Abstract: The earth′s boundary layer heat source is the result of downward short-wave solar radiation and upward long-wave surface radiation,which are closely correlated with the organism′s activities in the boundary.Therefore it is important to study the long-wave radiation variations for understanding ecosystem matter and energy fluxes.By analyzing the observation data measured by flux covariance system of alpine Kobresia humilis meadow and Potentilla fruticosa shrubland on the northeast of Qinghai-Tibetan Plateau in 2003,the variations and comparisons of upward long-wave radiation(ULR),downward long-wave radiation(DLR) and surface effective long-wave radiation(ELR) on the two vegetation types were discussed.The results showed that there were obvious diurnal and monthly variations of ULR,DLR and ELR on the two vegetation types.The peak value of monthly mean diurnal variations of ULR and DLR on the alpine meadow and shrubland appeared at 14∶00 and 16∶00-18∶00(Beijing time) and the lowest both appeared in the morning,respectively.Moreover,the maximum of ELR occurred at 14∶00 and the minimum happened at 8∶00.The highest value of monthly DLR and ULR occurred from July to September and the lowest in January and February;while ELR showed a complex change tendency.Overall,ULR and DLR of Potentilla fruticosa shrubland was much higher than that of Kobresia humilis meadow.

Key words: Vegetation types, Vegetation types, Upward long-wave surface radiation, Downward long-wave radiation, Climatological characteristics, Comparison analysis