Elevation-dependent distribution of soil microbial necromass carbon in Pinus densata Mast. forests

Abstract

Soil microbial necromass carbon (MNC) is an important component of soil organic carbon (SOC). However, its distribution patterns and driving mechanisms in alpine forest ecosystems remain understudied. MNC plays a crucial role in soil carbon storage and stability, profoundly influencing the carbon cycling in sensitive ecosystems and under climate change. Therefore, elucidating the distribution patterns of MNC and the factors driving them is essential for understanding the carbon cycle in alpine ecosystems and predicting the impacts of climate change. This study focuses on the Pinus densata Mast. forests of the Sygera Mountain, examining the distribution of MNC by collecting soil profile samples from 0 to 40 cm depths along an elevational gradient (3100 m, 3400 m, and 3700 m). Our findings reveal the following: 1) The total MNC decreases with elevation, and fungal necromass carbon content is significantly higher than bacterial necromass carbon at all elevations and soil depths; 2) Microbial necromass carbon content decreases with increasing soil depth, and its relative contribution to SOC increases with depth; 3) The content of MNC is primarily regulated by the joint effects of environmental factors and microbial characteristics, with soil nutrient content, elevation gradient, and microbial features being the main factors influencing the accumulation of MNC. This study elucidates the distribution patterns and driving factors of microbial necromass in alpine forest ecosystems, providing crucial scientific insights into the soil microbial carbon cycle in alpine ecosystems.