大巴山地区植被覆盖变化及其对气候变化的响应

利用1998—2009年的SPOT VGT-NDVI逐旬数据集,对大巴山地区植被覆盖变化及其对气候的响应进行了研究。结果表明:(1)1998—2009年大巴山地区植被NDVI值变化整体呈显著上升趋势,年平均NDVI值在0.54～0.64之间;大巴山弧形褶皱带植被NDVI值较高,河流附近NDVI值较低;大巴山地区植被覆盖呈显著性增加趋势,在县城城区附近有植被退化迹象,占总面积的0.24%。(2)1998—2009年,提取6种植被类型的NDVI值在四季的变化总体呈上升趋势,尤其是春季NDVI变化显著;不同类型的植被NDVI值大小顺序为:阔叶林>针叶林(冬季为针叶林>阔叶林)>灌丛>草甸>草丛>栽培植被,其中,草甸在四季的变幅最大。(3)在时间尺度上,NDVI与同期、前一个月、前两个月的气温呈极显著相关性,与降水量的相关性不显著。空间尺度上,6月月均NDVI与气温呈负相关的像元数占67%,表明该时段温度升高可能导致蒸发量增大,从而抑制了植物生长。

Response of Vegetation Cover Changes to Climate Change in Daba Maintains

This paper studied vegetation cover variations and the response of vegetation changes to climate change in Daba Mountains from 1998 to 2009 based on SPOT-NDVI data.The result as follow:(1) The vege-tation cover has a significant increasable trends as a whole in Daba Mountains during 1998 to 2009,the value of annual NDVI is between 0.54 and 0.65,the NDVI value is higher in mountains,and lower near the river in space;The major area of vegetation cover had undergone changed in last decade,and the result has through the significant test.The sign of vegetation degradation distributed near the city,for the total area of 0.24%.(2) During the past 12 years,six types of vegetation cover tended to growth in significantly in seasons,especially in the spring.Beginning with the largest,the NDVI values of different vegetation types is broad-leaved forest,coniferous forest(the values is coniferous forest>broad-leaved forest in winter),shrub,meadow,grass and planting vegetation,which meadow of the amplitude maximum.(3) In the scale of time,the NDVI value showed significant correlation with temperature of current month,the previous month and two months before the current month.The pixels of average NDVI value in June which are negatively correlated with the temperature account for 67% of the total,which showed that the rise of temperature could lead to the increase of evaporation,thus restrain the growth of plants.