The pinyon-juniper experiments were among the first conducted in the Beaver Creek area. Prior to these studies, many woodland managers thought pinyon-juniper removal would improve both streamflow and forage production. Large areas throughout the Southwest had been cleared expecting these benefits. However, results at Beaver Creek show that substantial forage increases are possible, but that changes in water yield are not likely to be significant. A paired watershed approach was used to determine water yield responses.

Treatments—Three techniques were used to remove pinyon and juniper trees from Watersheds 1, 3, and 6—uprooting, herbicide spraying, and cutting, respectively. Herbicide spraying on Watershed 3 was the only treament to yield a significant streamflow increase. However, the government carefully controls the use of herbicides for environmental reasons, limiting the general use of this technique. Mechanical removal, such as uprooting or cutting, is the primary means for converting pinyon-juniper woodlands to other types of vegetation.

According to Hibbert (1979), little opportunity exists to reduce transpiration where precipitation is less than about 18 inches (460 mm) and is exceeded by potential evapotranspiration (warm, dry portions), because precipitation does not penetrate far into the soil, and one vegetation type is about as efficient as another in using the available water. Most pinyon-juniper woodlands receive 18 inches or less presipitrtion annually.