Location: Great Basin Rangelands Research
2022 Annual Report
Objectives
The long-term objective of the Great Basin Rangelands Research Unit (GBRRU) project plan is to facilitate sustainability of ecosystem goods and services provided by arid rangelands with a focus on production of forage for domestic grazing animals, conservation and restoration of these rangelands, and maintaining or enhancing ecosystem processes that facilitate desired plant communities. This will be approached by 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 management practices. The project will integrate basic research on Great Basin rangelands with new tools, plant materials, and technologies to reduce the spread of invasive and expanding plant populations and assess effectiveness of management practices. Specifically, during the next five years we will focus on the following objectives.
Objective 1: Develop tools and strategies for maintaining and enhancing the sustainability of arid rangeland ecosystems based on an improved understanding of soil properties, plant-soil relationships, and alternative management practices. (NP215 1A, 3B, 4A)
Subobjective 1A: Quantify salt mobility and transport as a function of rainfall return period on saline rangeland soils, and parameterize the Rangeland Hydrology and Erosion Model (RHEM) for estimating runoff, sediment yield and salt transport. (Weltz)
Subobjective 1B: Quantify vulnerabilities to soil erosion on non-federal rangelands as part of a national assessment in collaboration with NRCS. (Weltz, Newingham)
Subobjective 1C: Investigate effects of post-expansion piñon and juniper tree control and exclusionary fencing on components of the water budget and recovery of sagebrush steppe and meadow habitats and assess weather variability and impacts on plant phenology. (Snyder)
Subobjective 1D: Apply bioinformatic analyses to newly developed single-nucleotide polymorphism (SNP) markers to determine whether outcrossing and heterosis in cheatgrass may facilitate invasion of new environments in Great Basin ecosystems. (Longland)
Objective 2: Evaluate rangeland community productivity, responses to disturbance, and identify appropriate rehabilitation practices. (NP215 1A, 3B, 4A)
Subobjective 2A: Assess effects of post-fire grazing on burned rangelands. (Newingham)
Subobjective 2B: Quantify effects of arthropod seed predators in reducing seed viability of western and Utah juniper as a potential pre-establishment control strategy. (Longland)
Subobjective 2C: Develop management strategies providing guidelines and tools to stakeholders for enhancing native grass productivity on Great Basin rangelands using diversionary seeding. (Longland)
Approach
Subobjective 1A, Hypothesis: Runoff, sediment yield, and salt transport processes will increase as a non-linear function of rainfall return period through rill processes being initiated. Rainfall simulations will be conducted to quantify salt mobility and transport as a function of rainfall return period on saline rangeland soils and to parameterize the Rangeland Hydrology and Erosion Model.
Subobjective 1B, Research Goal: Quantify rangeland vulnerability to soil erosion. Unit scientists and a team from the National Agricultural Library will develop the Agricultural Runoff Erosion and Salinity database. They will also expand the current understanding of wind erosion processes in the Great Basin by establishing a new post-fire National Wind Erosion Research Network site in eastern Nevada. These research activities will allow users to quantify vulnerabilities to soil erosion on rangelands.
Subobjective 1C, Hypothesis: Mechanical tree control treatments for piñon and juniper will reduce precipitation interception and tree transpiration losses and result in increased soil moisture, which will increase the presence and diversity of the desired understory vegetation. Ecological and hydrological instrumentation will be used at a field station in central Nevada to: (1) investigate effects of post-expansion piñon and juniper tree control and exclusionary fencing on components of the water budget and recovery of natural habitats, and (2) assess weather variability and impacts on plant phenology.
Subobjective 1D, Hypothesis: Occasional outcrossing facilitates expansion of cheatgrass across the intermountain west by selecting for new genotypes adapted to drier sites and more alkaline soils. Bioinformatic analyses will be applied to newly developed single-nucleotide polymorphism (SNP) markers in order to determine whether outcrossing and heterosis in cheatgrass may facilitate invasion of new environments in Great Basin ecosystems.
Subobjective 2A, Hypothesis: Delaying defoliation at least two years post-fire will ensure adequate perennial grass establishment. Defoliation experiments with native perennial grass species will be conducted to assess effects of post-fire grazing on burned rangelands.
Subobjective 2B, Hypothesis: Arthropods that feed on juniper seeds vary systematically in their quantitative impacts in rendering seeds inviable. Systematic sampling of juniper berries from several field sites and laboratory dissection of the berries to identify associated arthropods will be used to quantify effects of arthropod seed predators in reducing seed viability of western and Utah juniper as a potential pre-establishment control strategy.
