TLSLEAF: Automatic Leaf Angle Estimates From Single-Scan Terrestrial Laser Scanning

• Published in: The New phytologist Vol. 232; no. 4; pp. 1876 - 1892
• Main Authors: Stovall, Atticus E. L., Masters, Benjamin, Fatoyinbo, Lola, Yang, Xi
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Wiley / New Phytologist Trust 01.11.2021; Wiley Subscription Services, Inc
• Subjects: Accessibility; Automation; Canopies; Canopy; Chlorophyll; Chlorophylls; Earth Resources And Remote Sensing; Ecological effects; Ecosystems; Estimates; Fluorescence; Foliage; forest; Interception; Laser applications; Lasers; Leaf angle; leaf angle distribution (LAD); Leaf area; Leaves; light detection and ranging (LiDAR); Light interception; Photosynthesis; Plant cover; radiative transfer model; Remote sensing; Scanning; Terrestrial environments; terrestrial laser scanning (TLS); trees; Terrestrial Laser Scanning (tls); Trees; 3d; Light Detection And Ranging (lidar); Radiative Transfer Model; Forest; Leaf Angle Distribution (lad)
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.17548

Leaf angle distribution (LAD) in forest canopies affects estimates of leaf area, light interception, and global-scale photosynthesis, but is often simplified to a single theoretical value. Here, we present TLSLeAF (Terrestrial Laser Scanning Leaf Angle Function), an automated open-source method of deriving LADs from terrestrial laser scanning. TLSLeAF produces canopy-scale leaf angle and LADs by relying on gridded laser scanning data. The approach increases processing speed, improves angle estimates, and requires minimal user input. Key features are automation, leaf–wood classification, beta parameter output, and implementation in R to increase accessibility for the ecology community. TLSLeAF precisely estimates leaf angle with minimal distance effects on angular estimates while rapidly producing LADs on a consumer-grade machine. We challenge the popular spherical LAD assumption, showing sensitivity to ecosystem type in plant area index and foliage profile estimates that translate to c. 25% and c. 11% increases in canopy net photosynthesis (c. 25%) and solar-induced chlorophyll fluorescence (c. 11%). TLSLeAF can now be applied to the vast catalog of laser scanning data already available from ecosystems around the globe. The ease of use will enable widespread adoption of the method outside of remote-sensing experts, allowing greater accessibility for addressing ecological hypotheses and large-scale ecosystem modeling efforts.