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ARS Home » Pacific West Area » Reno, Nevada » Great Basin Rangelands Research » Research » Research Project #445796

Research Project: System-based Management and Rehabilitation of Rangelands

Location: Great Basin Rangelands Research

Project Number: 2060-21500-001-000-D
Project Type: In-House Appropriated

Start Date: Feb 22, 2024
End Date: Feb 21, 2029

The long-term objective of the Great Basin Rangelands Research Unit (GBRRU) project plan is the sustainability of arid rangelands with a focus on addressing critical research needs affecting arid and semi-arid rangelands, including: (1) investigating the ecology and control of invasive weeds, (2) rehabilitating degraded rangelands, (3) maintaining and enhancing productive rangelands, and (4) quantifying impacts of disturbance and management practices. The project will integrate basic research on rangelands with new tools, plant materials, and technologies to reduce the spread of invasive and expanding plant populations and assess effectiveness of management practices. Objective 1: Improve understanding of how disturbance and management impact water and soil resources to maintain plant productivity and ecosystem function in arid rangeland systems. Sub-objective 1.A: Quantify the long-term effects of post-expansion tree controls on components of the water budget in the Porter Canyon Experimental Watershed. (Snyder and Vacant Research Hydrologist) Sub-objective 1.B: Quantify soil loss and resulting effects on plant communities in rangelands. (Newingham, Vacant Soil Scientist, and Vacant Research Hydrologist) Objective 2: Evaluate the effectiveness of fuel treatments, rehabilitation, and other management strategies on plant community development and ecosystem function. Sub-objective 2.A: Quantify community phenology and carbon dioxide and water fluxes of meadows with variable weather and different grazing regimes. (Snyder) Sub-objective 2.B: Evaluate the long-term effects of fuel treatments on sagebrush shrublands and pinyon-juniper woodlands. (Newingham, Vacant Soil Scientist, and Vacant Research Hydrologist) Sub-objective 2.C: Develop management strategies and provide tools for enhancing perennial grass productivity on Great Basin rangelands. (Clements and Vacant Soil Scientist)

The Porter Canyon Experimental Watershed will determine if large-scale mechanical control of trees changes components of the water budget. Evapotranspiration (ET) is the largest component of the water budget in drylands yet is generally measured as one term. This research will advance the scientific understanding of the water budget by disentangling components of ET and independently measuring transpiration of dominant woody species and soil moisture in treated and untreated areas. Sub-objective 1.A, Hypothesis: Mechanical tree control treatments for pinyon and juniper will reduce precipitation interception and tree transpiration losses and result in increased soil moisture and provide an increased water supply for mountain mahogany. Wildfire remains one of the most prominent disturbances impacting rangelands, leaving barren soils susceptible to water and wind erosion until vegetation recovery occurs or mitigation by erosion control techniques. Although research has been conducted on post-fire water erosion, there is a paucity of post-fire wind erosion research. Subobjective 1.B, Research Goal: Quantify soil loss due to wind and/or water erosion on rangelands; evaluate existing erosion equipment and methods for improvement. Eddy covariance towers are an established methodology to compare the effects of management strategies on the fluxes of carbon dioxide and water lost though soil evaporation and plant transpiration. Phenocams have been established as a methodology that is suitable for quantifying plant phenology. We will select a grazed and an ungrazed meadow to instrument with eddy covariance towers and phenocams. Sub-objective 2.A, Research Goal: Determine the carbon sequestration potential and evapotranspiration losses and how this relates to plant phenology in a grazed and ungrazed meadow. We will use field sites that have burned in the Sagebrush Steppe Treatment Evaluation Project network, a long-term study replicated in 20 locations across the Intermountain West to evaluate fuel treatment effectiveness in the sagebrush ecosystem. Sub-objective 2.B, Hypothesis: Fuel treatment type will influence post-wildfire plant community recovery and fuel loads. Cheatgrass is the most dominant and successful invasive weed species in the Great Basin. Seeding to rehabilitate cheatgrass-infested rangelands is widely used in the Great Basin. Resource managers lack the necessary information of effective seeding rates and species selection of both drill and broadcast seeding methods. We are evaluating standardized perennial grass seeding rates compared to lower and higher seeding rates with commonly used drill and broadcast seeding methods to determine the most cost-effective means of increasing perennial grass establishment and reducing cheatgrass. Sub-objective 2.C.1, Hypothesis: High seeding rates will have significantly more grass seedlings per unit area established compared to low seeding rates when planted with a no-till drill. Sub-objective 2.C.2, Hypothesis: High seeding rates will have significantly more grass seedlings per unit area established compared to low seeding rates when using broadcast seeding as a seeding method.