Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2003
Publication Date: 11/1/2004
Citation: Hardegree, S.P., Van Vactor, S.S. 2004. Microclimatic constraints and revegetation planning in a variable environment. Weed Technology 18:1213-1215.
Interpretive Summary: Millions of acres of sagebrush-bunchgrass rangeland have been replaced by cheatgrass in the Intermountain western United States. Restoration of these systems with desirable native plant species is hindered by high variability in rainfall from year to year and funding constraints that limit revegetation activities to post-fire rehabilitation efforts. Historical rainfall data and computer models were used to analyze historical probabilities of favorable conditions for establishment of native plants. It was determined that revegetation and restoration strategies could be optimized by separating emergency-rehabilitation and restoration objectives, consideration of non-native plant materials in dry years, and addressing restoration needs only in years when establishment of native plants would be feasible. It was also suggested that non-native plants should be considered as an intermediate plant community in restoration of native sagebrush-steppe vegetation. Utilization of weather data and forecasting could reduce the cost of revegetation and restoration and increase the probability of success by focusing efforts on time periods where there is a reasonable expectation of success.
Technical Abstract: Water availability is a primary determinant of successful plant establishment on western rangelands. Two major factors that determine water availability are seasonal and annual patterns of precipitation, and the presence of competitive annual weeds. Seedbed-microclimate and germination-response models can be used to evaluate alternative management treatments and plant materials; and to incorporate medium and long-term weather forecasts into real-time management planning. In order to take full advantage of these tools it is necessary to separate short-term soil-stabilization, and longer-term biodiversity and restoration objectives. Emergency rehabilitation policies prioritize establishment of plants that will both stabilize the soil and compete successfully with invasive weeds. Weather-forecast information and modeling may be more useful to longer-term restoration planning where revegetation and weed-control actions can be deferred to coincide with a favorable microclimatic forecast.