HOW MUCH SAGEBRUSH IS TOO MUCH - AN ECONOMIC THRESHOLD ANALYSIS

Much research concerning sagebrush control methods and forage response after control has been conducted due to the importance of sagebrush-grass dominated rangelands for livestock and wildlife in the western United States. Very little research has addressed the economic feasibility of sagebrush control at various levels of abundance. This study estimates the economic threshold abundance of sagebrush based on forage response data from a sagebrush control experiment in Carbon County, Wyo. Forage response data are based on the difference in herbage between treated and untreated experimental units from sites ranging in initial sagebrush canopy cover from 4 to 40%. Breakeven returns per AUM were estimated for each sagebrush canopy cover level assuming 2,4-D (2,4-dichlorophenoxyacetic acid) or burning (for 28 to 40% canopy cover) as a control method with lives of control at 15, 20, and 25 years. These breakeven returns were compared to a net lease rate of $6.13/AUM. Results indicate the economic threshold abundance of sagebrush is 12% assuming, 2,4-D as the control method and a control longevity of 25 years, but the feasible sagebrush abundance increases as longevity of control decreases. If the longevity of the control only lasts 20 years, the sagebrush abundance must be at least 20% before treating sagebrush becomes economically feasible. If the longevity of control is only 15 years, sagebrush abundance must be at least 24% canopy cover before treatment is economically viable. Given estimates of the cost of burning are almost half that of spraying with 2,4-D, all the scenarios which had enough biomass to sustain a burn (28% to 40%) indicated sagebrush control by fire was economically viable.