基于地上净初级生产力与地上生物量的若尔盖高原放牧强度遥感监测

Remote sensing monitoring of grazing intensity in Zoige Plateau based on aboveground net primary productivity and aboveground biomass

若尔盖高原作为全国三大草原牧区之一,牧草资源丰富,但受放牧的影响,该地区的生态环境相继出现了湿地和草地的退化、土地沙化等现象。为准确、快速估测若尔盖区域尺度放牧情况,合理安排人类活动,为保护生态环境提供数据与理论支持,本研究利用MODIS-NDVI数据,结合地面实测数据及气象数据,分别模拟了地上生物量及净初级生产力(aboveground net primary productivity,ANPP),并在此基础上分析了2010−2019年若尔盖高原放牧强度。结果表明:模拟放牧强度的模型效果较好,R2值为0.7813,达到极显著相关水平(P<0.05),且均方根误差(root mean square error,RMSE)较小,精度可达到70%以上,能将不同放牧程度的区域区分开;若尔盖高原2019年平均放牧强度为1.87 AU·hm^(−2),处于过度放牧状态,且整体放牧强度呈现出东南部偏高、西北部偏低的分布态势。在时间变化上,若尔盖高原2010−2019年放牧强度整体呈增加趋势,在2010−2014、2014−2019年分别出现先增加后减少的变化过程;地上净初级生产力和地上生物量的分布态势与放牧强度的大小具有一定的关联性。

As one of the three grassland pastoral areas in China,the Zoige Plateau is rich in forage resources;however,owing to grazing,the plateau has suffered wetland and grassland degradation and land desertification.The aim of this study was to accurately and quickly estimate the grazing situation in the Zoige Plateau on the regional scale and provide data and theoretical support for the rational organization of human activities and protection of the ecological environment in this area.MODIS-NDVI,ground measured,and meteorological data were used to simulate the aboveground biomass and aboveground net primary productivity(ANPP)and evaluate the grazing intensity in the Zoige Plateau from 2010 to 2019.The model that estimated grazing intensity had a good effect on simulation of actual grazing intensity,with an R2 value of 0.7813,and reached an extremely significant correlation level with measured data of grazing intensity(P<0.05).Moreover,the root mean square error was small and the accuracy reached more than 70%;Thus,this model can distinguish regions with different grazing degrees.The average grazing intensity in the Zoige Plateau in 2019 was 1.87 AU·hm^(−2),which is a state of overgrazing,and the overall grazing intensity was higher in the southeast and lower in the northwest.Furthermore,the grazing intensity in the Zoige Plateau showed an overall increasing trend from 2010 to 2019,and increased first and then decreased during 2010−2014 and 2014−2019,respectively,and the distribution of ANPP and aboveground biomass was related to the grazing intensity to a certain extent.