长江流域NDVI对气候变化响应的时滞效应

利用1982-2006年GIMMS NDVI数据和气象站点资料,结合中国地形的三大阶梯分布,分析长江流域植被NDVI时空变化特征及其对气候变化响应的时滞效应.结果表明,长江流域植被覆盖变化空间差异显著,其中显著增加区域占总面积的18.22％,主要分布在“第一阶梯”和“第二阶梯”；显著减少的区域占总面积的8.72％,主要分布在“第二阶梯”和“第三阶梯”.在时间上,长江流域植被总体上对气温变化的响应程度大于降水,植被对气温变化最大响应无滞后,对降水变化的最大响应滞后1个月.春季植被对气温变化响应最大,秋季植被对降水变化响应最大,夏季植被对气温和降水的最大响应滞后期较长.在空间上,植被对气温和降水的最大响应表现为“第一阶梯”最显著,对应的最长滞后期则分别出现在“第一阶梯”和“第三阶梯”.另外,由于山脉的阻隔作用,导致在地形阶梯间高程突变线左右两侧,NDVI对气温和降水变化的最大响应程度存在高处明显大于低处的现象.

Time Lag Effect of NDVI Response to Climatic Change in Yangtze River Basin

Combined the three ladder distribution of China, authors analyzed the spatio-temporal variations of vegetation NDVI and its responses to the variations of temperature and precipitation in month scale, based on the GIMMS NDVI datasets and month temperature and precipitation data from meteorological stations in Yangtze river basin during 1982 to 2006. The results showed that there were significant spatial differences of Yangtze river basin vegetation. The significant increased area was accounted for 18.22% ,which mainly distributed in the first step and the second step,while the significant decreased area was accounted for 8.72% and mainly distributed in the second and third step. Analyzed on the time, found that the response of NDVI to the variation of temperature was greater than to that of precipitation, the maximum response of NDVI to temperature changing without delay, while the maximum response of precipitation delayed one month, spring vegetation was responded most to temperature and fall vegetation was responded most to precipitation, the lag time of summer vegetation responded to temperature and precipitation was longer than other seasons. Analyzed on the space, found that the most significant response of vegetation to temperature and precipitation was occurred in the first step, and the longest lag time respectively occurred in the first step and the third step. Moreover, because of the effect of mountain barrier, the area from the first step to the second step and the second step to the third step, the maximum response of vegetation NDVI to the variation of temperature and precipitation of higher place was significantly greater than that of lower place.