Subobjective 2C, Hypothesis: Manipulating the behavior of granivorous rodents through the addition of preferred diversionary seeds to field plots enhances seedling recruitment of Indian ricegrass. Using commonly available commercial seeds, seed augmentation experiments intended to manipulate the behavior of seed-caching rodents (i.e., “diversionary seeding”) will be conducted to develop management strategies for enhancing native grass productivity on Great Basin rangelands.
Progress Report
Progress was made on Sub-objective 1B specifically, Research Goal 1B.2, “Expand the current understanding of wind erosion processes in the Great Basin by establishing a new post-fire National Wind Erosion Research Network (NWERN) site in eastern Nevada.” Fire not only affects water erosion and associated watershed processes, but also affects wind erosion due to exposed soil for several months after fire. However, little information exists about the effects of fire on wind erosion. In collaboration with the Bureau of Land Management (BLM), we installed two wind erosion sites (Twin Valley and Red Hills) associated with the National Wind, Erosion, Research Network (NWERN) in 2019, which are located at the 2018 Martin Fire. Measurements include temperature, relative humidity, precipitation, wind speed and direction, saltation, dust flux, soil deposition, soil particle size distribution, soil surface roughness, aggregate size distribution, biological soil crust, and vegetation. Dust flux samples were collected monthly unless sites were not accessible. Vegetation and soil surface characteristics, as well as deposition samples, were collected three times in the past year. Data have been submitted to the NWERN database. Research collaborations across the NWERN associated with Long-Term Agroecosystem Research (LTAR) have been facilitated through monthly meetings. A new post-fire erosion research team is being developed along with other ARS locations.
Weed challenges in the Great Basin are not limited to exotic or annual species. Since the 1850s, native conifers (juniper and pinyon pine) have been infilling existing woodlands and expanding into sagebrush steppe. This reduces herbaceous forage, alters wildlife habitat, accelerates surface runoff and soil erosion, increases woody fuel loads, and increases risk of catastrophic wildfires, with significant loss of ecosystem services. Of great concern to land managers in arid environments is the amount of water used available and used by various plant species. Ecohydrological data collection in the Porter Canyon Experimental Watershed (PCEW) in the Desatoya Mountain Range is now in its twelfth year, with the goal to develop tools and strategies for arid rangeland ecosystems based on an integrated understanding of plant and soil relationships.
Progress has also been made on research that addresses Sub-objective 1C. The BLM is continuing to remove trees in the PCEW and we continue to collect data on soil moisture, soil temperature, plant phenology, spring flow, groundwater levels, streamflow, and plant community composition. A study was completed and published on the amount of rainfall that is intercepted by mountain big sagebrush at various stand densities. This new study complements an earlier study that quantified the amount of rainfall intercepted by pinyon and juniper trees.
Once pinyon and juniper are removed, mountain mahogany trees previously in the understory, become more dominant on the landscape. We have selected two sites where we will install sap flow probes on mountain mahogany to determine the water requirements of this species with and without an overstory of pinyon and juniper. One site has been instrumented with sap flow probes this field season. These new sites will provide an additional component of understanding the water budget in Great Basin plant communities.
Riparian and ground-water dependent ecosystems found in the Great Basin of North America are heavily utilized by livestock and wildlife throughout the year. Due to this constant pressure, grazing can be a major influence on many riparian resources. It is important for land managers to understand how intensity and timing of grazing affect the temporal availability of these commodities (i.e., biodiversity, water filtration, forage, habitat). Upper elevation groundwater-dependent meadows in Haypress have been fully instrumented for four full growing seasons. Four years of a grazing experiment have now been completed with information on soil moisture and plant community responses. Baseline data on plant composition and phenology with no grazing exclusion (both cattle and feral horses) were collected during the growing season of 2019. Exclusionary fencing was built in fall of 2019, and data on plant composition and phenology was collected during the growing seasons of 2020, 2021, and 2022 on three replicated treatments: managed grazing, no grazing, and uncontrolled grazing. A manuscript was completed and published on the first two years of data. This research found strong agreement between on-the-ground measurements of plant phenological stage, phenology determined with images from near-surface digital cameras (phenocams), and Landsat satellite-based indices of plant vigor such as Normalized Difference Vegetation Index (NDVI). A new manuscript is being prepared regarding the abundance and composition of insects in plots with different grazing regimes, and these metrics are being compared with phenology metrics of plant communities.
Native perennial bunchgrasses are often seeded, and domestic livestock grazing is often delayed by two growing seasons after wildfire in the Great Basin. Seeding failures often occur due to unsuitable abiotic conditions or inappropriate post-fire management.
