UAV-based individual shrub aboveground biomass estimation calibrated against terrestrial LiDAR in a shrub-encroached grassland

doi:10.1016/j.jag.2021.102358

	UAV-based individual shrub aboveground biomass estimation calibrated against terrestrial LiDAR in a shrub-encroached grassland
	Zhao, Yujin ; Liu, Xiaoliang 3; Wang, Yang ; Zheng, Zhaoju 2; Zheng, Shuxia ; Zhao, Dan 1; Bai, Yongfei
	2021
发表期刊	INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION
ISSN	1569-8432
卷号	101
摘要	Shrub encroachment is an important ecological issue that is increasingly receiving global attention in arid and semiarid grasslands. Monitoring the spatial distribution of encroached shrub aboveground biomass (AGB) is critical for ecological conservation and adaptive ecosystem management. However, the low stature and fine spatial heterogeneity of encroached shrub communities increase difficulties for coarse spatial-resolution satellite images to adequately capture detailed characteristics of individual shrubs. Unmanned aerial vehicle (UAV) can acquire centimeter-level optical images or high-density LiDAR point cloud data, providing an effective means to map encroached shrub AGB spatially explicitly, even at the individual scale. In this study, we first extracted the individual shrubs based on thresholds in normalized difference vegetation index (NDVI) and canopy height model (CHM) using UAV-based multispectral and LiDAR data. For each shrub, we then derived and determined the dominant geometric, spectral, and textural features from the high-resolution multispectral image and the volumetric features from the LiDAR data as predictors of shrub AGB. Finally, we compared the capability of different data sources (UAV-based multispectral image, LiDAR, and their combination) and regression methods (multiple linear, random forest, and support vector regression) to estimate and map the individual shrub AGB in the study area. The volume-based approaches to individual shrub AGB, including global convex hull method, voxel method, and surface differencing method, were also employed using terrestrial laser scanning (TLS) to further calibrate the UAV-based estimation. Our results show that individual shrubs can be accurately extracted based on the threshold method with an overall classification accuracy of 91.8%. The UAV-based AGB estimation suggests that the textural feature, the sum of contrast metric within the individual shrub canopy, is the most important predictor of individual shrub AGB, followed by volumetric, geometric and spectral features. Moreover, the high-resolution multispectral image shows greater potential (R2 = 0.83, RMSE = 106.46 g) than LiDAR (R2 = 0.77, RMSE = 123.33 g) in the estimation of individual shrub AGB, and their combination can only slightly improve the estimation accuracy (R2 = 0.86, RMSE = 101.97 g). Our results also show that TLS-derived volume based on the surface differencing method obtained the best prediction accuracy of individual shrub AGB (R2 = 0.91, RMSE = 79.98 g), and can be used as an alternative of destructive harvesting. This study provides a new insight for quantifying and mapping individual shrub AGB using UAV-based optical sensors and TLS without destructive harvesting in arid and semiarid grasslands.
关键词	Shrub encroachment Biomass Unmanned aerial vehicle (UAV) Terrestrial laser scanning Volume Individual shrub identification
学科领域	Remote Sensing
DOI	10.1016/j.jag.2021.102358
收录类别	SCI
语种	英语
WOS关键词	FROM-MOTION PHOTOGRAMMETRY ; AIRBORNE LIDAR ; CARAGANA-MICROPHYLLA ; TROPICAL FOREST ; VEGETATION ; CLASSIFICATION ; SURFACE ; HEIGHT ; IMAGES ; QUANTIFICATION
WOS研究方向	Science Citation Index Expanded (SCI-EXPANDED)
WOS记录号	WOS:000659161300002
出版者	ELSEVIER
文献子类	Article
出版地	AMSTERDAM
EISSN	1872-826X
资助机构	National Key R&D Program of China [2016YFC0500801, 2016YFC0500804] ; National Natural Science Foundation of China [41801230]
作者邮箱	yfbai@ibcas.ac.cn
作品OA属性	gold
引用统计	被引频次：23[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ibcas.ac.cn/handle/2S10CLM1/26628
专题	植被与环境变化国家重点实验室
作者单位	1.Chinese Acad Sci, Inst Bot, State Key Lab Vegetat & Environm Change, 20 Nanxincun, Beijing 100093, Peoples R China; Univ Chinese Acad Sci, Colleage Resources & Environm, Beijing 100049, Peoples R China 2.Chinese Acad Sci, Aerosp Informat Res Inst, State Key Lab Remote Sensing Sci, Beijing 100101, Peoples R China 3.Univ Zurich, Remote Sensing Labs, Dept Geog, CH-8057 Zurich, Switzerland 4.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst, Beijing 100101, Peoples R China
推荐引用方式 GB/T 7714	Zhao, Yujin,Liu, Xiaoliang,Wang, Yang,et al. UAV-based individual shrub aboveground biomass estimation calibrated against terrestrial LiDAR in a shrub-encroached grassland[J]. INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION,2021,101.
APA	Zhao, Yujin.,Liu, Xiaoliang.,Wang, Yang.,Zheng, Zhaoju.,Zheng, Shuxia.,...&Bai, Yongfei.(2021).UAV-based individual shrub aboveground biomass estimation calibrated against terrestrial LiDAR in a shrub-encroached grassland.INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION,101.
MLA	Zhao, Yujin,et al."UAV-based individual shrub aboveground biomass estimation calibrated against terrestrial LiDAR in a shrub-encroached grassland".INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION 101(2021).

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