Characteristics Of Vegetation Changes And Its Responses To Climate Change In Desert/Grassland Biome Transition Zone In The Last 30 Years Based On GIMMS 3g

The vegetation of desert/grassland biome transition zone is sensitive to the globe climate change. Thus, the study about vegetation phenology changes of the desert/grassland biome transition zone in recent decades is important to understanding the response of its ecosystem to climate change. Here, the annual vegetation phenology in the desert/grassland biome transition zone was deduced from the third generation NOAA/GIMMS dataset (GIMMS3g) and the spatiotemporal changes of phenology from 1982 to 2012 was studied. At the same time, the climatic driving factors of phenology change were also been analyzed by coupling globe meteorological reanalysis data. The study obtained the following results and conclusions:(1) The vegetation activity in different desert/grassland biome transition zone generally has the same tendency under the background of global climate change. However, because of the redistribution of moisture and heat in different regions, the change of vegetation activity has the opposite characteristics in individual regional.(2) From the point of vegetation change tendency and characteristics, the vegetation activity of global desert/grassland biome transition zone slowly increased before 1998; the vegetation activity began to abate in parts of desert/grassland biome transition zone and the spatial differentiation and fluctuation of the variation trend of NDVI increased after 1998.(3) Before and after the breakpoint (1998) of global climate, the vegetation phenology of desert/ grassland biome transition zone has sharp contrast characteristics between northern hemispheres and southern hemispheres. The vegetation phenology of the northern hemisphere is shorter after 1998 than before 1998 and the IOS (Integral of Growth Season) of NDVI decreased. In contrast, the vegetation phenology of the southern hemisphere is longer and the IOS (Integral of Growth Season) of NDVI increased.(4) Finally, the climatic driving factors of phenology change were also analyzed. The effects of evapotranspiration and precipitation on vegetation activity are most obvious. Temperature rising has inhibitory effect on vegetation activity in low latitude area and promoting effect in the middle and high latitude area. The effect of radiation on vegetation activity is the weakest and most of them show the negative correlation relationship. At the same time, the relationship between phenology and meteorological factors in different time-lags also been analyzed. The results show that the phenology change of desert/grassland biome transition zone is responsed immediately to temperature change and there has a time lag effect in the response of phenology change to evapotranspiration. In the meantime, there has a time lag effect in the response of EOS change to precipitation, but this rule does not exist between SOS change and it.