Research On Vegetation Cover Change And Correlation With Climate Factors In Huanghe-Huaihe-Haihe River Basin

In this paper, the dynamic change and spatial distribution of vegetation cover in the Huanghe-Huaihe-Haihe river basin are analyzed based on NOAA/AVHRR-NDVI data from 1982 to 2003 by using the average value method, simple differencing, linear regression of one variable and principle component analysis techniques. And then together with climate data, we research the correlation of NDVI with the climate factors. This paper declares the characteristic of vegetation cover change and the correlation with climate factors. It does make sense to ecological environment protections and research in this area. Main conclusions are as follows:1) Vegetation cover of the research area trends to increase as a whole during 1982 to 2003 with a linear regression trend of 0.0007. Especially the average spring NDVI indicates the most significant increase (P＜0.001) with a linear regression trend of 0.0019. From the spatial distribution, the area which NDVI significantly increase is up to 26.41%, but the area which NDVI significantly decrease is only 1.86%. Therefore, in the past 22 years the vegetation cover of the research area exhibited rise trend.2) For different vegetation types, the annual mean NDVI all exhibit increase trend, except for some difference in range between them. Among them, crops one gathered from dry land and the other from paddy fields increases quickest with a linear regression trend of 0.0011. In spring, all vegetation types display general trend of rise over the research area. In summer, deciduous broadleaf, bushes, biannual crops and crops one gathered from dry land and the other from paddy fields trend to decrease, others trend to increase. In autumn, all vegetation types indicate rise trend except for biannual crops. Only evergreen conifer is included in winter which NDVI trends to rise. 3) Annual precipitation and temperature have positive correlation with dynamic NDVI variation. NDVI is correlated positively with temperature to greater degree with smaller correlation to precipitation, so the degree which vegetation sensitive to temperature is higher than that to precipitation.4) The area which NDVI has significantly positive correlation with temperature in spring and summer is up to 18.65% and 16.68%, but the area which NDVI has significantly positive correlation with precipitation is only 7.19% and 9.04%. In autumn, there are only some regions which NDVI has closely correlation with temperature and precipitation.