Energy budget changes following surface disturbance to upland tundra

Haag, Richard; Bliss, L

The effects of three types of surface disturbance (winter road, fire, and oil spill) on the radiant energy budget of upland low shrub-heath tundra were investigated. All disturbances to vegetation or the soil surface resulted in an albedo reduction, which led to a direct increase in net radiation. Despite the increase in net radiation, latent heat loss decreased on all disturbances due to vegetation removal and loss of access to sub-surface soil moisture. Latent heat loss from disturbed surfaces was dependent on surface moisture levels. The decrease in latent heat loss upward resulted in an increase in soil heat flux, soil temperatures, and depth of the active layer. Undisturbed peat with high water content provides good thermal insulation on the surface and acts to decrease rate of soil thaw. Where peat was removed, mineral soil thawed at a rapid, nearly constant rate, and thaw depth exceeded control values by over 50% at the end of the summer. Such an increase can in turn lead to surface subsidence and, a further increase in resistance to latent heat loss resulting from thicker boundary layer conditions over the disturbed surface. Re-seeding acts to increase rate of albedo recovery following disturbance. However, if litter is not replaced, increased plant cover has little effect on active layer depth during the first 3 years of re-growth.

Energy budget changes following surface disturbance to upland tundra

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