Unmanned aerial survey of fallen trees in a deciduous broadleaved forest in eastern Japan

Tomoharu Inoue; Shin Nagai; Satoshi Yamashita; Hadi Fadaei; Reiichiro Ishii; Kimiko Okabe; Hisatomo Taki; Yoshiaki Honda; Koji Kajiwara; Rikie Suzuki

doi:10.1371/journal.pone.0109881

Unmanned aerial survey of fallen trees in a deciduous broadleaved forest in eastern Japan

PLoS One. 2014 Oct 3;9(10):e109881. doi: 10.1371/journal.pone.0109881. eCollection 2014.

Authors

Affiliations

¹ Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
² Department of Forest Entomology, Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Ibaraki, Japan.
³ Center of Environmental Remote Sensing, Chiba University, Chiba, Japan.

Abstract

Since fallen trees are a key factor in biodiversity and biogeochemical cycling, information about their spatial distribution is of use in determining species distribution and nutrient and carbon cycling in forest ecosystems. Ground-based surveys are both time consuming and labour intensive. Remote-sensing technology can reduce these costs. Here, we used high-spatial-resolution aerial photographs (0.5-1.0 cm per pixel) taken from an unmanned aerial vehicle (UAV) to survey fallen trees in a deciduous broadleaved forest in eastern Japan. In nine sub-plots we found a total of 44 fallen trees by ground survey. From the aerial photographs, we identified 80% to 90% of fallen trees that were >30 cm in diameter or >10 m in length, but missed many that were narrower or shorter. This failure may be due to the similarity of fallen trees to trunks and branches of standing trees or masking by standing trees. Views of the same point from different angles may improve the detection rate because they would provide more opportunity to detect fallen trees hidden by standing trees. Our results suggest that UAV surveys will make it possible to monitor the spatial and temporal variations in forest structure and function at lower cost.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aircraft*
Biodiversity
Data Collection / methods*
Ecosystem
Environmental Monitoring*
Forests*
Plant Leaves
Remote Sensing Technology*
Trees*

Grants and funding

This study was funded by the Environment Research and Technology Development Fund (S-9) of the Ministry of the Environment of Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.