title: Unmanned aerial survey of fallen trees in a deciduous broadleaved forest in eastern 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.
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Nagai
authors.affiliation: Department of Forest Entomology, Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Ibaraki, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
authors.forename: Hadi
authors.initials: H
authors.lastname: Fadaei
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
authors.forename: Reiichiro
authors.initials: R
authors.lastname: Ishii
authors.affiliation: Department of Forest Entomology, Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Ibaraki, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Okabe
authors.affiliation: Department of Forest Entomology, Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Ibaraki, Japan.
authors.forename: Hisatomo
authors.initials: H
authors.lastname: Taki
authors.affiliation: Center of Environmental Remote Sensing, Chiba University, Chiba, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Honda
authors.affiliation: Center of Environmental Remote Sensing, Chiba University, Chiba, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kajiwara
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokohama, Japan.
authors.forename: Rikie
authors.initials: R
authors.lastname: Suzuki
mesh_terms: D000401:Aircraft; D044822:Biodiversity; D003625:Data Collection / Q000379:methods*; D017753:Ecosystem; D004784:Environmental Monitoring; D065928:Forests; D018515:Plant Leaves; D058998:Remote Sensing Technology; D014197:Trees