Ecological significance of litter redistribution by wind and snow in arctic landscapes

Abstract

During winter in the Arctic, plant litter is scoured from exposed hills and ridges by wind and snow and is redistributed to other portions of the landscape. The aim of this research was to quantify the physical and biological consequences of this litter redistribution. Litter biomass accumulation was ten times greater in areas of high deposition (e.g., snow drifts) than in areas of low deposition. Spring snow melt was delayed by several days and soils were cooler throughout the growing season and throughout winter in areas of increased litter deposition than areas with no litter. Photosynthetically active radiation (PAR) was reduced to near zero with small accumulations of litter. Annual C and N inputs from allochthonous litter were 143 g C m-2 and 14 g N m-2 in high litter areas and 3.4 g C m-2 and 0.3 g N m-2 in non-drift, ambient litter deposition areas. Although PAR and soil temperatures were significantly reduced with increased litter deposition, we did not observe significant delays in key plant phenological events of several species or measure a decrease in gross ecosystem photosynthesis. We did measure a significant increase in ecosystem respiration with increased litter deposition, which resulted in a shift in the net C balance of dry heath tundra from near zero with no litter to a net source of CO2 to the atmosphere. Our study indicates that the redistribution of litter by wind and snow during winter is an important mechanism of nutrient transfer across the arctic landscape and that allochthonous litter inputs are of great enough magnitude to alter the carbon balance of some areas of the arctic landscape.