Research On The Forcing Mechanism Of The LUCC And Vegetation Activity Of Qinghai Province In Short Temporal Scale Based On MODIS Images

Vegetation is the most marked land cover type in the terrestrial surface. Research on the interactive relationship between vegetation change and climatic factors is one of the important issues of the Global Change. This thesis took Qinghai province, China as reasearching target, analyzed the MODIS images and monthly meteorological records with the help of the RS & GIS platforms. After that, we combined the in situ measurements and documentary information to did preliminary research on the vegetation performance and changing trend of different land cover types in Qinghai province, 2000～2004. At last, some analyses on the relationship between vegetation and climate were discussed in depth. This thesis contains four main contents as follows:1,We employed the IDW, Linear regression, Ordinary Kriging, SKlm and Statistic algorithms to interploate monthly temperature and precipitation records of the 51 meteorological stations in and around Qinghai province from 1980 to 2004 separately. Then we found out the best-fit interpolators for the target, and established the spatially distributed temperature and precipitation model. After the validation, we found that Statistics performed best in all the five above interpolators when interpolating the monthly temperature, nevertheless, there is no uniform and best interpolators for the researching field when interpolating the monthly precipitation data. Based on the spatially distributed temperature and precipitation model, we established the target's vegetation-climate classification system.2,In accordance with the classification results of the MOD12Q1, we researched the land cover and land use change in Qinghai province from 2001 to 2004. The results indicate that land cover recovery can be the main changing trend of Qinghai province. However, the land in the west and north of Qinghai province maintained deteriorated. Through the analysis, we can also discover that in the arid and semi-arid region, northwest of China, which is dominated by one or several-year herbaceous vegetation, the land cover changed far more frequently than that in the east of China.3,Employing the MOD15A2 data instead of the common used vegetation index (VI), we analyzed the vegetation action of different land cover types in Qinghai province from 2000 to 2004, and we also calculated the length of the growing season according to the LAI value. The conclusions indicate that LAI value of the vegetation can also accurately illustrate the strength of the vegetation's performance. In addition, it can better describe the performance of the vegetation because of its wider valid value range.4,We analyzed the relationship between the vegetation activity in different land cover types and the temperature, precipitation in Qinghai province both in regional and grid scale. We found that the relationships between the LAI and the temperature, precipitation are obviously positive. Referring to the grid scale, the relationship is obviously negative between the LAI value and temperature in some regions of the southwest and south of the Qinghai province, we believe it could be partially influenced by the water loss because of more evaportranspiration caused by higher temperature.