Elevation‐dependent soil and plant responses to a decade of warming and species removal

Abstract

Understanding how ecosystems retain or release carbon under warming is a critical challenge. Dominant plant species, which contribute the most biomass, can mediate ecosystem responses to warming by modifying microclimate and nutrient cycling. To investigate how warming and shifts in plant dominance interact to affect carbon and nutrient dynamics, we conducted a decade‐long field experiment combining in situ warming and dominant species removal at a low‐ and at a high‐elevation montane meadow site. We hypothesized that warming would enhance plant productivity and soil nutrient availability by altering microclimate conditions, which would then lead to shifts in soil carbon. Warming increased soil temperature most strongly at the high‐elevation site, though soil moisture responses to warming were limited at both elevations. Species removal reduced plant biomass more strongly at the low‐elevation site, though the most pronounced differences in microclimate, biomass, and soil properties occurred between elevations. While warming reduced potential mineralization rates and removal increased total soil nitrogen, warming and removal had limited effects on total soil carbon (C). However, they significantly altered the composition of soil organic matter, shifting the balance between plant‐ and microbial‐derived compounds. These findings suggest that even in the absence of changes to bulk C pools, warming and vegetation change can influence long‐term soil carbon stability by modifying the quality of organic matter and thus its physicochemical properties and decomposability. Our results highlight the importance of dominant species and elevation context in shaping belowground responses to climate change, driving shifts in microclimate, vegetation composition, and carbon pools that may influence soil carbon stability and ecosystem resilience.