为了了解重庆石漠化地区植被恢复以及生态环境治理状况,选取重庆石漠化地区归一化植被指数(NDVI)及气象数据,利用趋势分析、变异系数分析以及偏相关分析等方法,重点探讨了重庆石漠化地区2005—2014年NDVI的时空变化特征,并分析了NDVI变化与气候因子之间的相关性。结果 表明:(1)重庆石漠化地区NDVI年际变化总体上呈增加趋势,增加速率为0.08/10 a,其中渝东北地区增长速率相对较高,达0.09/10 a,而NDVI季节变化存在一定差异性,春季增长最为显著,主要分布于渝东北、渝中和渝西地区;(2)渝东北石漠化地区NDVI呈增加趋势的区域范围较大,这对于三峡库区生态环境改善以及水土保持起着至关重要的作用; 渝东南、渝中和渝西石漠化地区NDVI整体保持不变,而NDVI呈减小趋势的区域主要分布于乌江流域;(3)重庆石漠化地区2005—2014年NDVI变异系数相对较低,以稳定为主;(4)重庆石漠化地区降水和气温分别与NDVI之间正相关性都大于负相关性。总体上降水量的增加一定程度促进了三峡库区植被的生长,而温度的降低一定程度上抑制了乌江流域植被的生长。
In order to understand the restoration of vegetation and the treatment of ecological environment in rocky desertification areas of Chongqing City, NDVI and meteorological data from 2005 to 2014 in rocky desertification areas of Chongqing City were selected, and trend analysis, variation coefficient analysis, partial correlation analysis and other methods to focus on the spatial-temporal variation of NDVI in the rocky desertification areas of Chongqing City over the past 10 years were used, and the correlations between the NDVI and climatic factors were analyzed. The results show that:(1)the interannual variation of NDVI shows an overall increasing trend in rocky desertification areas of Chongqing City, with an increasing rate of 0.08/10 a. Among them, the growth rate in northeast Chongqing City is relatively high, up to 0.09/10 a, and the seasonal variation of NDVI has some differences, and the spring growth is the most significant, mainly distributed in the northeast, central and western regions of Chongqing City;(2)the area with increasing NDVI in the northeastern Chongqing has a large area, which plays a crucial role in improving the ecological environment and soil and water conservation in the Three Gorges reservoir area; the NDVI in the rocky desertification regions of southeastern and midwest Chongqing City remained as a whole, but the areas with decreasing NDVI were mainly distributed in the Wujiang River Basin;(3)the coefficient of variation of NDVI in rock desertification of Chongqing City from 2005 to 2014 was relatively low, and the degree of variation was mainly stable;(4)the positive correlation between precipitation and NDVI in rocky desertification areas of Chongqing City is larger than that of negative correlation, the same to the positive correlation between temperature and NDVI. In general, high-humidity environment promoted the growth of vegetation in the Three Gorges reservoir area to a certain extent, while the low-temperature environment has inhibited the growth of vegetation in the Wujiang River Basin.
(1)
(2)
为地区逐渐NDVI平均值; Cv值越大表明变异程度较高,Cv值越小表明变异程度较低; 为了较好地分析10 a间重庆石漠化地区植被的变异程度,本文将其划分为4个等级,分别为非常稳定(Cv≤0.04)、稳定(0.04<Cv≤0.08)、变异较小(0.08<Cv≤0.12)、变异剧烈(Cv>0.12)[4]。
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为研究时段内NDVI多年均值;
为研究时段内气温或降水量多年均值。
(4)
