甘肃省植被覆盖时空变化趋势研究

Study on Spatial and Temporal Variation Trend of Vegetation Cover in Gansu Province

利用SPOT NDVI和DEM数据,采用方差法、变异系数法、回归分析法、像元二分模型法和地形因子的方法对甘肃省1999~2018年20年间的植被覆盖度(VFC)时空变化特征进行了分析。结果表明:从时间尺度上来看,1999~2003、2004~2008、2009~2013、2014~2018年4个时间段的回归系数K>0,月方差、月标准差、月变异系数在逐渐变大,表明植被覆盖度的月变化呈增长趋势。且其趋势与植物的物候特征基本一致;从空间尺度上来看,植被覆盖度整体上呈东高西低、南高北低的分布状态且存在地域差异性,易受外界环境影响;从地形因子坡度和坡向上来看,植被覆盖度受坡度的影响较大,受坡向的影响较小,高坡度地区易发生水土流失现象。

The SPOT NDVI and DEM data were used in the paper.The temporal and spatial variation characteristics of vegetation coverage(VFC)in Gansu Province during the 20 years from 1999 to 2018 were analyzed by means of the variance method,variation coefficient method,regression analysis,binary model and the method of terrain factors.The Results showed that the four periods of regression coefficient K was>0 from the point of time scales,1999~2003,2004~2008,2009~2013 and 2014~2018.Variance,standard deviation,variation coefficient of monthly was bigger,The results showed that the monthly change of VFC showed an increasing trend,which was basically consistent with the phenological characteristics of plants.From the point of spatial scales,the vegetation coverage on the whole was high in the east and low in the west,high in the south and low in the north,and there were regional differences,which were easily affected by the external environment.Upward from the terrain factor,slope and slope,the vegetation coverage was greatly affected by the slope,and was less affected by the slope direction.Therefore,soil and water loss was easy to occur in high-slope areas.