Comparing Alternative Management Strategies of Fire, Grazing, and Weed Control Using Spatial Modeling

Authors: PROVENCHER, LOUIS - THE NATURE CONSERVANCY; De Queiroz, Tara; FRID, LEONARDO - ESSA TECHNOLOGIES; MEDLYN, GARY - BUREAU OF LAND MANAGEMENT

Submitted to: Ecological Modelling
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2007
Publication Date: 8/13/2007
Citation: Provencher, L., Forbis, T.A., Frid, L., Medlyn, G. 2007. Comparing alternative management strategies of fire, grazing, and weed control using spatial modeling. Ecological Modelling. 209:249-263.

Interpretive Summary: Estimating the effects of multiple factors in land management is a difficult task, particularly when there is controversy surrounding management tools such as livestock grazing, prescribed fire, and the application of herbicides on public lands. Spatial modeling is one tool that can allow public lands managers, users, and other interest groups to conduct systematic comparisons of land management strategies and view projected management results on maps of the landscape of interest. In this paper, we report on efforts by a collaborative group to compare 6 different management scenarios over 20 years on a large (>350,000 acres) public lands management area in eastern Nevada. Management scenarios tested differed in their use of prescribed fire and suppression of natural fires, livestock grazing, mechanical fuels treatments of vegetation and the use of herbicides to control invasive weeds and native woody plants. The levels of restoration treatments in the scenarios were based on the Ely, Nevada Bureau of Land Management’s restoration budget, and incremental increases in that budget. After 20 years, we found that even with budget increases, differences among different management scenarios were small due to the large acreage of degraded shrublands and woodlands. However, restoration treatments were able to effectively maintain good-condition sites that would otherwise have been lost. We found that varying livestock grazing made little difference, and that mechanical and chemical restoration treatments, though expensive, were effective in maintaining good condition vegetation.

Technical Abstract: Modeling can be used to resolve controversies generated by differing opinions about the effects of livestock grazing, fire management, and herbicide application on western public lands. We used spatial simulations of 10 potential vegetation types to compare 6 management scenarios over 20 years in a 141,853 hectare landscape in eastern Nevada. Scenarios were compared by incrementally varying one factor at a time and were based on the Bureau of Land Management’s (BLM) potential restoration plans. The following factors were varied: managed fire, livestock grazing, mechanical and chemical treatment of vegetation, and restoration budgets. After 20 years the differences in vegetative composition between scenarios were small. BLM’s level of funding was too low to improve ecological condition because the landscape was too degraded, however, current funding could maintain communities that retained native perennial understories. In general, the effects of livestock grazing were minor and undesirable compared to benefits gained from the use of mechanical and chemical methods followed by seeding. Mechanical methods and herbicide application in addition to current fire management had more desirable effects than without it.