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Selected Publication:

Immitzer, M; Atzberger, C.
(2014): Early Detection of Bark Beetle Infestation in Norway Spruce (Picea abies, L.) using WorldView-2 Data
PHOTOGRAMM FERNERKUN. 2014; (5): 351-367. FullText FullText_BOKU

Abstract:
In Central Europe and North America, bark beetle infestations cause considerable economic losses. If infested trees are not rapidly removed, large areas can be damaged. Removal of infested trees has to be done during the so-called "green-attack" stage, which is before the bark beetles move to other trees. Field surveys even if they are feasible are cost intensive and impractical if large areas have to be monitored. The aim of the study was to analyse the suitability of 8-band WorldView-2 satellite imagery for detecting bark beetle infestations of two intensity stages (e.g. "dead" and "green-attack") against "healthy" (non-attacked) trees. For classifying individual trees two classifiers, random forest and logistic regression, were evaluated. Despite the relative large class overlap in the spectral signatures, the sample trees (n = 600) could be assigned to the classes "dead", "green-attack", and "healthy" with an overall accuracy of about 75%. Producerxxxs and userxxxs accuracies of all classes were around 70%. The best result was obtained with random forests using the eight spectral bands of a WorldView-2 image acquired in July. With this dataset, an overall accuracy of 76% and a kappa coefficient of 0.61 were achieved. For the separation of the classes "healthy" and "green-attack", vegetation indices based on 2-band normalized differences as well as ratios yielded nearly as good results as the classification with all eight spectral bands. The best results were obtained by combining either the Green or Yellow band with the Near Infrared 1. With regard to individual bands, the Yellow and the Red band are defined as most important ones. We can conclude that 8-band WorldView-2 imagery has the potential for creating hotspot maps of infested trees or of trees with an increased risk of infestation. This could have positive implications for the forest practice.
Authors BOKU Wien:
Atzberger Clement
Immitzer Markus
BOKU Gendermonitor:


Find related publications in this database (Keywords)
WorldView-2
bark beetle infestation
tree vitality
green-attack
pre-visual detection
Norway spruce


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