基于遥感数据的呼伦贝尔草原放牧强度研究

A study of grazing intensity in the Hulunbuir grasslands using remote sensing

呼伦贝尔草甸草原是我国主要的畜牧业基地,放牧强度直接影响着该草原生态系统的稳定和可持续发展。本文首先建立了研究区草地地上生物量的遥感估算经验模型,然后结合净初级生产力(NPP),研究了草地放牧强度估算方法;基于该方法,利用2014年6月到7月多期Landsat遥感数据计算谢尔塔拉牧场草地地上生物量变化和放牧强度。研究结果表明:所使用方法可较好用于放牧强度的估算,估算结果与实际情况基本吻合,决定系数R2达0.7996;谢尔塔拉牧场的公共放牧区放牧强度范围为1~2.5Au/hm^2,属于过度放牧状态,重度放牧区多位于小型湖泊周围和草地面积较少但牛相对较多的生产队,轻度放牧区多位于围封地;将尺度扩展到海拉尔区分析:所使用方法能够准确地将轻度、中度和重度放牧区分开,且海拉尔区东北方向的放牧强度明显高于西南地区。

The Hulunbuir meadow steppe, located in northeast China, is an important site for animal husband-ry. The potential to further develop animal husbandry in this region is closely related to the growth of grass and to sustainable utilization of grasslands more generally. As a critical component of the grassland ecosystem, the intensity of grazing has become an important issue. In this study, remote sensing data, based on Landsat images, and Net Primary Productivity （NPP） data were collected from June to July 2014 and used to estimate grazing intensity in Xeltala pastures. Multi-image Landsat optical data was used to calculate aboveground bio-mass and biomass increments, while the NPP data was used to analyze grass growth. Unlike previous studies, this analysis used NPP data to take account of the heterogeneity of grassland conditions. The results indicate that this method is capable of accurately estimating grazing intensity, with a R^2 of 0. 7996 w h en v al id ated by measurements on the ground. Grazing intensity in the Xeltala pastures ranged from 1 to 2. 5 Au/ha, with the latter being over-grazed. The local map suggested that heavy grazing areas were distributed around a small lake and in certain locations where abundant grass favoured concentrations of cattle. Light grazing areas, on the other hand, were located in enclosed places where the grass was reserved for winter supplies. Extending the study area to include the city of Hailaer, the grazing intensity map clearly demonstrated the variations between areas of light, moderate and over-grazing, with Hailaer in the southwest appearing as extremely lightly grazed compared to the northeastern meadows.