Rangeland Conservation Analysis # 2 Controlling Cheatgrass and Woody Species Invasion in the Great Basin

The Issue Invasive species, widely distributed across the western United States, pose critical conservation challenges on both non-Federal and Federal rangelands. Two of the biggest threats to ecosystem stability and integrity in the Great Basin (most of Nevada, a large part of Utah, and smaller sections of Oregon, Idaho, and California) are invasive annual grasses, particularly cheatgrass and medusahead, and invasive woody plants, particularly juniper species and pin-yon pine. Invasions of both types of plants can lead to soil erosion problems, increase the likelihood of damaging and dangerous wildfires, reduce forage availability, and significantly alter wildlife habitat. Frequent fires degrade soil health by destroying litter which would otherwise naturally decompose and contribute nutrients and carbon back to the soil. Soil health is also degraded by increased rates of wind and water erosion following fire. Although soil may recover from the direct impacts of fire, persistent occupation by inva-sive species can have lasting consequences for soil health and rangeland ecosystems (Allen et al. 2011). Altered fire regimes associated with settlement of the West and active management of lands are intertwined with the expansion of invasive plant species. Fire suppression and historical grazing patterns have contributed to increased density of pinyon-juniper stands. As a result of higher fuel loads, when fires do occur they are more severe, opening the landscape to introduction of alternate species for longer periods of time (Miller et al. 2008; Keane et al. 2002; Schoennagel et al. 2004). The number of fires and total area burned increased from 1980 through 2007 for most of the sagebrush steppe biome, including the Sage Grouse Conservation Area. Average fire size has increased for the southern Great Basin (Miller et al. 2011), and fire intervals have decreased to as little as 5 years in the Snake River plains area of Idaho (Whisenant 1990). Commercial cattle production is the predominant agricultural use of Great Basin rangelands, but invasive species and wildfires affect many stakeholders including home and business owners; birders, hunters, and fishers; and conservation and land management agencies. Across the West, loss of human life and extensive damage to natural resources, property, and city infrastructures have been documented in relation to intense rainfall events following wildfires in areas that have not had sufficient time to revegetate (Moody and Martin 2001; Pierson et al. 2002; Cannon et al. 2011). Mitigating these potential post-fire impacts is of particular concern along the ever-expanding wildland-urban interface …