摘要
草地非生长季植被是牲畜在冬春季节的主要饲料来源,研究非生长季植被对估算当地牧场载畜量有重要意义。本文以甘南州为研究区,通过小型无人机搭载相机获得60 m×60 m的草地非生长季植被数码照片,通过监督分类得到样地非生长季植被覆盖度数据。利用MODIS/Terra+Aqua双向反射分布函数和半球反射率产品MCD43A4,以及Landsat8 OLI影像数据,分别计算土壤耕作指数(soil tillage index,STI)、干枯燃料指数(dead fuel index,DFI)、归一化差异耕作指数(normalized difference tillage index,NDTI)等9种植被指数,通过分析不同植被指数与非生长季植被覆盖度之间的相关性,建立草地非生长季植被覆盖度回归模型,通过评价模型的精度来对比不同数据源估算草地非生长季植被覆盖度的能力,并筛选出甘南州草地非生长季植被覆盖度的最优反演模型,分析其空间分布特征。结果表明:1)Landsat8 OLI数据比MODIS数据更适合于甘南地区的草地非生长季植被覆盖度的反演;2)草地非生长季植被覆盖度估测的最优指数是NDTI,其线性模型为y=1432.074x–166.855(R2=0.407),是草地非生长季植被覆盖度最优反演模型;3)甘南州2018年4月–5月草地植被覆盖度总体西部高、东部低,大部分地区覆盖度介于20%~50%,仅有夏河北部、合作中部以及玛曲东南部少部分区域覆盖度小于20%,玛曲西北部覆盖度大于60%。本研究结果可为甘南州季节载畜量计算提供依据。
Vegetation from non-growing seasons is a vital animal feed type for livestock in winter and spring.Therefore,estimates of the livestock carrying capacity of local ranches are important for studying non-growing season vegetation.In this paper,Gannan prefecture was taken as the research area,and 60 m×60 m digital photos of non-growing season vegetation of the prefecture’s grasslands were obtained via cameras mounted on small unmanned aerial vehicles(UVAs).The non-growing season vegetation coverage was obtained by a supervision classification from digital photos.Using the MODIS/Terra+Aqua bidirectional reflection distribution function and the hemispheric reflectivity product of MCD43 A4 together with the Landsat8 OLI image data,the soil tillage index(STI),dead fuel index(DFI),and normalized difference tillage index(NDTI)a total of 9 vegetation indexes were calculated.By analyzing the correlations between different vegetation indexes and fractional vegetation cover(FVC),a regression model of grassland FVC in the non-growing season was established;then,the accuracy of model was evaluated to compare the ability of different data sources that can most accurately estimate the FVC.The results show that:1)Landsat8 OLI data is more suitable than MODIS data for studying FVC during the non-growing season in the Gannan grasslands;2)NDTI is the best index for non-growing season FVC estimations in the study area,and its linear estimation model of y=1432.074 x–166.855(R2=0.407)is the optimal inversion model of FVC in the nongrowing season;3)From April to May in 2018,Gannan has a high FVC in the west and a low FVC in the east;coverage rates in most regions ranges from 20%to 50%,with only the rates in the north part of Xiahe,the central part of Hezuo and the southeast part of Maqu being less than 20%.The coverage rate in the northeast part of Maqu is over 60%.This study can provide a basis for calculating the seasonal livestock carrying capacity in Gannan prefecture.
作者
冷若琳
张瑶瑶
谢建全
李芙凝
胥刚
崔霞
LENG Ruolin;ZHANG Yaoyao;XIE Jianquan;LI Funing;XU Gang;CUI Xia(Key Laboratory of Western China’s Environmental Systems(Ministry of Education),College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,Gansu,China;State Key Laboratory of Grassland Agro-ecosystems/College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,Gansu,China)
出处
《草业科学》
CAS
CSCD
2019年第11期2742-2751,共10页
Pratacultural Science
基金
国家重点研发计划(2018YFC0406602)
兰州大学中央高校基本科研业务费专项基金(lzujbky-2018-k15)