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Historical Fire Regimes of Wyoming and Basin Big Sagebrush Steppe on the Snake River Plain

Background

The fire histories of sagebrush-dominated vegetation types are difficult to document with traditional methods such as utilizing multiple fire scars or macroplot population demographic composition. Individual sagebrush plants do not fire scar and a fire usually removes all sagebrush plants within the burned area. In some areas sagebrush steppe fire history has been extrapolated from adjacent vegetation types that contain conifer species that are scarred by fire (e.g., western juniper (Juniperus occidentalis), ponderosa pine (Pinus ponderosa), Douglas fir (Pseudotsuga menziesii). These species, however, are largely not available for most of the Snake River Plain.

There is an urgent need for understanding the relationship between seasonal climate patterns and large fire potential in sagebrush steppe, as little information is available on the relationship of climate and fire size for sagebrush ecosystems. As the impact of climate variability and extreme climatic events on fire occurrence and size can vary depending on scales at which they are analyzed, fire history is being reconstructed across multiple spatial scales, with the INL Site at the finest scale. Studies of fire history and ecology are vital to understanding and forecasting the impacts of climate change on sagebrush steppe ecosystems. An improved understanding and the ability to forecast future impacts can serve as the scientific foundation upon which fire and land management decisions can be based.

Objectives

There are few studies of fire history in the sagebrush steppe and none that examine the changes in occurrence of large fires (5000+ acres) and consecutive climatic conditions. The specific objectives of this research are to:

  1. Reconstruct the fire history (1960-2003) for sagebrush steppe ecosystems across three spatial scales of sagebrush-dominated steppe: a. Idaho National Laboratory Site, b. Snake River Plain, and c. portions of the Northern Basin and Range to include the Snake River Plain;
  2. examine the links between climate and large fire events in sagebrush-steppe vegetation by investigating a range of potentially important climatic variables (e.g. drought, ENSO and PDO); and
  3. Develop predictive models to assess how climate variation will affect fire frequency and size characteristics within sagebrush steppe ecosystems.
     

Accomplishments Through 2007

  • Downloaded climate data (Daymet) for future analyses

  • Secured vegetation coverage of area (GAP)

  • Collected and compiled various historical fire data into a GIS layer

  • Obtained and averaged climate data into monthly, seasonal divisions, and annual divisions

  • Modified precipitation and temperature to use Western Regional Climate Center (WRCC) data to extend full range of dates of fire history (1960-2003)

  • Compiled Palmer Drought Severity Index (PDSI) data for study areas into spreadsheet

Results

Because data collection was not initiated until 2007 and no data analyses have yet been compiled, no results are reported here.

Plans for Continuation

In 2008, we plan to complete the data analysis and report preparation. To investigate the probability of future regional fire years in sagebrush steppe in response to changes in climate, six hypothetical scenarios are currently being used, where each scenario is simulated as a departure from baseline mean temperature and precipitation. These six scenarios were derived using three downscaled general circulation models and the Intergovernmental Panel on Climate Change A2 and B1 scenarios, which simulate the upper and lower limits of projected greenhouse gasses, respectively. The probabilities of future regional fire years in sagebrush steppe under different climate scenarios are being examined.

Publications, Theses, Reports, etc.

No publications have resulted from this research at this time. We anticipate completion of M.S. thesis during this current year


Investigators and Affiliations

Stephen C. Bunting, Professor of Rangeland Ecology, Department of Rangeland Ecology and Management, University of Idaho, Moscow, Idaho

Andréa L. Kuchy, Graduate student, Department of Rangeland Ecology and Management, University of Idaho, Moscow, Idaho

Funding Sources

U.S. Department of Energy Idaho Operations Office

University of Idaho, College of Natural Resources, Department of Rangeland Ecology and Management, Moscow, Idaho

 


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