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A multi-resolution satellite imagery approach for large area mapping of ericaceous shrubs in Northern Québec, Canada

Summary

Published in International Journal of Applied Earth Observation and Geoinformation 11: 334-343

Invasive ericaceous shrubs (e.g. Kalmia angustifolia, Rhododendron groenlandicum, Vaccinium spp.) may reduce the regeneration and early growth of black spruce (Picea mariana) seedlings, the most economically important boreal tree species in Québec. Our study focused, therefore, on developing a method for mapping ericaceous shrubs from satellite images. The method integrates very high resolution satellite imagery (IKONOS) to guide classifiers applied to medium resolution satellite imagery (Landsat-TM). An object-oriented image classification approach was applied using Definiens eCognition software. An independent ground survey revealed 80% accuracy at the very high spatial resolution. We found that the partial use (70%) of classified polygons derived from the IKONOS images were an effective way to guide classification algorithms applied to the Landsat-TM imagery. The results of this latter classification (78.4% overall accuracy) were assessed by the remaining portion (30%) of unused very high resolution classified polygons. We further validated our method (65.5% overall accuracy) by assessing the correspondence of an ericaceous cover classification scheme done with a Landsat-TM image and results of our ground survey using an independent set of 275 sample plots. Discrimination of ericaceous shrub cover from other land cover types was achieved with precision at both spatial resolutions with producer accuracies of 87.7% and 79.4% from IKONOS and Landsat, respectively. The method is weaker for areas with sparse cover of ericaceous shrubs or dense tree cover. Our method is adapted, therefore, for mapping the spatial distribution of ericaceous shrubs and is compatible with existing forest stand maps.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

VAN LIER, Olivier R., Richard A. FOURNIER, Robert L. BRADLEY and Nelson THIFFAULT

Year of publication :

2009

Format :

PDF available upon request

Keywords :

résolution multiple, classification orientée objet, éricacée, kalmia à feuilles étroites, sylviculture des forêts naturelles résineuses, kalmia angustifolia, Sylviculture et rendement des forêts naturelles - peuplements résineux, silviculture and yield of natural forests - softwood stands, sheep laurel, multi-resolution, object-oriented classification, ericaceous shrubs

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