Research Project: Management and Restoration of Rangeland Ecosystems

Location: Great Basin Rangelands Research

2023 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
This report documents progress in Fiscal Year (FY) 2023 for project 2060-13610-003-000D, titled, “Management and Restoration of Rangeland Ecosystems”. In support of Sub-objective 1B/Research Goal 1B.2, ARS researchers in Reno, Nevada, continued observations on post-fire wind erosion after wildfire. Wildfire 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), ARS researchers installed two wind erosion sites (Twin Valley and Red Hills) associated with the National Wind Erosion Network (NWERN) in 2019, which are located on 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, which was true for most of the winter. Vegetation and soil surface characteristics, as well as deposition samples, were collected three times in the past year. Additional data was collected to evaluate grazing effects on post-fire wind erosion at the Red Hills site, as well as examining microbial communities from the NWERN. Data has been submitted to the NWERN database; the Aeolian Erosion Model (AERO) was developed and refined. Research collaborations across the NWERN associated with Long-term Agroecosystem Research (LTAR) have been facilitated through monthly meetings and analyses have included exampling sample sizes appropriate to measure wind erosion. A new post-fire erosion research team is being developed along with Tucson, Arizona. In support of Sub-objectives 1C1 and 1C2, ARS researchers continued to collect data on snow depth, soil moisture, soil temperature, plant phenology, spring flow, groundwater levels, streamflow, and plant community composition. Ecohydrological data collection in the Porter Canyon Experimental Watershed (PCEW) in the Desatoya Mountain Range is now in its thirteenth year. Since the 1850s, native conifers (juniper and pinyon pine) have been infilling existing woodlands and expanding into sagebrush steppe The goal of PCEW is to develop tools and strategies for arid rangeland ecosystems based on an integrated understanding of the effects of woody plant encroachment by pinyon and juniper on the sagebrush steppe, and efforts to reduce woody species through tree removal treatments. A manuscript was submitted on the use of stemflow water generated during rainfall events by the encroaching species pinyon and juniper. It has been postulated that stemflow, precipitation that flows from plant crowns down along branches and stems to soils, benefits plants that generate it because it increases plant-available soil water near the base of the plant; however, little direct evidence supports this postulation. For example, encroaching pinyon and juniper trees are known from previous research at PCEW to intercept on average 43% of precipitation and of that 4% becomes stemflow; if this stemflow is taken up by trees it may provide a benefit to trees with large canopies at the expense of shrubs and grasses. This manuscript used a novel stable isotopic approach to apply isotopically labelled water to trees and track the fate of this water through the experimental trees in two years. The two years encompassed a drier than average, and a wetter than average year. Both species took up stemflow, with label signals peaking and receding over two to four days. Despite this uptake, no alleviation of water stress was detected in the drier year. The stemflow uptake resulted in some water stress alleviation in the wetter year, specifically for pinyons, which took up water from deeper in the soil profile than did junipers. While a physiological benefit was not detected, the uptake of stemflow by encroaching tree species makes this water unavailable to shrubs and grasses. In support of Sub-objective 1C3, ARS researchers continued to collect and analyze data from phenological cameras in high elevation meadows. 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 with weather stations, soil moisture probes, permanent automated plant phenology cameras, and insect pit-fall traps. 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 2019 growing season. 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 submitted 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 derived from the automated cameras. A new manuscript is being prepared in which we are using data from the U.S. Geological Survey on the locations of the threatened greater sage-grouse in conjunction with our data to understand how various environmental factors affect grouse utilization of upland meadows during spring and summer months. These factors will include meadow composition, size, boundary effects of various cover types, horse and cattle use, and plant community phenology indices calculated from field-based cameras. In support of Sub-objective 2A, ARS researchers in Reno, Nevada, evaluated perennial bunchgrass responses to defoliation after wildfire. Native perennial bunchgrasses are often seeded and domestic livestock grazing is often delayed for two growing-seasons after wildfire in the Great Basin, United States. Seeding failures often occur due to unsuitable abiotic conditions or inappropriate post-fire management. Researchers monitored 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 for five years. Plant removal treatments varied the relative density of adult and seedling perennial bunchgrasses, while spring and fall defoliation treatments simulated livestock grazing. ARS researchers 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. Three years of data have been added to the dataset and analyses are being updated and finalized. Their 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. Although Sub-objective 2C was originally assigned to the retired Research Ecologist, progress has been made on the use of seed mixes in rehabilitation efforts, minus the focus on granivorous rodents. Progress was made in support of Sub-objective 2C, with the testing of perennial grass, shrub and forb seed mixes following a catastrophic 176,000 hectare (ha) wildfire to evaluate the effectiveness of post-fire management strategies. Seed mixes included native and introduced plant materials developed by ARS. Seeded habitats yielded a 4-fold increase in perennial grass, shrub and forb densities compared to unseeded habitats. The introduced seed mix established significantly more perennial grasses than the native seed mix, whereas the native seed mix established significantly more shrubs and forbs than the introduced seed mix. The importance of establishing perennial grasses plays a critical role in suppressing cheatgrass densities and fuel loads, while providing sustainable grazing resources and reducing wildfire threats to wildlife habitats. Preliminary data was presented at the International Society for Range Management Meeting and a stakeholder field tour. Additional progress in support of Sub-objective 2C included the mechanical treatment of decadent shrub communities with the Lawson Aerator to address stand decadence and improve herbaceous productivity. Following the mechanical application, the habitat was seeded using 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 from 1.2/meters squared (m²) to 8.1/ m² and forage production increased from 513 kg/ha to 5,554 kg/ha. Following the initial treatment of this habitat in 2020, the effects of reduced stand decadence increased forage productivity and continues to persist. Increases in sustainable grazing resources allows resource managers and landowners more flexibility in their grazing management and livestock operations that not only benefits grazing pastures, but also wildlife habitat. Preliminary results were presented at an international meeting and a stakeholder field tour.

