肯尼亚蒙内铁路区域植被覆盖度时空变化分析

Analysis of temporal and spatial changes of vegetation coverage of the Mombasa-Nairobi railway area in Kenya

通过分析长时序MODIS-NDVI数据,得到2000-2017年的植被覆盖度(Fractional Vegetation Cover,FVC),使用相关性分析、变异程度分析等方法对肯尼亚蒙内铁路区域植被覆盖度进行时空变化分析.结果表明:①2000-2017年研究区域FVC值总体呈增加趋势,增速为0.02%/10 a;2013-2017年蒙内铁路修建期间该区域FVC值缓慢上升,从74.82%上升到了76%.②FVC的总体特征为内罗毕国家公园、察沃国家公园以及蒙巴萨周边低海拔区域植被覆盖度较高,FVC值保持在80%左右;蒙内铁路中段车站等中小城市的FVC值较低,在60%以下.根据2000-2017年FVC值稳定性表现为面积增加占44.04%,稳定占52.45%,减少趋势占3.51%.③2000-2008年时段,面积转移矩阵比值为0.87,表现出轻度的减少,2009-2013年和2014-2017年2个时间段比值均>1,表现出植被覆盖度(FVC)有改善的趋势.

Forest vegetation coverage(FVC)from 2000 to 2017 was obtained by analyzing long-term MODIS NDVI data.Analytical methods such as correlation analysis and variation degree analysis were used to analyze the temporal and spatial changes of vegetation coverage of the Mombasa-Nairobi railway area in Kenya.The results show:①The relevant regional FVC shows an increasing trend from 2000 to 2017,with a growth rate of 0.02%/10 a.During the construction of the Mombasa-Nairobi railway in 2013-2017,the FVC in the region increased slowly,from 74.82%to 76%.②The overall characteristics of the FVC are higher vegetation coverage in the Nairobi National Park,Tsavo National Park,and the low-altitude areas around Mombasa:the FVC is around 80%.And the FVC in small and medium-sized cities along the mid-section of the Mombasa-Nairobi railway is lower,below60%;the stability value of FVC from 2000 to 2017 demonstrates that:it increased in 44.04%of the relevant regions;it was stable in 52.45%;and it showed a decreasing trend in 3.51%.③The ratio of the area transfer matrix of the period from 2000 to 2008 showed a slight decrease.The ratio of the two periods from 2009 to 2013 and 2014 to 2017 was greater than 1,showing an improvement in FVC.