Progress was made on Sub-objective 2A, in which ARS researchers in Reno, Nevada, continued to monitor an experiment examining how neighboring plant communities and timing of post-fire defoliation affect post-fire seeding treatments in Artemisia tridentata ssp. wyomingensis communities in northwest Nevada and southeast Oregon. Plant removal treatments varied the relative density of adult and seedling perennial bunchgrasses, while spring and fall defoliation treatments simulated livestock grazing. We recorded within-season timing of senescence, leaf and inflorescence production, and stem length, as well as across-season bunchgrass density, foliar cover, and seedling survival. Preliminary analyses showed that fall and spring defoliation within seedling removal hastened senescence following defoliation, while spring defoliation decreased leaf production, stem length, and inflorescence production. Adult and seedling removal both decreased plant density and foliar cover in the first year after fire. Our results will inform managers on whether post-fire plant community structure affects restoration efficacy, and whether spring and fall defoliation treatments differ in their effects on seedling perennial bunchgrasses.
Under Sub-objective 2C, progress was made in enhancing grass productivity on Great Basin rangelands. The accidental introduction and subsequent invasion of the annual grass, cheatgrass, has increased the frequency of wildfires. Millions of dollars are spent annually fighting these fires and millions more are spent trying to restore burned habitats. Progress was made on Sub-objective 2C and subordinate project, agreement number 58-2060-9-001, for developing guidelines and tools for enhancing native grass productivity on Great Basin rangelands. Pre-emergent herbicides are being tested to control cheatgrass densities and subsequent competition with seeded species to improve restoration success and decrease cheatgrass densities and associated fuels. The use of the pre-emergent herbicide, Imazapic, reduced cheatgrass densities by 98.6% which resulted in successful recruitment of seeded perennial grass species. Judicious use of pre-emergent herbicides can decrease cheatgrass densities, and if coupled with active seeding efforts can increase desirable perennial grass species for wildlife habitat and livestock forage.
Additional progress in support of Sub-objective 2C included treating an old decadent shrub community with the mechanical implement, the Lawson Aerator, and seeding it with two native and two introduced perennial grasses. Residual Great Basin wildrye plants and salt grass were released from the site and complemented with seedling recruitment of seeded species Great Basin wildrye, tall, and Intermediate wheatgrass. Mechanical treatment to reduce decadent shrub competition followed by seeding treatments increased perennial grass densities by 675% and forage production by more than 1,000%. Increases in sustainable grazing resources allows resource managers and landowners more flexibility in their grazing management and livestock operation that not only benefits grazing pastures, but also wildlife habitat. Preliminary results were presented at an international meeting and a stakeholder field tour.
Accomplishments
Review Publications
Newingham, B.A., Kachergis, E., Ganguli, A.C., Foster, B., Price, L., McCord, S.E. 2021. Lessons given and learned from rangeland monitoring courses. Rangelands. 44(1):29-38. https://doi.org/10.1016/j.rala.2021.08.003.
Richardson, W., Stringham, T., Lieurance, W., Snyder, K.A. 2021. Changes in meadow phenology in response to grazing management at multiple scales of measurement. Remote Sensing. 13(20). Article 4028. https://doi.org/10.3390/rs13204028.
Snyder, D.K., Stringham, T.K., Snyder, K.A. 2022. Rainfall interception by mountain big sagebrush (Artemisia tridentata spp. vaseyana): Dryland shrub canopy cover affects net precipitation. Hydrological Processes. 36(1). Article e14441. https://doi.org/10.1002/hyp.14441.
Hammond, D.H., Strand, E.K., Morgan, P., Hudak, A.T., Newingham, B.A. 2021. Environmental influences on density and height growth of natural ponderosa pine regeneration following wildfires. Fire. 4(4). Article 80. https://doi.org/10.3390/fire4040080.
Haddad, M., Strohmeier, S.M., Nouwakpo, S.K., Rimawi, O., Weltz, M.A., Sterk, G. 2022. Rangeland restoration in Jordan: Restoring vegetation cover by water harvesting measures. International Soil and Water Conservation Research. https://doi.org/10.1016/j.iswcr.2022.03.001.
Clements, D.D., Harmon, D.N., Blank, R.R. 2022. Seed mix performance and cheatgrass suppression on arid rangelands. Rangelands. 44(2):129-135. https://doi.org/10.1016/j.rala.2022.02.003.
Pyke, D.A., Schaff, S.C., Chambers, J.C., Schupp, E.W., Newingham, B.A., Gray, M.L., Ellsworth, L.M. 2022. Ten-year ecological responses to fuel treatments within semiarid Wyoming big sagebrush ecosystems. Ecosphere. 13(7). Article e4176. https://doi.org/10.1002/ecs2.4176.
