion of smallmouth bass (Micropterus dolomieu) and northern pike (Esox lucius) on the native habitats of redband trout (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus) in western North America. Future climate conditions will reduce habitat suitability for native and non-native species, but an increased niche overlap might exacerbate negative effects on native fishes. Our framework offers a tool to predict potential species distribution and interactions under climate change, informing adaptive management globally.

Leaf photosynthesis and respiration are two of the largest carbon fluxes between the atmosphere and biosphere. Although experiments examining the warming effects on photosynthetic and respiratory thermal acclimation have been widely conducted, the sensitivity of various ecosystem and vegetation types to warming remains uncertain. Here we conducted a meta-analysis on experimental observations of thermal acclimation worldwide. We found that the optimum temperature for photosynthetic rate (T_opt) and the maximum rate of carboxylation of Rubisco (T_optV) in tropical forest plants increased by 0.51°C and 2.12°C per 1°C of warming, respectively. Similarly, T_opt and the optimum temperature for maximum electron transport rate for RuBP regeneration (T_optJ) in temperate forest plants increased by 0.91°C and 0.15°C per 1°C of warming, respectively. However, reduced photosynthetic rates at optimum temperature (A_opt) were observed in tropical forest (17.2%) and grassland (16.5%) plants, indicating that they exhibited limited photosynthetic thermal acclimation to warming. Warming reduced respiration rate (R₂₅) in boreal forest plants by 6.2%, suggesting that respiration can acclimate to warming. Photosynthesis and respiration of broadleaved deciduous trees may adapt to warming, as indicated by higher A_opt (7.5%) and T_opt (1.08°C per 1°C of warming), but lower R₂₅ (7.7%). We found limited photosynthetic thermal acclimation in needleleaved evergreen trees (−14.1%) and herbs (−16.3%), both associated with reduced A_opt. Respiration of needleleaved deciduous trees acclimated to warming (reduced R₂₅ and temperature sensitivity of respiration (Q₁₀)); however, broadleaved evergreen trees did not acclimate (increased R₂₅). Plants in grasslands and herbaceous species displayed the weakest photosynthetic acclimation to warming, primarily due to the significant reductions in A_opt. Our global synthesis provides a comprehensive analysis of the divergent effects of warming on thermal acclimation across ecosystem and vegetation types, and provides a framework for modeling responses of vegetation carbon cycling to warming.