Dendroecological assessment of tree island growth trends and patterns in the Cavell Meadows, Jasper National Park, Canadian Rocky Mountains

Dendroecological studies in the western cordillera of Canada and the United States of America have revealed that the character and location of many climatically-controlled treelines have changed dramatically within the last century. This presentation illustrates the results of an analysis of tree islands located within a treeline ecotone in the Cavell Meadows, Jasper National Park (JNP), Alberta. Historical photographs show tree cover increasing and previous assessments of seedling establishment within the region suggest these changes are climatically controlled. Past research has shown changes in the alpine treeline ecotone are characterized by a movement from tree islands to patch-forest morphs. The goal of our study was to discern which ecological mechanisms were driving the expansion of the subalpine fir (Abies lasiocarpa) tree islands into the surrounding alpine meadows in Cavell Meadows. Periods of stem establishment within the meadows were found to correspond with periods of above average radial growth of trees in the continuous forest. Consistent with previous research, we discovered that the radial growth of subalpine fir trees in Cavell Meadows was negatively correlated with past summer air temperatures. Based on the findings of our investigations, we offer a prediction of the future of tree island expansion in Cavell Meadows