Location: Great Basin Rangelands Research
Project Number: 5370-13610-001-00
Start Date: Jun 03, 2013
End Date: Jun 02, 2018
Objective 1.1: Determine how the reproductive ecology of invasive annuals affects the structure and function of selected Great Basin ecosystems. Hypotheses: Occasional outcrossing facilitates expansion of cheatgrass across the intermountain west by selecting for new genotypes adapted to drier and more alkaline sites. IonTorrent® platform will be utilized to identify new single-nucleotide polymorphisms (SNPs) in cheatgrass to document if outcrossing is occuring. Objective 1.2: Determine mechanisms underlying the expansion of native western juniper woodlands. Hypothesis: Quantify rodent preferences to either juniper berries hand-collected or passed through the gut of a Robin and determine percent germination and seedling establishment between treatments. Objective 1.3: Determine how cheatgrass invasion and climate change interact with one another to affect the structure and long-term persistence of sagebrush. Hypothesis: Climate change and competition from cheatgrass will independently and interactively reduce the persistence of sagebrush populations. Field studieswill examine sagebrush demography across its geographic range. Growth chamber experiment will study interactions of atmospheric CO2 levels, soil moisture, and plant competition on sagebrush germination, seedling survival, and growth parameters. Objective 2: Assess and quantify interactions between annual grasses and fire on watershed processes and ecosystem services. Hypothesis: Conversion of Wyoming sagebrush community to cheatgrass, as a result of wildfire, will negatively alter runoff and erosion. Rainfall simulation will be used to quantify soil erosion in intact sagebrush and ecosystems converted to annual grass dominance and predict soil erosion with the Rangeland Hydrology and Erosion Model (RHEM). Ojective 3.1: Mechanistically understand how intact perennial grass communities resist invasion by cheatgrass. Hypothesis: Healthy, robust, and intact perennial grass communities facilitate resistance to invasion by cheatgrass. Growth of cheatgrass will be contrasted in soil occupied by established perennial grasses and in unoccupied soil in greenhouse and field studies. Objective 3.2: Provide management guidelines and transferable technologies to our stakeholders for establishing and enhancing Great Basin ecosystems. Hypotheses: Combined application of appropriate soil-active herbicides and optimal plant materials will enhance revegetation/restoration success on cheatgrass-infested rangelands. Objective 4: Enhance ARS natural resource models (e.g. RHEM) for assessing hydrology and erosion responses associated with management of disturbed vegetation states and transitions occurring on sagebrush-steppe ecological sites. Hypothesis: Runoff and soil erosion will increase when either pinyon/juniper or annual grasses invade sagebrush-steppe ecosystems. An instrumented watershed, Porter Canyon in central Nevada, will be used to evaluate the impact of cheatgrass invasion and pinyon/juniper woodlands on surface runoff, soil loss and sediment yield. Data will be used to evaluate model performance and measure utility of model to assess conservation practices.