Variation of Leaf Area Index in China from 1982 to 1999 and Its Relationship with Climate Change

Using the AVHRR Pathfinder remote sensing data of leaf area index (LAI) during 1982-1999 and observed temperature and precipitation data collected at 730 meteorological stations in China, the changes in seasonal LAI, LAI in the growing season and annual LAI are investigated in different areas of China (including Northeast China, North China, the Yangtze valley, South China and Southwest China). Their relationships with climate change (temperature and precipitation) are also explored. Results show that in most areas of China, annual LAI and LAI in the growing season has been increasing during the study period, which are mainly caused by the rising temperature. Due to the difference in seasonal and regional climate, there exist obvious regional and seasonal heterogeneities in the LAI variation tendency. From the perspective of regional averages, both annual LAI and LAI in the growing season over different regions demonstrate an increasing trend, especially in South China. Therefore South China might be a potential carbon sink under the context of global change. On the seasonal scale, regional average LAI in different sub-regions basically has been increasing as well, especially in the spring. In addition, changes in LAI are mainly attributed to the variation in temperature. However, impacts of human activities, such as agricultural activities and urbanization, on the LAI changes in the North China Plain, the Yangtze River delta and the Pearl River delta couldn't be ignored.