2000～2017年贵州省植被覆盖时空变化特征及其对气候变化的响应

利用MODIS/NDVI数据、近18年来贵州省气象站点数据,辅以时间序列、变化趋势和空间动态变化分析等方法,研究贵州省植被覆盖的时空变化特征;探讨植被覆盖变化对气象因子在地域、变化速率和变化方向方面的时空响应规律。研究结果显示：（1）2000~2017年贵州省植被覆盖呈现显著增加的趋势,增速为0.004/a,夏季NDVI值最高,冬季增加趋势最大;空间上,贵州省植被覆盖格局呈现"南高北低、东高西低"的空间分布特征。在变化趋势上,贵州省植被覆盖呈改善和退化趋势的面积分别占贵州省总面积的94.97%和5.03%。（2）2000~2017年,贵州省气候变化特征是降雨量在年内分布不均,且主要分布在5月至8月;温度在各个季节变化趋势不明显,但是总体呈上升的趋势。气温和降水变化趋势大于零的面积分别占贵州省总面积的98.4%和60.46%,说明在全球暖湿化的大背景下,贵州省大部分地区亦呈温度升高、降水增加的态势。（3）贵州省NDVI与气温的相关性大于降水,但其对降水的滞后性却高于气温。其中,秋季植被受降水影响滞后性最强,其次是夏季。（4）不同气候要素对贵州省植被生长影响具有空间差异性,98.4%的地区NDVI与同期温度均达到正相关水平;NDVI与同期降水并未表现出良好的相关性,但82.63%的地区植被与前一年降水呈正相关水平。植被与降水呈负相关的地区,建设用地、裸地占更大比率,且人类活动在植被变化中的作用不容忽视。

Spatiotemporal Variation of the Vegetation Coverage in Guizhou from 2000 to 2017 and Its Response to the Climate Change

Based on MODIS/NDVI data and regional meteorological observations in the past 18 years, this study analyzed the responses of spatiotemporal variation characteristics of vegetation coverages in Guizhou to regional change direction and rate of meteorological factors. The results were shown as follows:(1) The comparison of NDVI images showed that vegetation coverages in Guizhou increased significantly at a rate of about 0.004/a from 2000 to 2017. The highest NDVI values happened in summer and the largest increase trend happened in winter. Spatially, vegetation coverages were higher in south and east regions and lower in north and west regions of Guizhou. In terms of the change trend, the area of improved or degraded vegetation coverage occupied 94.97% or 5.03% of the total area of Guizhou, respectively. (2) The climate of Guizhou can be characterized by the uneven precipitation, which concentrates in the period of from May to August, and the insignificant seasonal temperature variation, however, during the period of 2000 to 2017, the precipitation and temperature of Guizhou showed an overall trend of increase, for example, areas with increasing temperature and precipitation were about 98.4% and 60.46% of the total area of Guizhou, respectively, indicating that, in the context of global warming and humidification, the most region of Guizhou had experienced the increases of both temperature and precipitation. (3) Generally, NDVI of Guizhou showed a better correlation with temperature than with precipitation and a higher hysteresis with precipitation than with temperature, the time-lag between vegetation and precipitation was strongest in autumn then in summer. (4) The effects of different climatic factors on the vegetation growth varied spatially in Guizhou, NDVI values in 98.4% study area showed a positive correlation with temperature but precipitation in the same year, whereas NDVI values in 82.63% study area showed a positive correlation with precipitation of the previous year. Construction land and bare land dominated the areas whose NDVI values correlated negatively with precipitation. Hence, the role of human activities in vegetation changes cannot be ignored.