A meta-analysis of tropical land-use change effects on the soil microbiome: Emerging patterns and knowledge gaps

Modifications to vegetation and soil due to changes in land use have the potential to alter the soil microbiome, with consequences for carbon and nutrient cycling. Despite the important function of soil microorganisms, little is known about their response to land-use change, especially in tropical regions where current rates of land conversion are greatest. The aim of this meta-analysis was to examine how land-use change influences soil microbial properties in tropical ecosystems and to identify current trends and knowledge gaps in the literature. We identified 83 published paired studies that reported data on microbial biomass, abundance, composition, and enzyme activity under representative land-use changes in the tropics. We calculated response ratios for studies that compared the following: reference forests to (a) agriculture, (b) pastures, (c) plantations, and (d) secondary forests. Soil microbial biomass decreased with forest conversion to agriculture and plantations. Microbial biomass response to land-use change depended on rainfall classes, although this was the only microbial variable which had sufficient data to test for a rainfall effect. Microbial abundance and enzyme activity showed variable results depending on the type of forest conversion. Microbial diversity and richness did not show any pattern with forest conversion or recovery to secondary forests. Published studies were not representative of the range of biophysical conditions observed in the tropics. Sites in moist regions in the American tropics were overrepresented. To better predict how land-use change affects the soil microbiome and its contribution to nutrient cycling, research should reflect observed environmental variation in the tropics. in Spanish is available with online material.