宁夏近20年来植被覆盖度及其与气温降水的关系

利用1981—2004年的植被指数(NDVI)资料,结合实地植被调查资料,将宁夏植被类型划分4个区域,确定了各地植被指数与覆盖度的关系,分析了宁夏各区域植被覆盖度的年际变化、季节变化、植被覆盖度的面积变化及其与气温和降水量的关系。结果表明:24年来宁夏贺兰山与贺兰山东麓的年植被覆盖度呈下降趋势,中部干旱带植被覆盖度呈上升趋势;近4年来,贺兰山植被状况整体变好;贺兰山东麓植被状况整体变差;中部干旱带的植被状况夏季变差,秋季变好;南部山区的植被覆盖度整体变好。宁夏春夏季降水量是影响植被覆盖度的关键性因子,气温对植被覆盖度的影响不显著。

Vegetation coverage and its relationships with temperature and precipitation in Ningxia in 1981-2004

Based on the 1981-2004 NDVI(Normalized Difference Vegetation Index)data and the survey of ground vegetation,the vegetation types in Ningxia were divided into four regions,and the relationships between vegetation index and vegetation coverage were identified.The inter-annual,seasonal,and area changes of the vegetation coverage in the four regions,as well as the relationships of these changes with temperature and precipitation were analyzed.The results showed that since 1981,the vegetation coverage in Helan Mountain and its eastern foot had a decreasing trend,while that in central arid region was in adverse.Overall,the vegetation coverage in the recent 4 years turned better in Helan Mountain but worse at its eastern foot,better in autumn and worse in summer in central arid region,and better in southern mountain region.The precipitation in spring and summer was the key factor affecting the vegetation coverage in Ningxia,while temperature had less effect.