Research Project: Invasive Species Assessment and Control to Enhance Sustainability of Great Basin Rangelands

Location: Great Basin Rangelands Research

Project Number: 2060-13610-002-000-D
Project Type: In-House Appropriated

Start Date: Jun 3, 2018
End Date: Mar 24, 2019

Objective:
The Great Basin is the largest North American desert covering more than 50 million hectares. Major vegetation types in the Great Basin include: salt desert shadscale/greasewood, sagebrush/bunchgrass and mountain shrublands, pinyon/juniper woodlands, subalpine forests, and alpine tundra. The region has extremely variable climate both spatially and temporally and a complex mixture of public and private land ownership. Ranching, mining, and recreation form the basis of rural economies. Over 20% of Great Basin ecosystems have been significantly altered by invasive plants. This land conversion has resulted in dramatic reductions in forage availability, wildlife habitat, and biodiversity, has increased wildfire frequency and intensity, and altered the hydrologic cycle. Critical research needs addressed in this project are: (1) ecology and control of invasive weeds, (2) rehabilitation of degraded rangelands, (3) maintaining/enhancing healthy rangelands, and (4) quantifying the impact of management practices. Objective 1. Assess and quantify ecological conditions and biotic processes that maintain healthy rangelands, improve forage production, and enhance recovery of degraded sagebrush, and pinyon/juniper woodlands under uncertain climatic conditions in the Great Basin. • Sub-objective 1.1: Expand the ‘genetic toolbox’ to allow us to determine how the reproductive ecology of invasive annuals affects the structure and function of selected Great Basin ecosystems. • Sub-objective 1.2: Determine mechanisms underlying the expansion of native western juniper (Juniperus occidentalis) woodlands. Objective 2. Assess and quantify interactions between annual grasses and fire on watershed processes and ecosystem services under uncertain climatic conditions. Objective 3. Develop and transfer innovative management approaches and technology for conserving and rehabilitating sagebrush, pinyon/juniper woodlands, and salt desert shrublands to meet natural resource and agricultural production goals. • Sub-objective 3.1: Mechanistically understand how intact perennial grass communities resist invasion by annual grasses, especially cheatgrass. • Sub-objective 3.2: Provide management guidelines and transferable technologies to our stakeholders for establishing and enhancing native and introduced grasses, forbs, and shrubs in Great Basin ecosystems. Objective 4. Develop decision support tools for USDA to assess impact of type, location and number of management practices required to meet conservation and agricultural production goals nationwide. • Sub-objective 4.1: Enhance RHEM, KINEROS2, APEX, and SWAT models for assessing hydrology and erosion responses associated with management of disturbed vegetation states and transitions occurring on sagebrush-steppe ecological sites. • Sub-objective 4.2: As part of a national assessment, quantify soil loss on western rangelands.

Approach:
Objective 1.1: Determine how the reproductive ecology of invasive annuals affects the structure and function of selected Great Basin ecosystems. Hypothesis: 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 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). Objective 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. Hypothesis: 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.