基于RS和GIS的青海湖流域植被覆盖度变化与驱动因子研究

Study on Changes of Vegetation Fraction and Its Driving Factors in Qinghai Lake Basin Based on RS and GIS

基于2001—2010年MOD13Q1数据,采用像元二分模型估算近年青海湖流域的植被覆盖度,分析其时空变化规律,探讨植被覆盖度与气象因子、地形因子之间的关系。结果表明:在青海湖流域,年平均植被覆盖度呈中部高、西北低的态势,中高覆盖度面积最大,占流域总面积的60%以上;近10年流域平均植被覆盖度呈波动上升趋势,最大值出现在2010年;NDVI在年际尺度上与气温的相关性并不显著,但与降雨量呈显著正相关关系(R=0.79),降雨量与植被覆盖度年际变化总体趋势较为相似;植被覆盖度随高程和坡度的增大均先增大后减小,最大值出现在海拔3500—4000m、坡度2°—6°的缓平地上;阳坡的植被覆盖度大于阴坡,而平地最小。

Using MOD13Q1 and climatic from 2001-2010 and DEM dataset of Qinghai Lake Basin were analyzed vegetation fraction changes and the correlation with driving factors. The results showed that： The vegetation fraction was high in Qinghai Lake Basin,more than60% with high and middle vegetation fraction. And the distribution characteristic was middle part high and northwest part low. Over the ten years,the overall trend of vegetation coverage in Qinghai Lake Basin was on the rise,and the highest had reached 65. 89% in 2010. The correlation of NDVI with temperature was not significant in the interannual scales,while the precipitation showed a significant correlation,showing a correlation coefficient of 0. 79. And changes in vegetation fraction in the ten years were essentially consistent with changes in precipitation. The spatial difference of the vegetation fraction was closely related with terrain. The vegetation fraction first increased and then decreased with the increment of altitude or slop. The highest distribution of vegetation fraction was at the altitude of 3500-4000 m and the slop was of 2°-6°. The vegetation fraction decreased in the order of sunny slop,shady slop and flat land.