Natural and Assisted Recovery of Sagebrush in Idaho’s Big Desert:  Effects of Seeding Treatments on Successional Trajectories of Sagebrush Communities.

Cheatgrass (Bromus tectorum)

Averaged over the last ten years, approximately 235,000 acres of lands managed by the BLM in Idaho have burned annually. The BLM and other managers of Idaho rangelands, including the Idaho National Engineering and Environmental Laboratory (INEEL), must decide whether the burned areas need stabilization and rehabilitation treatments to prevent soil erosion and inhibit the invasion of exotic species such as cheatgrass (Bromus tectorum).  Most of these rangelands have historically been dominated by big sagebrush (Artemisia tridentata), which does not re-sprout after fire. Sagebrush provides critical food and habitat for sage grouse, a species in serious decline over much of its range and considered a species of concern by the U. S. Fish and Wildlife Service. With the accelerating loss of native sagebrush communities and habitat for sage grouse and other sagebrush-obligate species, sagebrush reseeding following fire has become an important consideration, as has the issue of livestock grazing impacts on recovering native vegetation and seeded areas. In the last three years approximately 70% of the sage grouse habitat in eastern Idaho’s Big Desert has been burned by wildfire. Fire suppression and rehabilitation costs are rising, and the threats to human life and property are increasing in eastern Idaho.

Aerial sagebrush reseeding

This study has been divided into three components to address management concerns relative to 1) native plant recovery in good ecological condition rangeland, 2) success of aerial seeding sagebrush and 3) whether livestock grazing effects native plant recovery on good condition rangeland. The evaluation of good condition Wyoming big sagebrush/bluebunch wheatgrass rangeland after wildfire presents a unique opportunity to document the recovery of the vascular plant and biological crust communities. This information will be used to help managers determine if areas need to be treated following wildfire (vs. allowing natural recovery) and to document trajectories of vegetation change following a wildfire on good ecological condition rangeland. Opportunities to evaluate the natural progress of succession on good condition sagebrush steppe rangelands after a wildfire are very rare in southern Idaho due to the increasing dominance of cheatgrass and other invasive species.

Big Sagebrush  (Artemisia tridentata)

The second component of the study focuses on the efficiency (economical as well as biological) of artificially seeding sagebrush compared to natural shrub reestablishment on good condition rangeland. Observations and some studies on past fires in this area indicate that native grasses have fully recovered but sagebrush recruitment is still lacking. This study provides the opportunity to determine if sagebrush seeding effectively “jump starts” reestablishment of shrubs on burned rangelands. It also provides baseline studies to assess the long-term timeframes associated with sagebrush recovery on burned good condition rangeland where artificial seeding is not applied.

The third component of the study provides information on whether livestock grazing, after the BLM’s required exclusion period of two growing seasons, affects the recovery and persistence of vascular plants and biological crusts. This information will assist managers in refining guidelines on livestock grazing timeframes and will document invasive species (including but not limited to cheatgrass) increases on grazed and ungrazed rangelands after a wildfire. Since there is a great deal of controversy about the length of the period that grazing should be excluded following wildfire, this component of the study will provide scientific data to refine the current policy relative to invasive species and recovery of native vegetation.

Sage Grouse

In summary, the three components will provide new scientific information that addresses current management concerns relative to wildfire impacts and rehabilitation treatments on the eastern Snake River Plain. These studies are designed to establish long-term, replicated monitoring sites that can be reread in the future to provide additional information to managers relative to post-fire recovery and rehabilitation success. These studies will also provide insight into restoring sagebrush and understory herbaceous species for sage grouse and other sagebrush obligate wildlife species and domestic livestock in the Great Basin.

Project Results

Project results will be posted on the ESER website as they become available.