南方丘陵区植被覆盖度遥感估算与时空变化研究——以福建省永定县为例

植被覆盖度是生态环境监测的重要指标,而复杂地形因素影响对山地植被遥感信息准确提取。基于Landsat-8OLI遥感数据,分别采用像元二分模型和线性混合光谱分解法,在对比分析植被覆盖度的地形敏感性基础上,选择山地植被指数(NDMVI)估算了1992、2002和2014年永定县的植被覆盖度,并分析其变化。结果表明:1基于山地植被指数(NDMVI)的覆盖度估算模型的地形敏感性最弱,更适合于南方丘陵山地的植被覆盖度遥感反演;2永定县总体植被覆盖度较高,平均植被覆盖度达77.99%以上,高覆盖度区占59.73%以上,22年内植被覆盖度经历了先提高再下降的过程;3在空间上,高坎抚、金丰和西部片区的植被覆盖度较低,动态变化较明显。永定县金丰片区植被覆盖度明显提高;而近12年内高坎抚片区因矿业开采活动对生态环境的破坏,植被覆盖度降低幅度大,且变化面积较大。

Estimation of Fractional Vegetation Cover and Its Spatial-temporal Variation in Hilly Area of Southeastern China:Yongding County,Fujian Province

Fractional Vegetation Cover (FVC) is a vital indicator for ecological environment monitoring.However it is quite difficult to obtain the high|accuracy FVC in the mountainous regions,especially in southeastern China,due to the topographic effects.In this research,a mountainous area in Yongding county Fujian Province was selected as study area,and Landsat|8 OLI was employed for the FVC retrieval.In order to choose a suitable model for the FVC retrieval in this area,the Dimidiate Pixel Model(DPM) and the Linear Spectral Mixture Analysis(LSMA) were performed to quantitatively evaluate the effects of mountainous topography.Then,the Normalized Difference Mountain Vegetation Index(NDMVI) was selected to calculate the FVCs of Yongding county in 1992,2002 and 2014,respectively.The results show that the model using NDMVI is found to be the less sensitivity in the hilly areas after testing the four models for retrieving FVC,and it is quite suitable for retrieving FVC in southeastern China.What’s more,the average value of FVC in Yongding county is greater than 77.99%,and more than 59.73% of the county are cover with high-density vegetation.Additionally,The FVC increase markedly during the period from 1992 to 2002,and decrease from 2002 to 2014.Some special regions such as Gaokanfu,Jinfeng and the west of Yongding county are cover with relatively low|density vegetation and change obviously during these years.And the values of FVC are greater than before in Jinfeng region,but the vegetation are seriously damaged by mining in Gaokanfu region and the FVC are quite smaller in last 12 years.