Active Restoration of Carbon Poor Degraded Grassland Accelerated Subsoil Carbon Accumulation and Turnover

The study, conducted in Zoige County on the eastern Qinghai–Tibet Plateau, examined three alpine grassland types differing in initial soil organic carbon (SOC) content (C-rich, C-middle, and C-poor) under non-restored, passively restored, and actively restored conditions. In August 2022, vegetation surveys measured species composition, coverage, height, and aboveground biomass, while soil samples were collected from 0–10 cm and 20–30 cm depths for physico-chemical analyses, bulk density, and microbial biomass measurements. Additional soil cores were taken for belowground biomass. Active restoration involved sowing locally adapted grass species, whereas passive restoration relied on natural recovery with grazing exclusion. Laboratory analyses determined plant nutrients, SOC, total C and N, and microbial biomass C and N. Soil incubation experiments at three temperatures (5 °C, 15 °C, 25 °C) assessed SOC mineralization rates and temperature sensitivity (Q₁₀), with CO₂ release monitored over 28 days.