Patterns and drivers of soil carbon change (1980s-2010s) in the northeastern Qinghai-Tibet Plateau

• DOI: 10.1016/j.geoderma.2023.116488
• Publication Date: 2023-04-29T03:52:16Z
• Authors: Xia Liu; Tao Zhou; Xia Zhao; Peijun Shi; Yajie Zhang; Yixin Xu; Hui Luo; Peixin Yu; Peifang Zhou; Jingzhou Zhang
• Keywords: Soil carbon; Soil survey; Carbon sink; Thermokarst; Soil respiration

Rapid climate warming, permafrost degradation and widespread vegetation improvement on the Qinghai-Tibet Plateau (QTP) have caused carbon input via photosynthesis output through soil respiration to significantly increase in recent decades; thus, its role as a sink/source is unclear highly disputed, especially at different depths. In this study, we took Qinghai (northeastern QTP), with an area of 7.2 × 105 km2 (permafrost accounts for 52% land) elevation ranging from 1669 m 6548 m, study region estimated spatial pattern organic (SOC) stock changes depths 1980s 2010s. The paired site observations SOC stocks second national survey 2010s field literature were compiled then combined 77 related environmental factors drive multiple machine learning models (random forest, gradient-boosting machine, Cubist), which patterns (0–30, 30–50, 50–100 cm) revealed. results indicated that increased 0–100 cm over past three decades, mean net accumulation rate 7.36 g C m−2 yr−1 or total 0.153 Pg C. Compared seasonally frozen soil, more significant increases observed depth (9.71 vs. 4.81 yr−1). However, layers showed differences. Specifically, substantially topsoil layer (0–30 cm), 7.82 yr−1; middle (30–50 had slight increase, 1.69 decreased bottom (50–100 loss 2.15 yr−1. We found change was key driver layer. With depth, importance increased. concluded climate-driven losses deep offset by vegetation-driven inputs top layers, triggering plant-dominated negative feedback warming. temperature continuing however, must pay attention risk release layers.