1. A Decade of Dwarf Birch Growth across a Canadian Low Arctic Landscape: Exploring the Impacts of Climate Change

Abstract

Climate change predominantly affects northern regions, and resultant vegetation change (particularly the expansion of arctic shrubs) has the potential to create large-scale, positive climate feedbacks, including the widespread release of CO2 from arctic soils. Understanding the intensity and distribution of arctic shrub expansion is therefore necessary to predict future climate trajectories. Few studies, however, have directly measured vegetation changes in the Canadian continental low Arctic, and similarly, there is a need to better understand the landscape-level factors that determine shrub growth responses to warming. Previous studies in Alaska indicate strong differences in shrub growth responses between habitat-types, attributed to higher nutrient and water supply in low-lying areas. Therefore, this study examines growth patterns of the dominant shrub (Dwarf Birch, Betula glandulosa) in a variety of habitat-types across a low arctic landscape.
 Significant increases in both shrub cover and stature over ten years were found, but surprisingly there were no differences in growth between habitat-types. Further analyses (pending) will measure inter-annual shrub growth to compare patterns/degrees of variability between habitat-types. Individual shrub growth rates over the past decade correlated to local soil nutrient concentrations, but no other variables, suggesting that local spatial variation in nutrient availability seems to be the primary factor determining shrub growth responses to climate change. Overall, our preliminary results stress the importance of local nutrient variability in controlling shrub responses to warming, and challenge previous studies indicating strong differences in shrub growth responses to warming among habitat-types.