以20022015年夏季的MODIS NDVI数据(250 m * 250 m分辨率)、青海省DEM数据和青海省夏季逐月气象数据为基础,利用像元二分法估算青海省14 a间的植被覆盖度,通过空间插值方法、空间相关分析、统计学方法分区、分级对其时空变化特征和驱动因子进行分析,结果表明:近14 a来青海省高、中植被覆盖区面积呈增加趋势,而植被低覆盖区面积呈减小趋势。从分区来看,环青海湖祁连山区植被覆盖面积呈减小趋势,其余3区均呈增加趋势。从分区分级来看,东部黄土高原区和环青海湖祁连山区的植被高覆盖区、青南高原植被低覆盖区面积呈减小趋势,其余各区各级植被覆盖区面积均呈增加趋势。与水热条件的空间相关分析显示,青海省东部和东南部与温度的正相关性相对显著;柴达木盆地东缘、南缘,青南高原的大部分地区与降水的正相关相对显著;青海省东部与降水呈正相关,但相比于温度相关性较弱。从驱动因子来看,柴达木盆地植被高、中覆盖区,环青海湖祁连山区的植被中覆盖区面积变化受温度和降水的共同驱动;青南高原区子区的干旱区植被中、高覆盖区,半干旱区植被低覆盖区,半湿润区植被中、低覆盖区面积变化受温度和降水的共同驱动;半干旱区中、高植被覆盖区面积变化受降水驱动,半湿润区植被高覆盖区和湿润区植被高、中、低植被覆盖区面积变化受温度驱动;东部黄土高原区子区中山区植被中、高覆盖区面积变化受降水和气温共同驱动,山区植被低覆盖区面积变化受降水驱动。
英文摘要:
In this paper, the values of VFC in Qinghai Province in 14 years were estimated with the method of dimidiate pixel model by using the climatic data from 47 meteorological stations in the province during the period of 20022015 and the MODIS NDVI data of 16-day composite (250 m * 250 m resolution) as well as many other scientific methods, such as spatial analysis and correlation analysis,and the paper studied the vegetation average distribution and its evolution along with climate change in the 14 years in Qinghai Province and its four subregions including the Qaidam Basin, loess plateau in the east,Qinghai Lake - Qilian mountain and pastoral area in the south. The results showed that the distribution of vegetation in the province was obviously different from different regions. The regions with high vegetation coverage were mainly distributed over the southeast of pastoral area in south Qinghai and around the Qinghai Lake. The regions with moderate vegetation coverage were mainly distributed in the north of pastoral area in south Qinghai and the loess plateau in the east. The regions with low vegetation coverage were mainly distributed over the Qaidam Basin. In the recent 14 years,holistically, the area of the regions with high and moderate vegetation coverage was in an enlarged trend,but that with low vegetation coverage was reduced. Moreover, the areas of the regions with high vegetation coverage around the Qinghai Lake - Qilian Mountain and the loess plateau in the east,with low vegetation coverage in pastoral area in the south,and with high vegetation coverage in the Qaidam Basin were in a reduction trend by rates of 0.94%,0. 58%,0. 92% and 2.78% respectively,and those in other regions were enlarged. There was no significant influence of rainfall and temperature changes on the low vegetation coverage. The area change of the regions with high and moderate vegetation coverage in the Qaidam Basin and with moderate vegetation coverage in the Qilian Mountains was affected by temperature and rainfall. In the subzone of the southern Qinghai Plateau, the area change of the regions with moderate and high vegetation coverage in arid zone,with low vegetation coverage in semiarid area and with low coverage area in semi-humid area was affected by temperature and precipitation; the regions with high vegetation coverage in semiarid area was influenced by rainfall; the area change of the regions with high vegetation coverage in semi-humid and humid areas and with low and moderate vegetation coverage in humid area was affected by temperature. The area change of the subzones with moderate and high vegetation coverage in the east loess plateau and in a mountain area was affected by temperature and precipitation, that with low vegetation coverage by precipitation,and that in the river valleys was mainly affected by human activities.