关键词: 高寒草甸, 微生物残体碳, 真菌群落, 网络稳定性

Abstract: Microbial necromass carbon (MNC) is an important component of the soil carbon sink in alpine meadows on the Qinghai-Tibet Plateau. However, we still know little about how soil properties and the microbial community regulate MNC during ecosystem restoration. This study examined the temporal dynamics of MNC components (bacterial and fungal) and microbial network stability across a 20-year restoration chronosequence (1, 5, 7, 13, and 20 years). The contents of bacterial necromass carbon (BNC), fungal (FNC), and total MNC increased rapidly during the early restoration phase, peaking at 7 years, followed by a decline in later stages. At this peak stage, bacterial network stability reached a relatively high level, in contrast to significantly lower fungal network stability. Random Forest modeling identified soil water content, particulate organic carbon, soil organic carbon, and total nitrogen as dominant abiotic predictors of MNC. Biotically, fungal network stability was a key determinant, showing a significant negative correlation with MNC accumulation. This pattern was linked to the dynamics of ectomycorrhizal fungi. Collectively, these results reveal that MNC sequestration is jointly regulated by soil resource availability and fungal community stability, providing new insights into the microbial mechanisms underlying soil carbon recovery in restored alpine ecosystems.

Key words: Alpine grassland, Microbial necromass carbon, Fungal community, Network stability