Sage grouse and trees in the sagebrush simply don’t mix. Trees are perch sites for raptors that prey on grouse and the birds stay clear of them. However, since the late 1800’s, pinyon pine and juniper (PJ) has subtly been invading vast acreages of rangeland that were once dominated by sagebrush, grasses, and forbs. Although PJ are native plants, fire suppression and other factors have allowed these trees to expand to sites they never occupied historically. As PJ expands its range, it gradually results in a number of resource problems, such as reduced forage production, increased soil erosion, altered wildlife habitat, and reduced stream and spring flows.
Besides affecting a rancher’s bottom line by reducing forage production, PJ invasion is severely impacting rangeland wildlife like mule deer and sage-grouse. These wildlife species depend primarily upon the shrubs, grasses, and wildflowers that are lost when trees move in. Sage-grouse, in particular, are sensitive to PJ invasion and their range has shrunk dramatically due to the loss of habitat to trees.
Once PJ’s become dense and mature, the understory grasses and shrubs die out and it becomes much more difficult and expensive to restore forage production and reverse other resource problems. However, areas that are still in the early phases of PJ invasion often retain a large component of grasses and shrubs. This provides an opportunity to reverse resource degradation relatively inexpensively through the removal of young trees. Removing encroached PJ functionally restores otherwise suitable habitat for 40 to 50 years.