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Global patterns of soil microbial biomass

2011Global patterns of soil microbial biomass.SERNA CHAVEZ Hector Mario (Mexico)
Organisation:University of Coimbra, Coimbra (PT) - Free University of Amsterdam (NL)Supervisor :Rui Ribeiro (UC) & Peter van Bodegom (VU)
Summary: The microbial world embed in the soil environment is enormous. The unseen majority represented by soil microorganisms plays a key role in the provision of soil ecosystem services. Although patterns and drivers of microbial abundance have been described at local and regional scales, a unifying driver, or set of drivers, for global soil microbial biomass is still missing. In the present meta-analysis we aimed to quantify and explain worldwide patterns in soil microbial abundance using a dataset of microbial biomass-C estimates across the major biomes on Earth and 0.5 latº×0.5 logº gridded databases of climate normals and soil physical-chemical parameters. Climate factors related to water supply availability and soil N and C content were the main drivers of global microbial biomass and the microbial C-to-soil organic C (CMic/COrg) ratio, suggesting cross-biome water and nutrient limitations. High soil microbial biomass-C content and CMic/COrg ratios were found for tropical forest, temperate grassland and temperate coniferous forest. On the other hand, low microbial biomass-C content and CMic/COrg ratios were found in desert, tundra and boreal forest biomes. The multivariate linear models presented in this meta-analysis estimated that across biomes CMic/COrg ratio rarely exceeds 4%. Moreover, the average global CMic/COrg was estimated between 1.5 and 1.7 %. Our multivariate models also estimated 1.5×1016 g CMic of global microbial biomass, which represents 0.8% of the global soil organic C pool and 2.3% of the C stored in plants across the land surface. The global patterns of microbial biomass abundance and CMic/COrg ratio present common environmental drivers, suggesting that across biomes microbial biomass responds to the drivers of soil organic C.