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ERE研究文章|利用G-LiHT激光雷达评估ICESat-2和GEDI轨道激光雷达在六个不同生物群落中的冠层高度测量

09 8月 2024 gabriels

The height of woody plants is a defining characteristic of forest and shrubland ecosystems because height responds to climate, soil and disturbance history. Orbiting LiDAR instruments, Ice, Cloud and land Elevation Satellite-2 (ICESat-2) and Global Ecosystem Dynamics Investigation LiDAR (GEDI), can provide near-global datasets of plant height at plot-level resolution. We evaluate canopy height measurements from ICESat-2 and GEDI with high resolution airborne LiDAR in six study sites in different biomes from dryland shrub to tall forests, with mean canopy height across sites of 0.5–40 m. ICESat-2 and GEDI provide reliable estimates for the relative height with RMSE and mean absolute error (MAE) of 7.49 and 4.64 m (all measurements ICESat-2) and 6.52 and 4.08 m (all measurements GEDI) for 98th percentile relative heights. Both datasets slightly overestimate the height of short shrubs (1–2 m at 5 m reference height), underestimate that of tall trees (by 6–7 m at 40 m reference height) and are highly biased (>3 m) for reference height <5 m, perhaps because of the difficulty of distinguishing canopy from ground signals. Both ICESat-2 and GEDI height estimates were only weakly sensitive to canopy cover and terrain slope (R2 < 0.06) and had lower error for night compared to day samples (ICESat-2 RMSE night: 5.57 m, day: 6.82 m; GEDI RMSE night: 5.94 m, day: 7.03 m). For GEDI, the day versus night differences varied with differences in mean sample heights for the day and night samples and had little effect on bias. Accuracy of ICESat-2 and GEDI canopy heights varies among biomes, and the highest MAE was observed in the tallest, densest forest (GEDI: 7.85 m; ICESat-2: 7.84 m (night) and 12.83 m (day)). Improvements in canopy height estimation would come from better discrimination of canopy photons from background noise for ICESat-2 and improvements in the algorithm for decomposing ground and canopy returns for GEDI. Both would benefit from methods to distinguish outlier samples.

文章介绍

Assessing canopy height measurements from ICESat-2 and GEDI orbiting LiDAR across six different biomes with G-LiHT LiDAR

Qiuyan Yu, Michael G Ryan, Wenjie Ji, Lara Prihodko, Julius Y Anchang, Njoki Kahiu, Abid Nazir, Jingyu Dai and Niall P Hanan

通讯作者：

Michael G Ryan，美国科罗拉多州立大学/美国农业部林务局洛基山研究站

期刊介绍

Environmental Research: Ecology

Environmental Research: Ecology（ERE）是一本多学科、金色开放获取的期刊，致力于以关于全球变化、弹性、减轻和适应影响的兼具科学进展和评估的方式，解决在环境科学、大尺度生态学、生物多样性和保护的交界领域的重要全球挑战。本刊为促进环境科学家、生态学家、资源管理者和政策制定者的对话提供了论坛。本刊鼓励所有的研究方法，包括定量、定性、实验、理论和应用方法。