Mangrove growth analysis with multi-temporal UAV LiDAR

Keywords: UAV, LiDAR, multi-temporal analysis, mangrove
Abstract Type: Virtual Paper Abstract

Abstract

Quantifying the mangrove height growth rate is important for the understanding of mangrove growth as well as its coupling with the other ecosystems and the climate. However, research on this topic has been lacking due to the shortage of multi-temporal mangrove tree height (TH) data and tree-level analysis methods. In this study, we explore the possibility of employing multi-year UAV-LiDAR data for mangrove tree height growth characterization. Regarding data, we compared the UAV-LiDAR data with field-measured THs and found that they are comparable with -15~+10 cm deviation. The deviation between the two datasets collected using the same LiDAR sensor, though, is only 2 cm, indicating the validity of adopting multi-year UAV-LiDAR data for mangrove TH growth analysis. Regarding methods, we tested a tree-based approach and a grid-based approach. The results showed that the mangrove TH growth rate estimated using the tree-based approach agreed better with the field measurements. In addition, the variation of TH growth rate among different mangrove species, clumpiness, and invasion status were successfully depicted using UAV-LiDAR. Although still in the developing stage, this paper presents the first work for mangrove TH growth quantification using multi-temporal UAV-LiDAR data. The capacity of this quickly emerging remote sensing technique in individual mangrove change analysis is revealed. We proposed a recommended diagram for UAV-LiDAR-based tree height growth rate measurement. The limitations and uncertainties embedded in the data source, methodology, and results interpretation were also discussed.