Change detection and landscape structure mapping using remote sensing

Abstract

Satellite remote sensing has long held promise as a powerful method of detecting forest canopy changes and mapping landscape structure over vast, often multi-jurisdictional forest areas. Landsat Thematic Mapper (TM) spectral response, for example, can be related accurately to changes in physiology and cover at a range of small to intermediate mapping scales. These data have been available continuously for almost 20 years; many areas have earlier satellite image archives stretching back to the 1970s. When considering spatially-explicit changes to landscapes-caused by natural and human disturbances-over this time period, digital, synoptic, and repeatable satellite remotely-sensed data are emerging as the observational media of choice that forest managers must possess and use wisely. In this paper, successful use of satellite remote sensing in two of Canada's Model Forests is described. First, in the Fundy Model Forest in southeastern New Brunswick, a 15-year TM image sequence was used to detect area changes associated with different harvesting and silvicultural practices. Second, in the Foothills Model Forest in west-central Alberta, grizzly bear habitat maps have been created from multi-scene TM land cover mosaics. These map products constitute critical information on landscape change and configuration required to answer key management questions. The paper concludes with a prognosis for the future role of satellite remote sensing in sustainable forest management as data quality continues to improve (i.e., increasing spatial, spectral, temporal, and radiometric resolutions), and methods are brought into the purview of forest managers and practitioners.Key words: remote sensing, landscape change, forest fragmentation, human disturbance, management information needs, habitat La télédétection a longtemps promis de se transformer en un outil puissant de détection des modifications du couvert forestier et de cartographie des structures du paysage sur de vastes territoires forestiers relevant souvent de plusieurs juridictions. La réponse spectrale du Landsat Thematic Mapper (TM), par exemple, peut être rattachée avec précision aux changements dans la physiologie et le couvert selon des échelles de cartographie de petites à intermédiaires. Ces données sont disponibles de façon continue depuis près de 20 ans; des archives d'images satellites existent pour certaines superficies depuis le début des années '70. Lorsqu'on examine les modifications au paysage qui peuvent être perçues de l'espace, à la suite de perturbations humaines ou naturelles, au cours de cette péri-ode, les données de télédétection numériques, synoptiques et répétitives s'avèrent être le média d'observation de choix que les amé-nagistes forestiers doivent détenir et utiliser à bon escient. Cet article décrit l'utilisation réussie de la télédétection spatiale pour deux forêts modèles du Canada. Premièrement, dans la Forêt modèle de Fundy du sud-est du Nouveau-Brunswick, une séquence d'images du TM au cours de 15 ans a été utilisée pour détecter les modific...

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