Restoration Initiatives
Tracking cheatgrass spread within the Warm Fire burn area
The Warm Fire burned 58,000 acres of the central and eastern portions of the Kaibab Plateau. Given the high likelihood of cheatgrass invasion at lower elevations of the burn area, our volunteers are working with the Forest Service to map the distribution of cheatgrass along the low-elevation eastern perimeter of the Warm Fire.
Introduction
In June, 2006 the Warm fire escaped its “wildland fire use” boundary, eventually burning approximately 58,ooo acres of Ponderosa Pine, Mixed Conifer and Piñon-Juniper forest on the Kaibab Plateau, including a large portion of the Kane Ranch. Despite the Warm fire’s exceptionally large size, its effects on the landscape are not entirely unpredictable. In 1996, the Bridger-Knoll fire burned approximately 50,ooo acres on the west side of the Plateau. Beyond its immediate short-term effects, the Bridger-Knolls fire facilitated a large-scale invasion by cheatgrass (Bromus tectorum), across tens of thousands of acres of important mule deer winter range.
The Warm fire extended over a dramatic elevational gradient, ranging from about 6300 to 9000 ft. Recent experience indicates that fire plays dramatically different ecological roles across the Plateau, depending on numerous factors including elevation, vegetation type, and forest condition. At lower elevations (5000-7000 feet), the effects of the Bridger-Knoll fire have been significant and largely negative, facilitating the spread of cheatgrass and other noxious weeds species. Given similarities in soils, vegetation, and elevation along the eastern perimeter of the Warm fire to invaded areas within the Bridger-Knoll burn perimeter, we believe that the eastern perimeter of the Warm fire is likely to be at the greatest risk of invasion by non-native species.
Approach
In April and May 2007 we initiated a comprehensive survey to assess the distribution and abundance of cheatgrass along the eastern perimeter of the Warm Fire in the first year post-fire in order to identify high-priority areas for monitoring post-fire cheatgrass invasion on the Kaibab Plateau. The study was targeted toward the lower elevation perimeter of the Warm Fire burn area, as this may be the most likely point of entry for cheatgrass.
Field technicians and over 60 volunteers collected observations of cheatgrass presence, percent cover, and ground cover characteristics from 278 circular plots (168m2) that were located 400 m from the burn perimeter. Half of these plots were located in the burned area, while the other half were outside the burn area. Observations of cheatgrass presence and percent cover were also recorded at 4195 transect locations. We integrated these data with GIS coverages of roads, burn severity, soil type, slope, and elevation in order to extract patterns of invasion at a landscape scale.
We have completed some preliminary analyses of these data and have revisited the majority of plots in spring of 2008. Our data indicate that cheatgrass invasion had already begun to occur within the fire perimeter, one year post-fire. Cheatgrass was observed more frequently inside the fire perimeter than outside, but other patterns of invasion were difficult to discern. Cheatgrass occurred in all of the dominant soil types, and was observed at elevations up to about 7500 ft and on slopes up to 85%. Cheatgrass occurrence and percent cover did not show a strong relationship to distance from roads, but high cover values were frequently observed near roads.
Future Work
We have provided this perimeter assessment data to the U.S. Forest Service, and are working with Forest Service staff to identify areas of highest priority for re-seeding and rehabilitation work. We intend to work with U.S. Forest Service staff and volunteers over the coming spring and summer months to pursue such rehabilitation priorities, focusing on collectively identified “hot zones”. Rehabilitation activities will center on native species re-seeding and strategic control of cheatgrass spread using limited herbicide application.
