【摘要】 NDVI的时空变化可以反映区域生态环境的演变,基于像元尺度的趋势分析法能模拟研究区栅格单元的变化趋势,从而反映NDVI时空分布的变化细节。基于2000—2015年MODIS NDVI月时序数据,结合同期气象资料,利用趋势分析和相关分析的方法研究了渭河流域NDVI、气温和降水的时空变化特征及其相关性。结果表明:(1)近16年来,渭河流域平均NDVI呈增大的趋势,变化率约为0.088/10 a,植被覆盖度有所增加;NDVI增大的区域占流域总面积的97.77%,主要分布在流域西部和北部。(2)时间尺度上,NDVI与气温的相关系数为0.865,偏相关系数为0.664;NDVI与降水的相关系数为0.776,偏相关系数为0.346,表明气温和降水的季节变化对植被生长都具有重要影响,且气温的影响更为显著。(3)空间尺度上,NDVI与气温呈正相关的像元数占像元总数的51.21%,NDVI与降水呈正相关的像元数占像元总数的96.67%,表明就渭河流域而言,气温的变化对植被生长的影响具有空间差异性和不确定性,而降水的增加会促进植被的生长。更多还原

【Abstract】 The tempo-spatial changes of NDVI can reflect the evolution of regional ecological environment. On the basis of pixel scale, trend analysis method can simulate the trend of each grid cell in the study area, reflecting the detailed information of NDVI changes. Based on monthly data of MODIS NDVI from 2000 to 2015 and meteorological data of the same period, trend analysis method and correlation analysis method were used to study the tempo-spatial variation characteristics and correlation of NDVI, temperature and precipitation in the Weihe Watershed. The results showed that:(1) in the past 16 years, the average NDVI of the Weihe Watershed had increased, the rate of change was about 0.088/decade, and the vegetation coverage had increased; during the 16 years, the area of increasing NDVI accounted for 97.77% of the total watershed, these areas mainly distributed in the west and north of the watershed;(2) in the time series, the correlation coefficient between NDVI and temperature was 0.865, the partial correlation coefficient was 0.664; the correlation coefficient between NDVI and precipitation was 0.776, and the partial correlation coefficient was 0.346; it indicated that the seasonal variation of temperature and precipitation had a remarkable impact on vegetation growth, and the effect of temperature was more significant;(3) on the pixel scale, the area where NDVI was positively correlated with temperature accounted for 51.21%; the area in which NDVI was positively correlated with precipitation accounts for 96.67%. It indicated that there were spatial differences and uncertainty in the effects of temperature on vegetation growth, and the increase of precipitation mainly promoted the growth of vegetation.更多还原