Carbon budgets and environmental controls in alpine ecosystems on the Qinghai-Tibet Plateau

•Few attempts are made to analyze difference in carbon budget among alpine ecosystems.•Vegetation types and climatic condition determine carbon source/sink of ecosystems.•Carbon emissions in forest and alpine steppe ecosystems were more sensitive to warming.•Water forcing were strong predictors of carbon flux in alpine steppe, meadow ecosystems.•Carbon fluxes of forest and cropland ecosystems were depend on temperature forcing.