Winter Biological Processes Could Help Convert Arctic Tundra to Shrubland

In arctic Alaska, air temperatures have warmed 0.5 degrees Celsius (C) per decade for the past 30 years, with most of the warming coming in winter. Over the same period, shrub abundance has increased, perhaps a harbinger of a conversion of tundra to shrubland. Evidence suggests that winter biological processes are contributing to this conversion through a positive feedback that involves the snow-holding capacity of shrubs, the insulating properties of snow, a soil layer that has a high water content because it overlies nearly impermeable permafrost, and hardy microbes that can maintain metabolic activity at temperatures of -6C or lower. Increasing shrub abundance leads to deeper snow, which promotes higher…

• NS
  National Science Foundation
• DO
  Division of Arctic Sciences