Mechanisms and feedback consequences of shrub expansion following long-term increases in winter snow depth in northern Alaska: a legacy for IPY

University Of Alaska Anchorage Campus, Anchorage AK

Investigators

Abstract

Welker - 0612534 Funds are provided for a detailed, mechanistic investigation of how shrubs become dominant in response to snow depth increases - a process that has been observed to occur in Alaska. This study will quantitatively document how increases in shrubs have altered the abiotic environment and caused a fundamental change in the functional attributes of these systems in arctic Alaska. The specific goals of this project are to: 1. quantitatively document how shrub increases affect the year-long temperature and water regimes of arctic tundra and how shrub increases change the energy balance of the system; 2. delineate the processes controlling shrub increases, especially soil and plant nitrogen cycling and the physical protection of shrub meristems and branches by deeper snow; and 3. quantitively describe how shrub density increases have affected the patterns and magnitudes of carbon [C] cycling [C gain, C loss and C allocation], water sources and growth, both aboveground and belowground. Observed shrub expansion within portions of arctic Alaska may have significant consequences, including shifts in the albedo-climate feedback, altered animal abundances, and changes in carbon and nitrogen cycling processes. As warming is progressing at a rapid rate in Alaska, a mechanistic understanding of the biotic response is needed, if informed land use decisions are to be made and if accurate forecasting models are to be developed.