2000—2018年乌海市植被覆盖度时空变化

为了探究乌海市植被覆盖度时空动态变化特征以及预测NDVI变化趋势,基于Lantsat OLI/TM/ETM,DEM影像运用像元二分模型法、趋势分析法研究了乌海市2000—2018年植被覆盖度时空动态变化特征,重标极差(R/S)分析法的Hurst指数预测了乌海市未来NDVI变化趋势。结果表明:(1)2000—2018年乌海市植被覆盖度整体呈现上升趋势,增长速率为0.07%/10 a,植被覆盖度均值由22.26%增至41.30%;(2)空间上植被覆盖度呈现由西北向东南逐渐递增的趋势,植被覆盖度改善的区域大于退化区域,海南区改善趋势更明显;(3)从地形因子来看,植被覆盖度受高程、坡度影响较大,不同坡向间变化不明显;(4)乌海市大部分地区植被未来变化趋势为随机发展,持续改善区域占10.95%,持续退化区域占2.93%,海勃湾区持续变化性强,乌达区反持续变化性强。整体来看研究区2000—2018年植被覆盖度持续上升,植被改善明显,未来进行生态保护时应多关注地形因素和植被退化的区域,从而制定合理的政策。

Spatiotemporal Variation of Vegetation Coverage in Wuhai City from 2000 to 2018

In order to explore the characteristics of temporal and spatial dynamic change of vegetation coverage in Wuhai City and forecast the trend of NDVI in the future,based on Lantsat OLI/TM/ETM,DEM images were used to study the characteristics of temporal and spatial dynamic change of vegetation coverage in Wuhai City from 2000 to 2018 by using binary pixel model and trend analysis method.The Hurst index of R/S analysis method was used to predict the future NDVI trend in Wuhai City.The results show that:(1)from 2000 to 2018,the vegetation coverage in Wuhai City showed an increasing trend,with an increasing rate of 0.07%/decade,and the mean FVC increased from 22.26%to 41.30%;(2)the spatial FVC increased gradually from northwest to southeast,and the improved area of FVC was greater than the degraded area,and the improvement trend was more obvious in Hainan;(3)from the perspective of topographic factors,the vegetation coverage was greatly affected by elevation and slope,and the change between different slope aspects was not obvious;(4)the future change trend of vegetation in most areas of Wuhai City is random development,the area of continuous improvement accounts for 10.95%,and the area of continuous degradation accounts for 2.93%;Haibwan District has strong sustainable change,and Wuda District has strong anti-sustainable change.On the whole,vegetation coverage in the study area continued to rise from 2000 to 2018,and vegetation improved significantly.In future ecological protection,more attention should be paid to topographic factors and areas with vegetation degradation,so as to formulate reasonable policies.