Submitted to: International Rangeland Congress
Publication Type: Proceedings
Publication Acceptance Date: July 23, 1995
Publication Date: N/A
Interpretive Summary: Resource values are impaired or threatened on millions of acres of public rangeland in the Great Basin and Columbia Plateau. A major contributor to resource degradation on these lands is the presence of annual weedy species that proliferate after wildfire. The Bureau of Land Management estimates that, in Idaho alone, over 1 million acres of sagebrush/bunchgrass rangeland have been converted to a monoculture of cheatgrass. An additional 1.8 million acres that contain cheatgrass in the understory are at risk of conversion after wildfire. Burn-rehabilitation plans by public land management agencies currently rely on gross approximations of species adaptation to mean annual precipitation and soil texture. This approach does not take into account: the seasonal distribution of precipitation; year-to-year variability in climatic variables; dynamic processes of heat and water transfer in the seedbed; or species-specific microclimatic requirements for seed germination, emergence and establishment. The NWRC has undertaken a research program to identify technically feasible management options for re-establishment of desirable Intermountain grasses and shrubs in areas currently dominated by annual weeds. In support of this goal, the NWRC is developing modeling tools to simulate post-burn seedbed temperature and moisture for given patterns of weather input. From this information it may be possible to design optimal planting scenarios for establishment of desirable native species and to develop mitigating strategies to minimize competition from cheatgrass.
Technical Abstract: A major contributor to resource degradation on western rangelands is the prevalence and expansion of populations of undesirable non-native annual weeds after wildfire. Critical factors determining the success of reseeding efforts are the spatial and temporal distribution of soil heat and moisture relative to the establishment requirements of both desirable species and weedy competitors. Burn-rehabilitation plans currently rely on gross approximations of species adaptation to mean annual precipitation and soil texture. This approach does not take into account: the seasonal and yearly variability in macroclimatic variables; topographic and edaphic effects on seedbed microclimate; and the inter and intraspecific variability in growth response of desirable and undesirable plant species. The ARS NWRC is developing technology to characterize seedbed microclimatic variability as it pertains to the restoration and maintenance of native plant communities in the sagebrush/bunchgrass vegetation type. This program includes development of technology to characterize climatic variability, seedbed microclimate, and seedling establishment response of both native and introduced grasses and shrubs. The program utilizes a process-based modeling approach and emphasizes validation of system components and adaptability to accommodate advances in technology. The goal of the program is to develop better technology to evaluate the potential success of restoration management strategies.