西北地区植被覆盖时空特征及其对气候变化的响应

目的定量分析西北地区地表植被覆盖的时间变化与空间分布,为其合理开展农业生产,进行环境保护和生态建设提供科学的决策依据。方法利用西北地区1982—2006年GIMMS-NDVI数据,以绿度变化率和偏相关分析法为基础,分析了西北地区不同生态地理分区NDVI的年际变化以及植被覆盖变化对气候要素在空间上的响应。结果近25年来,高原植被覆盖整体呈波动增加的趋势。各生态分区的NDVI均呈增长趋势,并且随着湿润程度和温度的降低,年均NDVI随之减小;1982—2000年降水量在减小,但减小幅度不显著;气温呈显著上升趋势,年均NDVI与气温的相关性较好。结论西北地区的东南部和西北部地区水热组合条件相对于中部地区较好;植被覆盖较好的区域,其改善的趋势明显,相反则不明显;西北地区东部水热组合条件向不利于植被生长方向转变,而西部向利于植被生长的方向发展。

Spatial-temporal pattern of vegetation coverage in Northwest China and its response to climate change

Aim Northwest China is a sensitive zone of climate change in China.In this way,quantitative analysis of temporal change and spatial distribution of ground vegetation coverage offers a scientific decision basis for its reasonable agricultural production,environmental protection and ecological construction.Methods By using Northwest China′s GIMMS-NDVI data 1982—2006,annual variation of NDVI in different eco-geographical regions of Northwest China was put under analysis,with research into spatial response of vegetation coverage change to climate factor on the basis of greenness rate of change(GRC) and partial correlation analysis.Results In recent 25 years,plateau vegetation coverage increased in a fluctuating way on the whole.NDVI in all the regions shows a growth trend,with decreasing annual average NDVI as wetness and temperature decreases.Variation rate of annual precipitation 1982—2000 showed a slightly decreasing precipitation;air temperature was significantly higher year by year.There is good correlation between YMNDVI and air temperature.Conclusion Southeast and Northwest of Northwest China own better combined water-heat conditions than the central area.Combined water-heat conditions of East in Northwest China are to the disadvantage of changing in vegetation growth direction,but converse in the West.Areas with good combined water-heat conditions are mainly distributed in the East of Northwest China.