Context dependence of warming‐induced shifts in montane soil microbial functions

Abstract High elevation and latitude ecosystems are experiencing high levels of anthropogenic atmospheric warming. Climate warming may directly change soil microbial activity and alter ecosystem carbon dynamics and productivity, but increasing evidence suggests these responses may depend on other biotic factors such as plant community composition and abiotic factors such as moisture. We examined how abiotic (warming) and biotic (presence of dominant plant species) factors interact to affect soil microbial processes. Our experiment deployed the independent and combined treatments of experimental warming and dominant plant species removal in a high and low elevation montane meadows. We analysed multiple soil microbial responses to warming and the presence of a dominant plant at three times throughout the growing season, including soil respiration, microbial metabolic functional diversity, microbial biomass carbon and nitrogen, and extracellular enzyme potential activity. Overall, there were few independent microbial responses to either the warming or the removal treatments. There was a significant interaction between warming and the removal of a dominant plant species, where microbial biomass and the activity of some microbial enzymes were lower in warmed plots where the dominant species was removed relative to control plots. The effect of warming on extracellular enzyme activity was typically observed only at the high‐elevation site. In contrast, we found that effects of warming were consistent across the growing season, despite strong temporal variation in microbial properties. Our results emphasize the need to further consider soil microbial responses to warming under multiple environments, including shifts in both biotic and abiotic factors, to aid in predictions of carbon dynamics under future global change. Read the free Plain Language Summary for this article on the Journal blog.