title: Modeling Aboveground Biomass in Hulunber Grassland Ecosystem by Using Unmanned Aerial Vehicle Discrete Lidar.
abstract: Accurate canopy structure datasets, including canopy height and fractional cover, are required to monitor aboveground biomass as well as to provide validation data for satellite remote sensing products. In this study, the ability of an unmanned aerial vehicle (UAV) discrete light detection and ranging (lidar) was investigated for modeling both the canopy height and fractional cover in Hulunber grassland ecosystem. The extracted mean canopy height, maximum canopy height, and fractional cover were used to estimate the aboveground biomass. The influences of flight height on lidar estimates were also analyzed. The main findings are: (1) the lidar-derived mean canopy height is the most reasonable predictor of aboveground biomass (R² = 0.340, root-mean-square error (RMSE) = 81.89 g·m-2, and relative error of 14.1%). The improvement of multiple regressions to theR² and RMSE values is unobvious when adding fractional cover in the regression since the correlation between mean canopy height and fractional cover is high; (2) Flight height has a pronounced effect on the derived fractional cover and details of the lidar data, but the effect is insignificant on the derived canopy height when the flight height is within the range (<100 m). These findings are helpful for modeling stable regressions to estimate grassland biomass using lidar returns.
authors.affiliation: National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China. wangdongliang@caas.cn.|Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, Beijing 100101, China. wangdongliang@caas.cn.
authors.forename: Dongliang
authors.initials: D
authors.lastname: Wang
authors.affiliation: National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China. xinxiaoping@caas.cn.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Xin
authors.affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, Beijing 100101, China. shaoqq@igsnrr.ac.cn.
authors.forename: Quanqin
authors.initials: Q
authors.lastname: Shao
authors.affiliation: School of Environment and Technology, University of Brighton, Brighton BN2 4GJ, UK. M.Brolly@brighton.ac.uk.
authors.forename: Matthew
authors.initials: M
authors.lastname: Brolly
authors.affiliation: U.S. Geological Survey, Reston, VA 20192, USA. zzhu@usgs.gov.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China. chenjin@bnu.edu.cn.
authors.forename: Jin
authors.initials: J
authors.lastname: Chen
keywords: UAV lidar; aboveground biomass; canopy height; fractional cover; grasslands