BOISE — The practice of emergency post-fire seeding in sagebrush landscapes of the Great Basin, which was meant to stabilize soils, has not resulted in restored habitats that would be used by greater sage-grouse according to U.S. Geological Survey and U.S. Forest Service researchers who published their results today in the journal Ecosphere.
The new study examined the habitat that was present 8-20 years after the seeding projects occurred. These aerial or rangeland drill seeding projects did not always include sagebrush seeds and were not intended to restore wildlife habitat, but instead were designed to mitigate the effects of fire on soil and vegetation. Yet they provide an opportunity to reverse habitat degradation for sage-grouse, a species being considered for protection under the Endangered Species Act.
Scientists first characterized which habitats and landscapes sage-grouse use throughout the Great Basin. Then they examined areas that had burned and were subsequently seeded with rangeland plant species between 1990 and 2003. To link the two phases of the study, the authors assessed whether vegetation conditions in rehabilitated areas were similar to the habitats used by sage-grouse.
The authors found that sage-grouse tend to use areas with a mixture of dwarf sagebrush and Wyoming big sagebrush, native grasses, minimal human development, and minimal non-native plants. This information will help land managers prioritize areas for protection from disturbance or areas for future sage-grouse specific restoration efforts.
"When we compared these vegetation and landscape conditions to those of post-wildfire rehabilitation sites, we found that the probability of sage-grouse using treated areas was low and not very different from burned areas that had not been treated," said USGS ecologist Robert Arkle, the lead author of the publication.
Burned areas, whether treated or not, generally lacked shrubs even after 20 years, and in low elevation areas especially, non-native plants like cheatgrass were often too prevalent for burned sites to be used as sage-grouse habitat. This is important because it means that for at least 20 years following wildfire, burned areas of the Great Basin are not likely to be used by sage-grouse, regardless of emergency stabilization treatment. With this kind of time lag, a substantial amount of sage-grouse habitat is lost each year to wildfire, while gaining relatively little through natural plant succession or emergency stabilization treatments.
Published guidelines about what constitutes sage-grouse habitat also provided criteria for comparison to what the scientists observed in the seeded sites. Seeded areas met habitat guideline criteria for native grasses about half of the time, but the majority of seeding projects did not meet sagebrush or forb guideline criteria.
Some individual seeding projects did result in higher quality habitat and the authors evaluated the environmental conditions shared by these sites to determine where post-fire rehabilitation is more likely to benefit sage-grouse. Seeding projects that were most effective tended to occur in cool, moderately moist climates and also depended on post-treatment precipitation and surrounding landscape conditions.
"This is part of a growing body of science demonstrating how difficult it is to rehabilitate sagebrush landscapes once native vegetation is lost through wildfire," said USGS ecologist David Pilliod, who co-authored the publication. "Restoration in the Great Basin is a huge challenge for land managers not only because of difficulties associated with reducing non-native plants and establishing natives, but also because of the rate at which landscapes with sagebrush and other native vegetation are lost. These habitat losses can have negative consequences for sage-grouse and other wildlife that depend on sagebrush."
The study found that even relatively small amounts of non-native plants and human development were both forms of habitat loss that affected whether sage-grouse would use particular locations.
Although these projects did not specifically target sage-grouse, they are important sage-grouse conservation opportunities, according to Arkle. This is because wildfires burn about one million acres each year in the Great Basin and 97 percent of the acres treated by these projects are in historic sage-grouse habitat.
This research was conducted in collaboration with the Bureau of Land Management and the Joint Fire Science Project. Funding was provided by the U.S. Geological Survey, the Bureau of Land Management, and the U.S. Forest Service. The study, Quantifying restoration effectiveness using multi-scale habitat models- implications for sage-grouse in the Great Basin, published in Ecosphere is an offshoot of a larger effort to assess ecological outcomes of emergency stabilization and rehabilitation projects conducted by federal land managers in the Great Basin.