祁连山黑河流域NDVI时空变化及其对气候因子的响应

Spatial and temporal variations of NDVI and its response to meterological factors over Heihe River basin of Qilian Mountains

基于GIS和RS技术,利用SPOT-VGT(NDVI)数据和黑河流域15个常规气象站及自动气象观测站的气温.降水量、不同深度的土壤温度、体积含水量等资料,系统分析了黑河流域NDVI的变化特征及其对气候因子的响应特征.通过年平均累积和趋势线分析方法,得出1999-2011年黑河流域NDVI的时空分布特征:年累计NDVI和年均NDVI绝大部分处于增长趋势,只有下游的西部和上游的南部一些地区处于降低趋势;季节累积NDVI和季节平均NDVI绝大部分区域处于增长趋势;在植被退化的阶段,冬季植被退化较其他季节严重;在植被增长的阶段,秋季植被增长较快.通过数理统计方法分析了NDVI对气象因子的响应关系:土壤温度对NDVI的关系能够较好地拟合NDVI的发展趋势,NDVI对气温和降水量的滞后时间大约分别为2旬、1个月,春季NDVI受到前一年11月份和秋季降水量影响较大,总体上土壤水分对NDVI影响较复杂.

Based on GIS and RS technology, the SPOT-VGT NDVI, temperature, precipitation, ground temperature and volume of soft moisture content at differeut depths in 15 meteorological stations aud automatic observing stations in Heihd RiVer basin were used to analyse the character of NDVI variations and their response to the meteorological factors. By using the annual cumulative average method and trend line analysis method, the distribution character of spatial and temporal variations of NDVI in the Heihe River basin between 1999 and 2011 was determined. In general, there was a increasing tendency of annum cumulative average NDVI and mean yearly NDVI in most of the area, while the western down-stream and southern up-stream areas were decreasing. Seasonally cumulative NDVI and seasonally average NDVI were of an increasing tendency. In the decreasing stage, vegetation deterioration in winter was more serious than other seasons. In the increasing stage, vegetation in autumn increased faster than in other seasons. Mathematical statistic methods were used to analyse the NDVI response to the meteorological factors： it could simulate the tendency of NDVI changing when the ground temperature was taken into account; the delay time of NDVI response to the air temperature and precipitation was about two dekans and one month respectively, the NDVI in spring was more affected by the November and autumn precipitation in the previous year and the soil moisture responses to NDVI was of a complicated nature.