Mapping Riparian Vegetation Functions Using 3D Bispectral LiDAR Data

Marianne Laslier,Simon Dufour,Laurence Hubert-Moy

doi:10.3390/w11030483

Marianne Laslier, Simon Dufour + Show 1 more

Open Access

https://doi.org/10.3390/w11030483

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Abstract

Riparian zones experience many anthropic pressures and are the subject of European legislation to encourage their monitoring and management, to attenuate these pressures. Assessing the effectiveness of management practices requires producing indicators of ecological functions. Laser Detection and Ranging (LiDAR) data can provide valuable information to assess the ecological status of riparian zones. The objective of this study was to evaluate the potential of LiDAR point clouds to produce indicators of riparian zone status. We used 3D bispectral LiDAR data to produce several indicators of a riparian zone of a dammed river in Normandy (France). The indicators were produced either directly from the 3D point clouds (e.g., biomass overhanging the channel, variation in canopy height) or indirectly, by applying the Random Forest classification algorithm to the point clouds. Results highlight the potential of 3D LiDAR point clouds to produce indicators with sufficient accuracy (ca. 80% for the number of trunks and 68% for species composition). Our results also reveal advantages of using metrics related to the internal structure of trees, such as penetration indexes. However, intensity metrics calculated using bispectral properties of LiDAR did not improve the quality of classifications. Longitudinal analysis of the indicators revealed a difference in attributes between the reservoir and areas downstream from it.

Highlights

Riparian zones provide multiple ecosystem services, such as sediment bank stabilization, water flux regulation, flood prevention, and habitat provision [1]
Preprocessing and Validation of Elevation Extracted from the Bare Soil LiDAR Point Cloud
All 32 metrics were kept in the Random Forest model for the classification (Figure 5)

Summary

Introduction

Riparian zones provide multiple ecosystem services, such as sediment bank stabilization, water flux regulation, flood prevention, and habitat provision [1]. The riparian zone describes the area that interacts with the river, i.e., that can be flooded by the river and can provide materials to the river. Since riparian zones intersect land and water, they are exceptionally rich in biodiversity [2]. They function as ecological corridors and provide a high diversity of habitats for birds and other animal species [3]. Riparian zones are subject to many anthropic pressures, such as land cover modification (urbanization, deforestation, etc.) and flow regulation. River ecosystems are the focus of management and restoration projects [5]

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