基于遥感技术的甘南牧区草地植被状况多年动态

Grassland vegetation dynamics over the years based on remote sensing technology in Gannan pastoral area

结合遥感技术的草地植被监测是区域植被变化研究的重要组成部分和研究热点,为了能够更好地监测甘南牧区多年的草地动态变化,本研究以甘南牧区的草地为研究对象,引入了垂直植被指数(Perpendicular Vegetation Index,PVI),探讨了其在甘南草地遥感监测中的适用性及其精度,并以草地植被盖度、草地面积和草地地上生物量为主要监测指标,对2001-2012年间甘南草地的变化做全面连续的研究,从草地的生态和资源属性两方面说明甘南草地的变化状况,期望为甘南牧区生态保护和畜牧生产提供帮助。结果表明,1)在运用MODIS数据对地表植被覆盖度进行估算时,使用归一化植被指数(Normalized Difference Vegetation Index,NDVI)的像元二分模型对植被覆盖度的模拟较垂直植被指数PVI更准确,其精度可达88.14%。2)盖度分级结果显示,植被盖度最大和最小分别为2010年的76.63%和2002年的73.21%,12年间的变异系数(Coefficient of Variability,CV)为1.25%,年际变化很小;3)对草地面积动态变化的研究结果表明,近12年平均草地面积占甘南州土地总面积的85.47%左右,且草地面积的年际变化较小。4)在高寒地区,垂直植被指数PVI的指数模型较NDVI能够更好地估算甘南州草地地上生物量,总体估产精度可达70.48%,且能很好地模拟整个生长季的生物量变化。

The monitoring of grassland vegetation based on remote sensing technology is an import branch and hotspot in regional vegetation change research.In order to precisely monitor grassland vegetation dynamic in Gannan,the present study monitors the dynamic change of Gannan grassland over 12 years from 2001 to 2012and also uses the Perpendicular Vegetation Index(PVI)to explore its applicability and accuracy in grassland monitoring of Gannan.These studies will provide references for livestock production and ecological protection in Gannan pastoral area.The results show that the Dimidiate pixel model based on normalized difference vegetation index(NDVI)can more accurately simulate the vegetation coverage change with a precision of 88.14%.The vegetation coverage results show that the vegetation coverage is maximum at 76.63%in 2010 and minimum at 73.21%in 2002 during the studied period.There is very little interannual variation in vegetation coverage with a variation coefficient of 1.25%.The average grassland area in these 12 years accounts for about 85.47% of the total land area in Gannan with little interannual variation.The Exponential function of PVI can more accurately simulate aboveground biomass in Gannan pastoral area with a mean precision of the monitoring models at 70.48%.