1a. Objectives (from AD-416)
1) Synthesize research to develop a guide to managing medusahead in sagebrush steppe plant communities in the Intermountain West. Special attention will be on recent research that provides practical and sustainable management recommendations. 2) Determine what species and/or combinations of species resist medusahead re-invasion. 3) Determine if native plants can resist medusahead re-invasion as successfully as introduced plants. 4) Identify the mechanisms (nutrient availability, soil water, etc) that promote plant community resistance to medusahead re-invasion.
1b. Approach (from AD-416)
The first objective will be accomplished by synthesizing recent research on the prevention, revegetation, and control of medusahead infestations in sagebrush steppe plant communities in the Intermountain West. This will include searching literature databases such as the Web of Science and specific journals including, but not limited to Invasive Plant Science and Management, Rangeland Ecology and Management, Weed Science, Restoration Ecology, and Weed Technology for articles pertaining to the management of medusahead. We will also include information from several of our research projects regarding the management of medusahead in sagebrush steppe plant communities that will be completed and published by the third year of this proposed project. To accomplish the next two objectives, we will establish five different plant communities in medusahead infested rangelands after control of medusahead with herbicides. The treatments will be: 1) crested wheatgrass, 2) forage kochia, 3) crested wheatgrass and forage kochia, 4) bluebunch wheatgrass and Wyoming big sagebrush, 5) crested wheatgrass and sagebrush and 5) control. Each treatment will be applied three times at two different sites for a total of six replications. Exclosures (6ft tall, 35 X 75 m) will be erected around the two sites to prevent herbivores from disturbing the treatments. Vegetation cover and density will be measured for the next three years to determine the short-term success. The treatments will continue to be measured every other year for the next 10 years to determine the long-term success of the plant communities. To determine the mechanisms that promote plant community resistance to medusahead invasion, four additional replicates of each treatment will established. Soil nutrient availability, soil water content, and site availability will be measured to determine how resource availability varies between plant communities that are resistant medusahead re-invasion and those that are not. Soil nutrients and water content will be measured throughout the growing season.
3. Progress Report
ARS scientists in Burns, OR synthesized existing literature to develop an interim medusahead management guide for the Intermountain West. The management guide detailed prevention, control, and revegetation strategies to manage medusahead. This interim management guide was provided to the NRCS and will be updated in 2013. We also treated medusahead infestations to prepare them for different revegetation plant mixes. We also built exclosures around the study sites to protect them. These treated plots will be seeded in the fall of 2011.