Skip to Main Content
Using satellite imagery to evaluate bark beetle-caused tree mortality reported in aerial surveys in a mixed conifer forest in northern Idaho, USAAuthor(s): Benjamin C. Bright; Andrew T. Hudak; Joel M. Egan; Carl L. Jorgensen; Franciel E. Rex; Jeffrey A. Hicke; Arjan J. H. Meddens
Source: Forests. 11: 529.
Publication Series: Scientific Journal (JRNL)
Station: Rocky Mountain Research Station
Download Publication (2.0 MB)
DescriptionBark beetles cause significant tree mortality in western North America. The United States Forest Service coordinates annual insect and disease surveys (IDS) by observers in airplanes to map and quantify the tree mortality caused by beetles. The subjective nature of these surveys means that accuracy evaluation is important for characterizing uncertainty. Furthermore, the metric reported for quantifying tree mortality recently changed (2012-2018 depending in region) from killed trees per acre to percent tree mortality within damage polygons, posing challenges for linking older and newer records. Here we evaluated IDS severity estimates in a beetle-affected forest in northern Idaho, USA using fine-resolution satellite imagery, which permitted greater areal coverage than field data. We first used well-established methods to map beetle-caused tree mortality in two WorldView-2 (WV2) images with a high accuracy relative to field observations. Trees-per-acre measurements within collocated IDS polygons were then converted to percent mortality using three methods and evaluated with the WV2 maps. The overall accuracies for the three methods ranged from 35-38% (for methods that used five percent-mortality classes) and 49-56% (three classes). When IDS and WV2 estimates of mortality severity that were within +/-15% of each other were considered accurate, overall accuracies were 71-78%. Within the aerial survey damage polygons, the total mortality area tended to be overestimated relative to WV2. WV2 imagery identified ~50% more mortality across the study region compared with the IDS methods, with most of the difference occurring where damage was low severity or in wilderness areas. Severity of Douglas-fir beetle-caused tree mortality was estimated the most accurately, whereas severity of mountain pine beetle-caused tree mortality was estimated the least accurately. Future studies that control for temporal ambiguity between IDS and satellite imagery, as well as IDS spatial error, might provide better assessments of IDS severity accuracy. Our study increases the usefulness of the rich aerial survey database by providing estimates of uncertainty in the IDS database of tree mortality severity.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationBright, Benjamin C.; Hudak, Andrew T.; Egan, Joel M.; Jorgensen, Carl L.; Rex, Franciel E.; Hicke, Jeffrey A.; Meddens, Arjan J. H. 2020. Using satellite imagery to evaluate bark beetle-caused tree mortality reported in aerial surveys in a mixed conifer forest in northern Idaho, USA. Forests. 11: 529.
Keywordsbark beetles, tree mortality, mixed conifer forests, aerial surveys, satellite imagery
- Evaluating methods to detect bark beetle-caused tree mortality using single-date and multi-date Landsat imagery
- Use of MODIS NDVI products to map tree mortality levels in forests affected by mountain pine beetle outbreaks
- West Coast forest insects
XML: View XML