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草业学报 ›› 2023, Vol. 32 ›› Issue (4): 15-29.DOI: 10.11686/cyxb2022147

• 研究论文 • 上一篇    下一篇

基于Sentinel-2数据的青海门源县天然草地生物量遥感反演研究

郭芮1(), 伏帅1, 侯蒙京1, 刘洁1, 苗春丽1, 孟新月1, 冯琦胜1, 贺金生1,2, 钱大文3, 梁天刚1()   

  1. 1.兰州大学草地农业科技学院,草地农业生态系统国家重点实验室,兰州大学农业农村部牧草创新重点实验室,兰州大学草地农业教育工程研究中心,甘肃 兰州 730020
    2.北京大学城市与环境学院,北京 100871
    3.中国科学院西北高原生物研究所,青海 西宁 810008
  • 收稿日期:2022-03-31 修回日期:2022-04-28 出版日期:2023-04-20 发布日期:2023-01-29
  • 通讯作者: 梁天刚
  • 作者简介:E-mail: tgliang@lzu.edu.cn
    郭芮(1999-),女,甘肃平凉人,在读硕士。E-mail: guor2018@lzu.edu.cn
  • 基金资助:
    国家重点研发计划(2019YFC0507701);国家自然科学基金(31672484);中国工程院咨询研究项目(2022-HZ-5);财政部和农业农村部:国家现代农业产业技术体系和兰州大学中央高校基本科研业务费专项资金(lzujbky-2021-kb13)

Remote sensing retrieval of nature grassland biomass in Menyuan County, Qinghai Province experimental area based on Sentinel-2 data

Rui GUO1(), Shuai FU1, Meng-jing HOU1, Jie LIU1, Chun-li MIAO1, Xin-yue MENG1, Qi-sheng FENG1, Jin-sheng HE1,2, Da-wen QIAN3, Tian-gang LIANG1()   

  1. 1.College of Pastoral Agriculture Science and Technology,Lanzhou University,State Key Laboratory of Grassland Agro-ecosystem,Key Laboratory of Grassland Livestock Industry Innovation,Ministry of Agriculture and Rural Affairs,Engineering Research Center of Grassland Industry,Ministry of Education,Lanzhou 730020,China
    2.College of Urban and Environmental Science,Peking University,Beijing 100871,China
    3.Northwest Institute of Plateau Biology,Chinese Academy of Science,Xining 810008,China
  • Received:2022-03-31 Revised:2022-04-28 Online:2023-04-20 Published:2023-01-29
  • Contact: Tian-gang LIANG

摘要:

草地地上物生物量(AGB)是评价草地生产力的重要指标,精准反演天然草地的AGB,对草地长势监测和草畜平衡评估具有重要的意义。由于常用的遥感数据(如Landsat和MODIS等)受较低时间或空间分辨率引发的诸多问题的影响,因此探索具有更高时空分辨率及更多光谱波段的Sentinel-2卫星数据在县域尺度的草地植被监测状况具有极其重要的作用。利用Sentinel-2卫星遥感影像和青海门源县实测草地AGB数据,构建了基于随机森林(RF)、支持向量机(SVM)和人工神经网络(ANN)3种机器学习方法的草地生物量估算模型,研究了2019-2021年门源县天然草地生物量时空分布特征。结果表明:1) Sentinel-2卫星影像的3个原始波段(B2、B6、B11)和2种植被指数[反红边叶绿素指数(IRECI)和特定色素简单比值植被指数(PSSRa)],是草地AGB敏感的特征变量。其中,红边波段(B5、B6、B7)对天然草地AGB遥感反演具有重要作用。2)基于RF算法的草地AGB估测模型是门源县天然草地生物量估测的最优模型(验证集R2 为0.72,RMSE为622.616 kg·hm-2),优于SVM模型(验证集R2 为0.66,RMSE为698.271 kg·hm-2)和ANN模型(验证集R2 为0.63,RMSE为730.676 kg·hm-2)。3)2019-2021年门源县天然草地AGB平均值为3360.26~3544.00 kg·hm-2。总体来说, 2019-2021年门源县草地AGB呈先上升后下降的趋势,具有从四周向中部逐渐减少的空间分布特点。

关键词: Sentinel-2, 地上生物量, 机器学习, 天然草地, 反演模型

Abstract:

Above-ground biomass (AGB) is an important indicator for evaluating grassland productivity. Accurate inversion of AGB of natural grassland is of great significance for monitoring grassland growth and evaluating the feed balance of forage-livestock. As commonly used remote sensing data (such as Landsat and MODIS) suffer from by many problems caused by low temporal and spatial resolution, it is extremely important to explore Sentinel-2 satellite data with higher temporal and spatial resolution and more spectral bands in monitoring grassland vegetation at county scale. In this study, we used Sentinel-2 satellite remote sensing imagery and the AGB data of Menyuan County, Qinghai Province to construct a grassland biological monitoring system based on random forest (RF), support vector machine (SVM) and artificial neural network (ANN) methods, to study the spatial and temporal distribution characteristics of natural grassland biomass in Menyuan County from 2019 to 2021. It was found that: 1) The three original bands(B2,B6,B11)and two vegetation indices, inverted red edge chlorophyll index(IRECI),and pigment specific simple ratio chlorophyll index(PSSRa),were the important variables for AGB quantification in natural grassland. Among these,red-edge bands(B5,B6,B7)play an important role in remote sensing inversion of natural grassland AGB. 2) The AGB estimation model based on the RF algorithm was the optimal model(validation set R2 0.72, RMSE 622.616 kg·ha-1)for natural grassland biomass estimation in Menyuan County, which was superior to the SVM model(validation set R2 0.66,RMSE 698.271 kg·ha-1)and the ANN model(validation set R2 0.63,RMSE 730.676 kg·ha-1). 3) The average value of AGB of natural grassland in Menyuan County from 2019 to 2021 ranged from 3360.26-3544.00 kg·ha-1. In general, the AGB of grassland in Menyuan County from 2019 to 2021 showed a trend of initially increasing and then decreasing, with a spatial distribution pattern of gradual decrease from the periphery to the middle.

Key words: Sentinel-2, aboveground biomass, machine learning, nature grassland, inversion mode