Classification of linear environmental impacts and habitat fragmentation by object oriented analysis of aerial photograp
The increase of tourism in coastal protected areas is a potential driver for ecosystem fragmentation, as it frequently involves damages to their biodiversity values. One of the key issues in the management of protected areas is their access regulation in
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R.A.D. Varela,1 P.R. Rego, 1 M.S.C. Iglesias2 1
Botanic & Biogeography Laboratory. Department of Botany. I.B.A.D.E.R. University of Santiago de Compostela. Escola Politécnica Superior, Campus Universitario s/n, E27002 Lugo, Spain. E-mail: [email protected], [email protected]
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Department of Agroforestry Engineering, University of Santiago de Compostela. Escola Politécnica Superior, Campus Universitario s/n, 27002 Lugo, Spain E mail: [email protected]
KEYWORDS: Vegetation monitoring, orthoimage classification, fuzzy logic, object oriented analysis, context, linear features ABSTRACT: The increase of tourism in coastal protected areas is a potential driver for ecosystem fragmentation, as it frequently involves damages to their biodiversity values. One of the key issues in the management of protected areas is their access regulation in order to avoid negative effects of trampling on natural and semi-natural habitats. Protection measures need to be carefully designed to achieve an effective protection of biodiversity while minimizing as possible the constraints to tourism development. The accurate design and monitoring of performance of such measures needs effective methods to evaluate fragmentation. In this work, we aimed at the development of a consistent method for the automatic recognition of linear environmental impacts (paths and tracks) on natural and semi-natural habitats using colour aerial photo-
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R.A.D. Varela, P.R. Rego, M.S.C. Iglesias
graphs. The method is based on a multi-scale segmentation of the images. Brightness, shape and connectivity criteria were implemented at several scales of analysis by means of a fuzzy knowledge base, allowing the recognition of linear elements corresponding to networks of trails. We used as study case a protected area in the NW coast of the Iberian Peninsula with a complex vegetation pattern. The method allowed the general discrimination of linear artificial features, causing environmental impacts and human-driven habitat fragmentation, against other linear elements with similar brightness and shape, but different thematic meaning regarding their conservation implications.
1 Introduction Environmental planning in coastal protected areas needs taking into account the pressure on biodiversity due to the increase of leisure and tourism activities in these locations. In fact, tourism pressure may cause important damages to biodiversity values in ecosystems with high vulnerability and low resilience. For instance, the effects of trampling on habitats like coastal sand dunes may remove and destabilize the vegetation cover and cause its fragmentation, particularly when creating linear features like footpaths. Although several definitions may be found in the literature, habitat fragmentation is often regarded as a process in which “a large expanse of habitat is transformed into a number of smallest patches of smaller total area, isolated from each other by a matrix of habitats unlike the original” (Wilcove et al. 1986). Linear infrastructures are acknowledged to be one o
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