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:
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;
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
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
