Aboveground Biomass Estimation Using Structure from Motion Approach with Aerial Photographs in a Seasonal Tropical Forest

Tetsuji Ota,Nobuya Mizoue,Heng Sokh,Gen Takao,Eriko Ito,Nang Ket,Shigejiro Yoshida,Yukako Monda,Tsuyoshi Kajisa,Yasumasa Hirata,Jumpei Toriyama,Vuthy Ma,Katsuto Shimizu,Sophal Chann,Hideki Saito,Miyuki Ogawa,Takio Sano,Naoyuki Furuya,Yoshiyuki Kiyono

doi:10.3390/f6113882

Abstract

We investigated the capabilities of a canopy height model (CHM) derived from aerial photographs using the Structure from Motion (SfM) approach to estimate aboveground biomass (AGB) in a tropical forest. Aerial photographs and airborne Light Detection and Ranging (LiDAR) data were simultaneously acquired under leaf-on canopy conditions. A 3D point cloud was generated from aerial photographs using the SfM approach and converted to a digital surface model (DSMP). We also created a DSM from airborne LiDAR data (DSML). From each of DSMP and DSML, we constructed digital terrain models (DTM), which are DTMP and DTML, respectively. We created four CHMs, which were calculated from (1) DSMP and DTMP (CHMPP); (2) DSMP and DTML (CHMPL); (3) DSML and DTMP (CHMLP); and (4) DSML and DTML (CHMLL). Then, we estimated AGB using these CHMs. The model using CHMLL yielded the highest accuracy in four CHMs (R2 = 0.94) and was comparable to the model using CHMPL (R2 = 0.93). The model using CHMPP yielded the lowest accuracy (R2 = 0.79). In conclusion, AGB can be estimated from CHM derived from aerial photographs using the SfM approach in the tropics. However, to accurately estimate AGB, we need a more accurate DTM than the DTM derived from aerial photographs using the SfM approach.

Highlights

Tropical forests have been recognized as an important type of ecosystem that can be used in mitigating climate change, because they sequester and store more carbon than any other vegetation types [1,2]
Our study has confirmed that mean height is a well suited index to estimate aboveground biomass (AGB), even if we used a DSM derived from aerial photography using the Structure from Motion (SfM) approach
These results imply that AGB estimation using metrics from a combination of aerial photography with the SfM approach and airborne Light Detection and Ranging (LiDAR) was comparable to that using metrics from only airborne LiDAR

Summary

Introduction

Tropical forests have been recognized as an important type of ecosystem that can be used in mitigating climate change, because they sequester and store more carbon than any other vegetation types [1,2]. Tropical forests are being deforested and degraded dramatically through agricultural expansion, wood extraction, infrastructure development, and other natural and anthropogenic processes [3,4]. Reducing emissions from deforestation and forest degradation, and the role of conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries (REDD+) is one mitigation mechanism related to deforestation and forest degradation in tropical forests. Remote sensing with ground-based inventories is expected to play an important role as the method that can be used to quantify AGB for the implementation of REDD+ For the implementation of REDD+, a scientifically robust method is required to quantify aboveground biomass (AGB) [9].

Methods

Results

Conclusion