长江上游植被覆盖的时空分异季节变化及其驱动因子研究

The spatial-temporal distribution of seasonal vegetation changes and their driving forces in the upper reaches of the Yangtze River

以GIMMS/NDVI为基础,结合气候与人类活动数据,研究了1982～2003年间长江上游植被覆盖季节变化的空间分布.结果表明,近22年来,长江上游春季、夏季植被覆盖呈增加趋势,以春季最显著;秋季、冬季植被覆盖呈降低趋势,以秋季降低最显著.春季、夏季降雨与气温的同步增加,致使植被覆盖增加;秋季降雨减少,以及气温的增加导致植被覆盖降低;另外,作物播种面积的增加是春季、夏季植被覆盖增加,秋季、冬季植被覆盖减少的重要原因.春季→夏季→秋季→冬季NDVI增加的区域在空间上大致呈现低纬度向高纬度转移的趋势.春季、夏季所有植被类型的NDVI均有增加趋势;而秋季所有植被类型的NDVI均降低;冬季植被除针叶林的NDVI略有增长外,其余植被类型的NDVI均降低.

Based on GIMMS/NDVI （Global Inventory Mndelling and Mapping Studies/Normalized Difference Vegetation Index） data from 1982 to 2003, the seasonal changes nf vegetation and their spatial patterns were explored. The results show that during the past 22 years the NDVI in the upper Yangtze River drainage basin increased in spring and summer, especially in spring; hut decreased in autumn and spring, especially in autumn. It was found that the temperature and precipitation increased synchronously in spring and summer, which resulted in an increase in the average spring and summer NDVI. The decrease of the average autumn NDVI can be explained by the decreased precipitation and temperature. Increased crop area was an important factor for the increased NDVI in spring and summer. When the crops were harvested, the NDVI decreased in autumn and winter. The areas with an increased NDVI shifted from low latitudes to high latitudes from spring to winter. The NDVI of all the vegetation types increased in spring and summer and decreased in autumn. In winter, the NDVI of all the vegetation types except coniferous forest decreased.