In northeastern Alberta, Canada, continued expansion of the oil and gas industry along with timber harvesting has raised concerns that the resulting environmental changes may negatively affect the woodland caribou (Rangifer tarandus caribou) population in this region. Caribou are a threatened species in Alberta, and populations in northeastern Alberta appear to be stable or slightly decreasing. The spatial distribution of caribou in relation to alternative prey (commonly moose [Alces alces]) has been hypothesized to affect the level of wolf (Canis lupus) predation on caribou populations. We monitored radiomarked caribou, moose, and wolves between 1993 and 1997, and we found that selection of fen/bog complexes by caribou and selection of well‐drained habitats by moose and wolves resulted in spatial separation. This spatial separation in turn reduced wolf predation pressure on caribou but did not provide a total refuge from wolves. Any management activities that increase the density of moose and wolves or increase access of wolves into fen/bog complexes will likely reduce the refuge effect provided by large fen/bog complexes.
Woodland caribou in northeastern Alberta are relatively sedentary, occur at low densities, and are classed as endangered in Alberta. Increasing encroachment of the forest and petroleum industries into the southern regions of the boreal woodland caribou range has highlighted the need for detailed habitat analysis for this species. We obtained approximately 1000 locations of 47 woodland caribou fitted with very high frequency telemetry collars, providing data on winter habitat use from 1991 to 1994. Telemetry data were combined with digital peatland coverages that best represented lowland habitat diversity. Woodland caribou selected forested fen peatland complexes at both the population and individual spatial scales. Woodland caribou concentrated feeding activity in forested, raised bog islands. The raised bogs provide more xeric substrate for increased lichen biomass, possibly a key factor in their selection during winter. The hypothesized connection between discontinuous permafrost and the maintenance of raised bog islands in terms of caribou forage distribution and availability is discussed.
Landscape ecologists have been eager to make their research applicable to forest management. We examine how landscape ecology has contributed to shaping the way forest management is currently practiced. Landscape ecology research in forested ecosystems can be divided into two general areas: (1) the study of fragmentation issues, which focuses on the effects of forest fragmentation on species conservation; and (2) the development of landscape projection models, which focuses on patch dynamics and the effects of spatial arrangement of patches on ecosystem processes. Fragmentation issues have become priorities in the minds of forest managers, but research to date has over‐emphasized the effects of landscape structure on species conservation. We suggest that the research focus should move toward the study of threshold effects of landscape change on the relative influence of habitat loss and habitat configuration on species conservation in forest‐dominated landscapes. Landscape projection models are rapidly becoming important tools in forest management planning, and they hold great promise as a means to bring landscape ecologists and forest managers together. The ability to produce future landscapes under different management scenarios and to compare these to landscapes produced by natural disturbance regimes will help to focus both managers and scientists on understanding the key interactions among human activities, landscape features, and ecological processes.
Empirical descriptions of spatial overlap of coexisting herbivores are difficult to interpret in terms of functional interaction. In an attempt to obviate some of these difficulties, partial correlation analysis was applied to the study of habitat use behavior of whitetail deer, mule deer, elk, and bighorn sheep on an important wildlife winter-spring range in southeastern British Columbia. A probe was made of the basic determinants of habitat selection in order to isolate the response of represented species to the physical and vegetational environment and to summer grazing by cattle. Distinct patterns of habitat utilization were exhibited by each species. Whitetail and mule deer habitat preferences were distinguished from one another by elevation, ruggedness of terrain, and openness of forest and shrub vegetation. Elk were most widely distributed and showed the least apparent response to measured environmental parameters, whereas bighorn sheep were most localized and specific in their response to environment. Distributions of all species were only weakly influenced by the activities of grazing cattle at the level and pattern found on the study area. Partial correlation techniques appeared to offer some potential for analyzing resource division in mixed grazing systems. However, a number of technical and conceptual difficulties may limit their value in systems where reciprocal feedbacks, thresholds, and optima exist in the response of animals to environment. Numerous studies have attempted to provide measures of competition or ecological overlap among coexisting herbivores. Generally, competition has been described in terms of the extent to which members of a multispecies assemblage graze common areas during the same season and the extent to which they utilize common forage species (Julander, 1958). These parameters, in certain situations, may adequately describe the basic elements of competition when they are interpreted in relation to existing levels of
Woodland caribou (Rangifer tarandus caribou) in Alberta are classified as endangered and apparently have declined. Disturbance from petroleum exploration has been implicated as a possible cause, so we constructed a simple model to estimate the energy costs of multiple encounters with disturbance (i.e., loud noise). Our objective was to estimate if woodland caribou in northeastern Alberta have been exposed to enough disturbance from 1988 to 1993 to cause winter mass loss to exceed either (i) 15% autumn mass or (ii) 20% autumn mass. A single disturbance event costs caribou 3.46-5.81 MJ. Caribou would have to encounter (i) 20-34 (mean = 27) disturbance events to lose >15% mass over winter and (ii) 41-137 (mean = 89) events to lose >20% mass. There were five occasions from 1988 to 1993 (i.e., in a particular caribou distribution zone and winter) when the encounter rate (number of potential encounters per square kilometre) exceeded a level expected to result in caribou losing more than the estimated mean 15% autumn mass. There were four occasions when the encounter rate exceeded the lower limit expected to cause >20% mass loss and one occasion when it approached the mean rate expected to cause >20% mass loss. Modelling the cumulative influence of disturbances demonstrates an effect on individual energy loss during winter at certain exploration intensities. It is the first attempt at estimating the consequences of petroleum exploration for wildlife in northeastern Alberta and provides important information for future research and land-use management.Résumé : En Alberta, la population du Caribou des bois (Rangifer tarandus caribou) est réputée en voie de disparition et elle est effectivement en déclin; les perturbations occasionnées par les opérations pétrolières y contribuent probablement. Nous avons construit un modèle mathématique simple qui permet d'estimer les coûts énergetiques associés aux instances multiples de telles perturbations (notamment le bruit intense). Nous avions pour objéctif d'estimer si la population a subi suffisamment de perturbations entre 1988 et 1993 pour occasionner une perte de masse en hiver supérieure (i) à 15% de la masse à l'automne ou (ii) à 20% de la masse à l'automne. Une seule perturbation coûte à un caribou de 3,46 à 5,81 MJ. Un caribou doit donc être soumis à (i) entre 20 et 34 (moyenne = 27) perturbations pour perdre plus de 15% de sa masse en hiver et (ii) à entre 41 et 137 (moyenne = 89) perturbations pour en perdre plus de 20%. Entre 1988 et 1993, il y a eu cinq circonstances (i.e., dans une zone de répartition particulière et au cours d'une saison précise) où le taux des perturbations (nombre de perturbations potentielles par kilomètre carré) a été plus élevé que le nombre théorique susceptible d'engendrer une perte moyenne de masse de plus de 15% en hiver. Il y a eu quatre circonstances où ce taux a dépassé le seuil inférieur susceptible de provoquer une perte de masse de plus de 20% et une seule circonstance où il s'est approché du taux moyen relié à une perte de masse de plu...
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