| 摘 要： |
Understanding the temporal dynamics of soil microbial biomass is crucial for assessing soil ecosystem functions and services, yet these dynamics are globally uncertain. Here, we compiled a data set of soil microbial biomass carbon (MBC) and nitrogen (MBN) from 1493 studies between 1988 and 2019 to elucidate their temporal trends and potential drivers. Results showed that global MBC and MBN significantly decreased by 0.033 Mg C ha-1 yr-1 and 0.007 Mg N ha-1 yr-1 at 0-30 cm soil depth, between 1988 and 2019, respectively, which might be primarily attributed to the warming of the climate, the increase in global precipitation, and reduction of soil organic carbon (SOC) stock. The rate of decline in MBC and MBN showed a non-linear trend: following a decline from 1988 to 1999, it slowed down until 2014, likely due to the global warming hiatus. Afterward, the pace of decline increased again from 2015 to 2019. Boreal biomes experienced the largest decrease in soil microbial biomass with the reduction rate of MBC being 4.3 times higher than in temperate biomes, showing a higher sensitivity in boreal biomes to climate change. Grassland ecosystems also exhibited greater reductions, possibly driven by their degradation. These findings shed valuable insights on the long-term dynamics of soil microbial biomass on a global scale over the last three decades. Furthermore, this study underscores the importance of preserving soil microbial biomass as a key strategy to mitigate the adverse effects of future climate change, thereby sustaining ecosystem health and resilience. Soil microorganisms strongly determine carbon and nutrient cycling in terrestrial ecosystems. However, the temporal variations in soil microorganisms associated with climate change are subject to considerable uncertainties on a global scale, which seriously impedes our accurate predictions in future climate change. Here, we compiled a database of all previously published articles that reported microbial biomass carbon or nitrogen to investigate their temporal trends and potential drivers at the global scale. Our findings highlight the significant decrease in soil microbial biomass over the past three decades, possibly attributed to climate warming, increased global precipitation, and the reduction of soil organic carbon. Notably, the largest decreases were found in boreal biomes, likely due to their heightened sensitivity to climate change, and in grassland ecosystems, possibly caused by land degradation reducing carbon stocks and soil moisture. These insights into the long-term dynamics of soil microbial biomass are invaluable for planning strategies to mitigate the impacts of future climate change. This includes the need to preserve soil microbial biomass, which could help sustain ecosystem health and resilience, maintain nutrient cycling, and uphold soil fertility under changing climatic conditions. Global MBC and MBN declined at rates of 0.033 Mg C ha-1 yr-1 and 0.007 Mg N ha-1 yr-1 from 1988 to 2019 possibly due to climatic changes MBC in boreal biomes decreased 4.3 times faster than in temperate ones, documenting a higher sensitivity in boreal ones to climate change Large microbial biomass reduction in grassland ecosystems can be mitigated by carbon neutrality policies, like grassland restoration |
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