Plant Communities to Curb Climate Warming in Arctic and Alpine Environments
Warmer temperatures in the arctic, especially in mountainous regions, have led to reduced snow cover and longer growing seasons for shrubs and other plants. These environmental changes affect local ecological communities, but can also influence broader atmospheric conditions. For instance, because snow reflects more sunlight than barren ground or vegetation, reductions in snow cover may increase the amount of energy absorbed by the earth’s surface and ultimately raise temperatures. As a result, warming can create a positive feedback loop, where higher temperatures cause land cover changes, which cause more warming, which further alters land cover, and so on.
One factor likely to influence the potential feedback between land cover and climate is the proportion of light reflected by the surface, or albedo, of different vegetation types. To assess variations in albedo, researchers from the University of Alberta took a series of measurements at locations with different plant communities in the sub-arctic mountains of south-west Yukon. They found that sites generally became more reflective as new foliage spread over the growing season, partially offsetting the heating effect of earlier snow melt. There were also large differences in albedo among vegetation types. Plant communities with short flat shrubs had the highest reflectivity, while dense canopies of taller shrubs had the lowest. These results show that future warming will depend, in part, on how different shrub species expand into our changing arctic and alpine environments. As the shorter and more reflective shrubs are predicted to dominate under warmer conditions, this study suggests that northern and high elevation ecosystems may naturally respond to higher temperatures in a way that actually curbs further warming.
This is a summary article authored by Charlie Loewen. For further information, please see the original published research:
Scott N. Williamson, Isabel C. Barrio, David S. Hik & John A. Gamon (2016) Phenology and species determine growing-season albedo increase at the altitudinal limit of shrub growth in the sub-Arctic. Global Change Biology, 22:3621–3631 (doi:10.1111/gcb.13297).