1999—2018年河南省植被覆盖时空演变分析

为了研究河南省植被覆盖的时空演变特征,利用slope趋势分析、典型地市分析、典型年份和月份分析、土地利用类型改变对植被覆盖的影响分析等方法,分析了1999—2018年河南省植被覆盖时空演变特征。结果表明:(1)河南省西部和南部植被覆盖改善十分明显,河南省北部和东部有轻微改善,而河南省中部植被覆盖有所退化;(2)河南省NDVI分布具有较强的空间差异性,从南北向来看,NDVI均值中部最低,南部最高,北部次之。从东西向来看,NDVI均值中部最低,东部最高,西部次之。河南省NDVI平均值在空间上呈现两头高中间低的趋势;(3)河南省月尺度的NDVI呈现出明显的季节性,最高值出现在夏季8月,最低值出现在冬季1月。(4)居民用地的增加影响着河南省的植被覆盖状况,并且呈负影响;(5)河南省自从实施“退耕还林”政策后,耕地明显减少、林地增多。由此可以得出,1999—2018年河南省总体植被覆盖率改善,NDVI值增加。

Spatiotemporal Evolution of Vegetation Cover in Henan Province from 1999 to 2018

In order to study the temporal and spatial evolution characteristics of vegetation cover in Henan Province,the temporal and spatial evolution characteristics of vegetation cover in Henan Province from 1999 to 2018 were analyzed by using the methods of slope trend analysis,typical city analysis,typical year and month analysis,and the impact of land use type change on vegetation cover.The results show that:(1)the improvement of vegetation cover in the west and south of Henan Province was obvious,there was a slight improvement in the north and east of Henan Province,while the vegetation cover in central Henan Province degraded;(2)the distribution of NDVI in Henan Province had strong spatial differences;from east to west,the NDVI average was the lowest in the middle,the highest in the east and the second highest in the west;the average of NDVI in Henan Province showed the trend of high in the surround areas and low middle part in provincial space;(3)the NDVI of monthly scale in Henan Province showed obvious seasonality,the highest value appeared in August in summer,and the lowest value appeared in January in winter;(4)the increase in residential land affected the vegetation coverage in Henan Province,and had a negative impact;(5)since the implementation of the policy of‘returning farmland to forest’in Henan Province,arable land had decreased significantly and forest land had increased.It can be concluded that the overall vegetation coverage of Henan Province had improved and the NDVI value had increased from 1999 to 2018.