Description
Summary:We have conducted experimental manipulations of shrub canopies in the south-western Yukon. For the 12 shrub and 12 tundra plots, we have measured soil temperatures, snow depths, soil profiles, carbon dioxide effluxes, plant available nitrate and ammonia, tundra and shrub biomass, and percent carbon and nitrogen in soils and plant biomass. We have also collected shrub growth ring data and ages for willows from 20 sites in the Kluane Region and other sites in the Yukon. : Purpose: With a warming climate, Arctic ecosystems will experience shifting boundaries such as the spread of tall shrubs into tundra communities. Rapid shrub expansion has been documented in Arctic Alaska and north-western Canada using repeated aerial photography, and satellite imagery. Increasing shrubs could alter the soil thermal regime and reflectance of the tundra ecosystem. In the winter, snow trapping can insulate soils, and has been proposed as a positive feedback mechanism for promoting the expansion of shrubs in the Arctic. : Summary: Not Applicable