Forest canopy height is one of the important forest parameters for accurately assessing forest biomass or carbon sequestration.ICESat-2 ATLAS provides the potential for retrieval of forest canopy height at global or regional scale,but the current canopy height product(ATL08)has coarse resolution and high uncertainty compared to airborne LiDAR-derived canopy height(hereafter ALCH)in mountainous regions,and is not ready for such ap-plications as biomass modeling at finer scale.The objective of this research was to explore the approach to accurately retrieve canopy height from ATLAS data by incorporating an airborne-derived digital terrain model(DTM)and a data-filtering strategy.By linking ATLAS ATL03 with ATL08 products,the geospatial locations,types,and(absolute)heights of photons were obtained,and canopy heights at different lengths(from 20 to 200 m at 20-m intervals)of segments along a track were computed with the aid of airborne LiDAR DTM.Based on the relationship between the numbers of canopy photons within the segments and accuracy of ATLAS mean canopy height compared to ALCH,a filtering method for excluding a certain portion of unreliable segments was proposed.This method was further applied to different ATLAS ground tracks for retrieval of canopy heights and the results were evaluated using corresponding ALCH.The results show that the incorporation of high-precision DTM and ATLAS products can considerably improve the retrieval accuracy of forest canopy height in mountainous regions.Using the proposed filtering approach,the correlation coefficients(r)between ATLAS canopy height and corre-sponding ALCH were 0.61-0.91,0.65-0.92,0.68-0.94 for segment lengths of 20,60,and 100 m,respectively;RMSE were 1.90-4.35,1.55-3.63,and 1.34-3.23 m for the same segment lengths.The results indicate the ne-cessity of using high-precision DTM and using the proposed filtering method to retrieve accurate canopy height from ICESat-2 ATLAS in mountainous regions with dense forest cover and complex terrain conditions.

Shiyun Pang;Guiying Li;Xiandie Jiang;Yaoliang Chen;Yagang Lu;Dengsheng Lu

State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province,Fujian Normal University,Fuzhou,350007,China;Institute of Geography,Fujian Normal University,Fuzhou,350007,China;Institute of East China Inventory and Planning,National Forestry and Grassland Administration,Hangzhou,310019,China

森林生态系统（英文版）

[1]Shiyun Pang;Guiying Li;Xiandie Jiang;Yaoliang Chen;Yagang Lu;Dengsheng Lu-.Retrieval of forest canopy height in a mountainous region with ICESat-2 ATLAS)[J].森林生态系统（英文版）,2022(04):491-502

ALCH,cessity

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