Abstract: Based on the 1981-2000 GLOPEM NPP dataset and the corresponding monthly meteorological data, this paper analyzed the variation trends of vegetation productivity and climate in four counties in Huangnan Tibetan Autonomous Prefecture of Qinghai, calculated the correlation coefficients of NPP and climatic factors, and approached the main climatic factors affecting vegetation variation. In the four counties, the average NPP increased significantly in the 1980s, and decreased with fluctuation in the 1990s. Overall, the NPP had a slight decrease in Jianzha and Tongren counties, but an increase in Zeku and Henan counties. The weather became wetter and warmer in Jianzha and Tongren counties in the 1980s and in Zeku and Henan counties in the 1990s, while drier and warmer in Jianzha and Tongren counties in the 1990s and in Zeku and Henan counties in the 1980s. Precipitation was the most important climatic factor affecting the NPP in Jianzha County, while air temperature had much stronger effects on the NPP in Henan County. Due to the different thermal-moisture conditions, the correlation between NPP and air temperature from north to south was stronger, while that between NPP and precipitation was weaker. Rainfall use efficiency increased significantly from 1981 to 2000 in Henan County, but increased slightly in the other three counties. The rainfall in April and May had an important restraining effect on NPP. Therefore, increasing water supply in spring was an effective way for increasing NPP. If the future climate change was similar to that in the 1990s, the decrease of rainfall would have negative effects on the vegetation growth in Jianzha and Tongren counties, and positive effects in southern Huangnan. In the process of vegetation restoration, the northern and southern parts of the Prefecture should pay more attention to the moisture addition and thermal preservation.

Key words: Lead, Uptake, Distribution, Rice (Oryza sativa L.)