Rising Temperature May Trigger Deep Soil Carbon Loss Across Forest Ecosystems.

ABSTRACT: Significantly more carbon (C) is stored in deep soil than in shallow horizons, yet how the decomposition of deep soil organic C (SOC) will respond to rising temperature remains unexplored on large scales, leading to considerable uncertainties to predictions of the magnitude and direction of C-cycle feedbacks to climate change. Herein, short-term temperature sensitivity of SOC decomposition (expressed as Q ₁₀) from six depths within the top 1 m soil from 90 upland forest sites (540 soil samples) across China is reported. Results show that Q ₁₀ significantly increases with soil depth, suggesting that deep SOC is more vulnerable to loss with rising temperature in comparison to shallow SOC. Climate is the primary regulator of shallow soil Q ₁₀ but its relative influence declines with depth; in contrast, soil C quality has a minor influence on Q ₁₀ in shallow soil but increases its influence with depth. When considering the depth-dependent Q ₁₀ variations, results further show that using the thermal response of shallow soil layer for the whole soil profile, as is usually done in model predictions, would significantly underestimate soil C-climate feedbacks. The results highlight that Earth system models need to consider multilayer soil C dynamics and their controls to improve prediction accuracy.

SUBMITTER: Li J 

PROVIDER: S-EPMC7539220 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature