Responses of soil respiration to experimental warming in an alpine steppe on the Tibetan Plateau

Abstract

High-latitude and high-altitude ecosystems store large amounts of carbon (C) and play a vital role in the global C cycle. Soil respiration (R S) in these ecosystems is believed to be extremely sensitive to climate warming and could potentially trigger positive C-climate feedback. However, this evidence is largely derived from wet ecosystems, with limited observations from dry ecosystems. Here, we explored the responses of R S, autotrophic (R A), and heterotrophic (R H) respiration under experimental warming in a dry ecosystem, an alpine steppe on the Tibetan Plateau. We assessed the effects of soil temperature and moisture dynamics on R S, R A, and R H and performed a meta-analysis to examine whether the warming effects observed were similar to those reported in wet ecosystems, including Tibetan alpine meadow and arctic ecosystem. Experimental warming did not alter R S, R A, and R H in this alpine steppe, likely because decreased soil moisture constrained positive warming effects. In contrast, the meta-analysis revealed that R S exhibited a significant increase under experimental warming in both the Tibetan alpine meadow and arctic wet tundra. These results demonstrate that R S exhibits different responses to climate warming between dry and wet ecosystems, suggesting potential more complex C-climate feedback in cold regions.