Abstract
Habitat studies are essential in order to understand the dynamics of migratory caribou herds and to better define management strategies. In this paper, multi-date Landsat images are used to map lichen in the summer range of the George River Caribou Herd (GRCH), Québec-Labrador (Canada), over the period from 1976 to 1998. Multi-Spectral Scanner scenes from the seventies and Thematic Mapper scenes from the eighties and nineties were radiometrically normalized and processed using spectral mixture analysis to produce lichen fraction maps and lichen change maps. Field sites, surveyed during summer campaigns in 2000 and 2001, are used to validate the lichen maps. Results show a good agreement between field data and the lichen results obtained from image analysis. Maps are then interpreted in the context of previous caribou dynamics and habitat studies conducted in the study area over the last three decades. The remote-sensing results confirm the habitat degradation and herd distribution patterns described by other investigators. The period between 1976-1979 and 1985-1986 is characterized by a localized decrease in lichen cover in the southern part of the study area, whereas from 1985-1986 to 1998 the decrease in lichen cover extends northward and westward. This period coincides with the widest extent of the GRCH summer range and activity. The approach presented in this paper provides a valuable means for better understanding the spatio-temporal relation between herd dynamics and distribution, as well as habitat use. Satellite remote sensing imagery is a useful data source, providing timely information over vast and remote territories where caribou populations cannot be surveyed and managed on a frequent basis.
Highlights
Migratory caribou (Rangifer tarandus) herds are vastly distributed across circumpolar regions and can total a few hundred thousands of heads (Banfield, 1961; Williams & Heard, 1986)
Lichen sites were well discriminated from non lichen sites and the relative variations of lichen cover in the field were well conserved by the procedure, based on the validation data
The area covered by the historical time series of Landsat images corresponds to the summer range of the George River Caribou Herd (GRCH), and more precisely to the calving grounds mapped in the late 1980s (Fig. 2)
Summary
Migratory caribou (Rangifer tarandus) herds are vastly distributed across circumpolar regions and can total a few hundred thousands of heads (Banfield, 1961; Williams & Heard, 1986). The herds represent a vital food and cultural resource for native communities, and are an important economic resource. In northern Québec, for example, around 15 000 caribou hunting licenses were sold in 2001 (FAPAQ, 2003). Climate, human activities, and food availability are known to influence caribou population dynamics (Bergerud, 1980; Skogland, 1986; Messier et al, 1988; Wolfe et al, 2000; Dyer et al, 2002), but the impact of each of these factors is not well understood. Monitoring populations and habitats is essential to ascertain the sustainable management of caribou herds
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