Study On The Response Mechanism Of Main Vegetation Types Growth Variation To Climate Change In Africa Based On GLASS-LAI

Based on the latest GLASS-LAI data set,this article analyzed the spatial patterns of vegetation and its changing trends from 1982 to 2012 in Africa.The annual and interannual variations of LAI and the relations between LAI and climate factors in African rain forests and African savanna were analyzed using temperature and precipitation data.Main conclusions are as follows:(1)The spatial pattern of LAI in Africa was centered on the equator and decreased progressively to the north and south side and the pattern was similar to the vegetation zones.The research area is not typical tropical rain forest but belonged to tropical monsoon forest.(2)The interannual variation curve of Africa LAI was divided in 1994,the first stage of LAI showed a slight oscillation trend,the second stage of LAI showed a significantly and stable rising trend.LAI trend in African rain forests research was similar with the whole Africa but the fluctuation range of LAI in savanna was much larger.(3)The LAI and the temperature and the precipitation have positive correlation in rain forests..In savanna,the LAI and the temperature have negative correlation,the LAI and the precipitation have positive correlation.(4)Scenarios of the relationship ALAI between climate response in African rain forests and African savanna can be divided into out of sync with the regular and sync up.It also can be divided into four categories:ALAI is consistent with both precipitation and temperature trend;ALAI is only consistent with precipitation;ALAI is only consistent with temperature trend;ALAI is in contrast to both precipitation and temperature trend.The year that ALAI is of out of sync account for almost 80%.(5)The response mechanisms of LAI to climate change have four types:hydrothermic factor leading at the same time;hydrothermic factor leading at the different time;precipitation leading;extreme precipitation leading.The amplitude of variation of precipitation and temperature in different types are much difference.In African rain forests,the extreme precipitation leading type has the upper hand,in African savanna,the precipitation leading type dominate.(6)The precipitation is the controlling factor to change annual variance for both vegetation zones LAI,but in extreme precipitation leading type,precipitation threshold for both has a very big difference.The vegetation in savanna has a weak resistibility and resilience to climate change than rain forests.