Accomplishments
1. Lawson aerator increases herbaceous cover of grazing pastures. Sustainable grazing resources are often decreased due to shrub communities becoming old and decadent. Decreases in herbaceous perennial vegetation can decrease livestock producers’ flexibility in grazing pastures which can lead to over grazed rangelands and negatively affect sensitive wildlife species, such as the greater sage-grouse. ARS researchers in Reno, Nevada, are testing the use of a mechanical implement, the Lawson Aerator, to treat old, dense, and decadent shrub communities and increase herbaceous perennial vegetation and sustainable grazing resources. The use of the Lawson Aerator on 364 hectares of degraded shrub habitats in northern Nevada resulted in an increase of herbaceous perennial grass densities, from 1.2/m² to 8.1/m², as well as an increase in forage from 513 kg/ha to 5,554 kg/ha. The significant increase in forage also resulted in increased use and flexibility of this grazing pasture from less than four weeks to more than 14 weeks. Federal, state and private sector land managers have adopted this tool to further improve grazing pastures and wildlife habitat, such as Nevada Gold Mines purchasing a Lawson Aerator and recently treating 75 hectares within their land holdings.

2. New technology to examine the effects of chronic feral horse grazing and managed cattle grazing. In the Great Basin, overgrazing by feral horses is a persistent management problem especially in riparian areas, such as meadows. Feral horse populations have often exceeded the prescribed carrying capacity and this can negatively impact efforts by ranchers to manage their livestock for the desired range condition. These meadows are critical habitat for the at-risk species, the greater sage-grouse, and overgrazing by feral horses is a threat to the sustainability of these ecosystems. ARS researchers from Reno, Nevada, and Las Cruces, New Mexico, 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). Meadows with chronic feral horse grazing and three months of cattle grazing reduced gross primary production and greenness by 50% in comparison to meadows that had short-term managed grazing (two months by livestock only). The ability to detect differences in grazed systems with phenocams and freely available Landsat provides important technology for land managers.

Review Publications
Snyder, K.A., Richardson, W., Browning, D.M., Lieurance, W., Stringham, T.K. 2023. Plant phenology of high-elevation meadows: Assessing spectral responses of grazed meadows. Rangeland Ecology and Management. 87:69–82. https://doi.org/10.1016/j.rama.2022.12.001.
Snyder, K.A., Robinson, S.A., Schmidt, S., Hultine, K.R. 2022. Stable isotope approaches and opportunities for improving plant conservation. Conservation Physiology. 10(1). Article coac056. https://doi.org/10.1093/conphys/coac056.
Hoover, D.L., Abendroth, L.J., Browning, D.M., Saha, A., Snyder, K.A., Wagle, P., Witthaus, L.M., Baffaut, C., Biederman, J.A., Bosch, D.D., Bracho, R., Busch, D., Clark, P., Ellsworth, P.Z., Fay, P.A., Flerchinger, G.N., Kearney, S.P., Levers, L.R., Saliendra, N.Z., Schmer, M.R., Schomberg, H.H., Scott, R.L. 2022. Indicators of water use efficiency across diverse agroecosystems and spatiotemporal scales. Science of the Total Environment. 864. Article e160992. https://doi.org/10.1016/j.scitotenv.2022.160992.
Young, S.L., Archer, D.W., Blumenthal, D.M., Boyd, C.S., Clark, P., Clements, D.D., Davies, K.W., Derner, J.D., Gaskin, J.F., Hamerlynck, E.P., Hardegree, S.P., Jensen, K.B., Monaco, T.A., Newingham, B.A., Pierson Jr, F.B., Rector, B.G., Sheley, R.L., Toledo, D.N., Vermeire, L.T., Wonkka, C.L. 2023. Invasive annual grasses: re-envisioning approaches in a changing climate. Journal of Soil and Water Conservation. 78(2):95-103. https://doi.org/10.2489/jswc.2023.00074.
Edwards, B.L., Webb, N.P., Van Zee, J.W., Courtright, E.M., Cooper, B.F., Metz, L., Herrick, J.E., Okin, G., Duniway, M.C., Tatarko, J., Tedela, N., Newingham, B.A., Pierson Jr, F.B., Toledo, D.N., Van Pelt, R.S. 2021. Parameterizing an aeolian erosion model for rangelands. Aeolian Research. 54.Article 100769. https://doi.org/10.1016/j.aeolia.2021.100769.