基于SPOTVEG NDVI和降水序列的退耕还林（草）效果分析

基于陕西省榆林、延安、西安和安康4市1998-2005年SPOTVEGNDVI月数据和月降水序列的关系分析,利用NDVIC(剔除降水量对NDVI的影响)指标对退耕还林(草)工程效果进行了分析。结果表明:①NDVI和降水量(当月与上月降水量的平均值)间存在明显的相关性(R=0.27~0.82),且随着纬度的增高,相关系数增大;②以延安为例,1999-2005年植被覆盖率显著上升,尤其是2002-2005年,这主要与气候条件(降水)变化和土地利用变化有关;③1999-2005年10月NDVIC显著增加,是退耕还林(草)工程实施效果的客观反映。本研究可为客观地定量评价退耕还林(草)工程效果提供思路。

Analysis of effects of "Grain for Green" program using temporal NDVI and rainfall series

In this study NDVIC,assigned as the NDVI value in an effort to eliminate the influence of rainfall,based on time series of rainfall data and temporal SPOTVEG NDVI data,was used to evaluate the effects of "Grain for Green " project for the period 1998-2005 in Yulin,Yan'an,Xi'an and Ankang of Shaanxi Province.A strong relationship existed between rainfall and integrated NDVI(monthly) for all four sampling domains(R = 0.27 to 0.82),while the correlation coefficient increased from south to north.Vegetation coverage has increased in Yan'an from 1999 to 2005,especially in 2002-2005,showing some correlation with the climate variables,especially rainfall(1 month time-lagged),but precipitation alone don't fully explain the increased green cover.Increased NDVIC in October expresses an obvious effect of GFG on the vegetation change.It provided a thought for objective and repeatable evaluation of effects of "Grain for Green" program.