Alaska Section, American Water Resources Association

Richard Kemnitz, Alaska Section AWRA Northern-Region Director

I would like to invite you to the October 2001 Brown-Bag presentation by Bob Bolton. Please note this meeting is the second Wednesday in October. We look forward to seeing you, please feel free to bring a colleague to the meeting.

October 10, 2001
Alaska Section AWRA, Northern-Region Brown-Bag Presentation
Alaska Department of Natural Resources, Large Conference Room
Noon to 1300

"Short- and Long- Term Effects of Wildfire on Soil Moisture Content in Interior Alaska"
William R. Bolton

Water and Environmental Research Center
University of Alaska Fairbanks
Fairbanks, Alaska 99775

William R. Bolton, Kenji Yoshikawa, and Larry D. Hinzman,
(Water & Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK, 99775, fteky@uaf.edu)

Abstract

Wildfires are a natural part of the boreal forest ecosystem history. Fires in the boreal forest have both immediate and long-term impacts on the ecosystem due to its effects on the surface energy, water balance, and underlying permafrost. Hydrologic processes affected by wildfire (primarily through the removal of vegetation) include snow accumulation and snowmelt, storm flow response, stream base flow, soil moisture, permafrost aggradation and/or degradation, and erosion.

The purpose of our research is to investigate short- and long-term relationships between the ground thermal regime and soil moisture content in areas affected by wildfire in Interior Alaska. Our research is guided by the hypothesis that in areas of discontinuous permafrost, wildfire affects the ground thermal regime and the soil moisture content. The short-term effect of fire results in increased ground temperature and soil moisture content. The long-term effect is an increased ground temperature and decreased soil moisture content. The magnitude of change (both short- and long-term) in ground temperature and soil moisture content is proportional to the fire severity. Changes in the thermal and soil moisture regime can lead to a new favored vegetation. Results from eleven wildfire sites throughout Interior Alaska, ranging with dates of ignition from 2000 to the 1920s, will be presented.

Figure 1. Conceptual model of our hypothesis on Short- and Long- Term Effects of Wildfire on Soil Moisture Content

Figure 2. Area burned in Alaska from 1957 through 2000.