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Resource development can have significant consequences for the distribution of vegetation cover and for species persistence. Modelling changes to anthropogenic disturbance regimes over time can provide profound insights into the mechanisms that drive land cover change. We analyzed the spatial patterns of anthropogenic disturbance before and after a period of significant oil and gas extraction in two boreal forest subregions in Alberta, Canada. A spatially explicit model was used to map levels of anthropogenic forest crown mortality across 700 000 ha of managed forest over a 60-year period. The anthropogenic disturbance regime varied both spatially and temporally and was outside the historical range of variability characterized by regional fire regimes. Levels of live forest crown within anthropogenic disturbances declined and edge density increased following oil and gas development, whereas patch size varied regionally. In some places, anthropogenic disturbance generated profoundly novel landscapes with spatial patterns that had no historical analogue in the boreal system. The results illustrate that a shift in one sector of the economy can have dramatic outcomes on landscape structure. The results also suggest that any efforts to better align cumulative anthropogenic disturbance patterns with the historic baseline will almost certainly require a concerted and collaborative effort from all of the major stakeholders.Résumé : L'exploitation des ressources peut avoir d'importantes conséquences sur la répartition du couvert végétal et la persistance des espèces. La modélisation des changements temporels dus aux régimes de perturbation anthropique peut déboucher sur une meilleure connaissance des mécanismes qui déterminent les modifications du couvert végétal. Nous avons analysé la configuration spatiale des perturbations anthropiques avant et après une période durant laquelle une quantité importante de pétrole et de gaz a été extraite dans deux forêts boréales en Alberta, au Canada. Un modèle spatialement explicite a été utilisé pour cartographier le niveau de mortalité d'origine anthropique dans le couvert forestier sur un territoire de forêt aménagée de 700 000 ha pendant une période de 60 ans. Le régime de perturbation anthropique a varié dans le temps et l'espace et excédait les limites historiques de variabilité caractérisées par des régimes de feu régionaux. Les niveaux de couvert forestier vivant dans les zones de perturbation anthropique ont diminué et la densité de lisière a augmenté à la suite de l'exploitation du pétrole et du gaz tandis que la dimension des parcelles de forêt variait selon la région. À certains endroits, les perturbations anthropiques ont engendré des paysages totalement nouveaux dont la configuration spatiale n'avait aucun équivalent dans l'histoire du système boréal. Les résultats illustrent le fait qu'un changement dans un secteur de l'économie peut avoir des effets dramatiques sur la structure du paysage. Les résultats indiquent aussi que toute tentative visant faire en sorte que la c...

The strategy of managing for “natural” patterns towards ecological sustainability of forests is currently limited lo simple spatial attributes of landscapes. Yet, there is general agreement that landscapes are highly dynamic entities suggesting that temporal patterns may also he important. This study used historical estimates of 20‐yr disturbance rates, and a spatially explicit, stochastic landscape model to create multiple possible landscape mosaic scenes for three different landscapes in the foothills of Alberta, The results were summarized as frequency distributions by age‐class, and the distributions compared to the percentage of area in the current, and the pre‐commercial landscapes. Results indicated that aside from one age‐class in one of the landscapes, both current and pre‐commercial age‐class distributions were well within the historical ranges suggested by the simulations. More generally, the simulations indicated relatively high, but landscape specific, levels of historical temporal variability. This implies that there are patterns to temporal variability which may be captured, quantified, and emulated as alternatives to single age‐class management targets. The research also demonstrates a method of assessing age‐class distributions within the context of historical ranges of distributions.

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