Shrub expansion increases particulate organic carbon accumulation through reduced shoot litter decomposition rates

The study site is located in Tianzhu Tibetan Autonomous County, Gansu Province, China (2960 m a.s.l.).The core data were obtained through paired field sampling and in situ microcosm decomposition experiments, including:Vegetation and litter traits: Above- and belowground biomass, litter inputs, and initial chemical properties (C, N, P, lignin, and cellulose contents) of herbaceous plants and the dominant shrub (Potentilla fruticosa).Litter decomposition dynamics: Mass loss and decomposition rate constants (k) of shoot and root litter over a two-year in situ incubation.Soil carbon fractions and microbial properties: Total SOC, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), and phospholipid fatty acids (PLFA) in the 0–20 cm and 20–40 cm soil layers.Purpose: This dataset aims to elucidate the mechanistic links between vegetation shifts (shrubification) and soil C stabilization, demonstrating that poor-quality shrub litter drives POC accumulation and MAOC depletion.

These data provide essential support for predicting the vulnerability of soil carbon pools in alpine grasslands under global environmental change.