spatial variability of vegetation and topsoil organic carbon densities of alpine grasslands in the Qinghai-Tibetan Plateau

This study compiled data since 2000 for 422 alpine grassland sites in Qinghai Province, China, to investigate vegetation and organic carbon densities in the topsoil (at 0‒30 cm depth) and their spatial variations. The site-averaged belowground biomass carbon density (BOD) and topsoil organic carbon density (SOD) were both highest in alpine meadows with values of 0.43 ± 0.34 (Mean ± S.D.) and 12.52 ± 5.74 kg C/m2, respectively. They are about five times the lowest corresponding values of alpine desert steppes. The aboveground biomass carbon density (AOD) is not significantly different between alpine steppes and alpine desert steppes, and averaged 32.66 ± 22.02 g C/m2, around twice that for alpine meadows. The boosted regression tree models, integrated with spatial datasets of topographic attributes, mean annual air temperature and precipitation, and mean annual maximal normalized difference vegetation index, yielded area-averaged AOD, BOD, and SOD values of 22.67 ± 4.48 g C/m2, 0.37 ± 0.074 kg C/m2, and 9.53 ± 4.48 kg C/m2, respectively.