한빛사논문
- 조회693
Soyeon Baea,*, Jörg Müllera,b, Bernhard Försterc, Torben Hilmersd, Sophia Hochreina, Martin Jacobsd, Benjamin M. L. Leroye, Hans Pretzschd, Wolfgang W. Weissere, Oliver Mitessera
a) Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
b) Bavarian Forest National Park, 94481 Grafenau, Germany
c) Chair for Strategic Landscape Planning and Management, Technical University of Munich, 85354 Freising, Germany
d) Chair for Forest Growth and Yield Science, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
e) Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Technical University of Munich, 85354 Freising, Germany
*Correspondence: Soyeon Bae
Abstract
Quantifying tree defoliation by insects over large areas is a major challenge in forest management, but it is essential in ecosystem assessments of disturbance and resistance against herbivory. However, the trajectory from leaf-flush to insect defoliation to refoliation in broadleaf trees is highly variable. Its tracking requires high temporal- and spatial-resolution data, particularly in fragmented forests.
In a unique replicated field experiment manipulating gypsy moth Lymantria dispar densities in mixed-oak forests, we examined the utility of publicly accessible satellite-borne radar (Sentinel-1) to track the fine-scale temporal trajectory of defoliation. The ratio of backscatter intensity between two polarizations from radar data of the growing season constituted a canopy development index (CDI) and a normalized CDI (NCDI), which were validated by optical (Sentinel-2) and terrestrial laser scanning (TLS) data as well by intensive caterpillar sampling from canopy fogging.
The CDI and NCDI strongly correlated with optical and TLS data (Spearman’s ρ=0.79 and 0.84, respectively). The ΔNCDIDefoliation (A-C) significantly explained caterpillar abundance (R2=0.52). The NCDI at critical time-steps and ΔNCDI related to defoliation and refoliation well discriminated between heavily and lightly defoliated forests.
We demonstrate that the high spatial and temporal resolution and the cloud independence of Sentinel-1 radar potentially enable spatially unrestricted measurements of the highly dynamic canopy herbivory. This can help monitor insect pests, improve the prediction of outbreaks, and facilitate the monitoring of forest disturbance, one of the high priority Essential Biodiversity Variables, in the near future.
논문정보
- Research article
- 2021년 09월 (BRIC 등록일 2021-10-05)
- 국외 연구진
- 생명과학 > 분류/생태/환경생물학
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