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Research Project: Ecological Interactions in Integrated and Biologically-Based Management of Invasive Plant Species in Western Rangelands

Location: Great Basin Rangelands Research

Project Number: 2060-22000-023-00-D
Project Type: In-House Appropriated

Start Date: Dec 28, 2010
End Date: Oct 14, 2015

Objective 1. Conduct foreign exploration and biological evaluation for biological control agents of weeds of western rangelands such as the annual grass medusahead rye and perennial pepperweed. Sub-objective 1.1: Conduct foreign exploration for natural enemies of medusahead rye and perennial pepperweed. Sub-objective 1.2: Conduct host-specificity testing and impact evaluation to assess biological control candidates of target weeds for risk to non-target organisms. Objective 2. Understand the ecology, biology and genetic variation of invasive weeds such as saltcedar, perennial pepperweed, and medusahead rye, and their natural enemies. Sub-objective 2.1: Conduct ecological studies of seed predators and other natural enemies of medusahead rye in the native and invaded ranges. Sub-objective 2.2: Characterize genetic variation of Lepidium latifolium (perennial pepperweed) in its native and invaded ranges. Objective 3. Determine the effects of integrated weed suppression (particularly saltcedar) and woody plant removal (pinyon and juniper) on ecosystem processes such as water and carbon cycling, and on long-term successional processes (including plants and wildlife), insect impacts on invasion, and restoration processes to facilitate science-based rehabilitation and restoration of lands invaded by these weeds. Sub-objective 3.1: Long-term monitoring of the effects of Diorhabda carinulata (northern Tamarisk beetle) on ecosystem functions, tree mortality and wildlife populations in areas affected by saltcedar biological control. Sub-objective 3.2: Determine guidelines for secondary control methods and restoration planning. Sub-objective 3.3: Determine the effects of two pinyon and juniper removal treatments on the hydrologic budget, particularly soil moisture, as well as understory composition. Objective 4. Develop restoration methodologies to prevent the invasion of annual grasses (such as cheatgrass, medusahead rye, and/or red brome) following destructive events (such as fire) in rangeland ecosystems.

Over the next five years we will conduct research to develop appropriate strategies to control exotic weeds and encroaching native species in western rangelands and riparian areas. Control measures will focus on using classical biological control to find insect enemies of exotic weeds, as well as other control measures, such as mechanical treatments. Genetic analyses of exotic weed species will determine the diversity of populations in the invaded range and identify similar populations in the native range to improve our ability to select effective control agents. There is little research on the ecosystem impacts of control measures; we will determine the impacts of control measures on ecosystem functions including carbon and water cycling, plant community composition and small animal diversity. We will also conduct research to determine appropriate restoration strategies for these ecosystems, by testing planting techniques and novel seed mixtures. These investigations will include basic and applied studies using hypothesis-driven experiments conducted in the laboratory, greenhouse, and field.