Research Project: Management and Restoration of Rangeland Ecosystems

Location: Great Basin Rangelands Research

2024 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 the final report for project 2060-13610-003-000D, "Management and Restoration of Rangeland Ecosystems", which has been replaced by new project 2060-21500-001-000D, "System-based Management and Rehabilitation of Rangelands". For additional information please see the new project report. In support of Sub-objective 1A/Hypothesis 1A, ARS researchers in Reno, Nevada, conducted rainfall simulations on the Colorado Plateau. The Upper Colorado River has natural and anthropogenic sources of salinity. ARS researchers, developed a project with University of Nevada, Reno (UNR), Desert Research Institute (DRI), and Bureau of Land Management (BLM) colleagues to develop new predictive tools to assess risk of salt transport during storm flow at hillslope and watershed scales. The team evaluated nine sites in Utah and Colorado, developing predictive equations to quantify salt loading and salt transfer across the land as a function of storm intensity. The team developed methods to assess which watersheds in the Upper Colorado River Basin had the highest risk for contributing salt loading to the Colorado River. This enabled tracking of salt redistribution into the soil during a rainfall event and partitioning remaining salt that was available to be transported overland and potentially reach the river. This team of researchers released a new version of the Rangeland Hydrology and Erosion Model (RHEM), Version 2.4 updated 1/12/2022 which was approved by National Resources Conservation Service in 2020. This research was summarized in five published manuscripts. Also, in support of Sub-objective 1B/Research Goal 1B.1, researchers released the Rangeland Hydrology and Erosion Model User Guide and the Rangeland Hydrology Handbook. The Research Hydrologist on these projects retired in December of 2021 and is one of the current critical vacancies. Supporting Sub-objective 1B/Research Goal 1B.2, experiments continued 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 land effected by 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 fluxes 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 further 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. Two manuscripts were published in relation to wildfire and wind erosion, as well as incorporating wind erosion into land health assessments. Under Sub-objective 1C/Hypotheses 1C.1 & 1C.2, ARS researchers continued to collect data from the Porter Canyon Experimental Watershed. Measurements include depth to groundwater, images from plant phenology cameras, soil moisture, soil temperature, streamflow, and micrometeorological variables. This watershed was established to address stakeholder concerns regarding the effects of various treatments to reduce pinyon and juniper in areas formerly dominated by sagebrush and forage grasses. Detailed hydrologic data is being collected and plant community composition and phenology are measured. Over the lifetime of this project, multiple experiments and observational studies have been conducted in this watershed that have quantified the amount of rainfall interception by pinyon and juniper trees, as well as the amount intercepted by Mountain Big Sagebrush. A manuscript and several presentations were prepared summarizing six years of water use by pinyon and juniper trees. A manuscript was submitted that quantified how much stemflow generated during rainstorms was used by pinyon and juniper trees using simulated stemflow events with isotopically-labelled water. Researchers in Reno, Nevada, and Tucson, Arizona, contributed to a General Technical Report summarizing the state of the knowledge on the ecology, history, and management of pinyon and juniper woodlands in the Great Basin and northern Colorado Plateau of the Western United States. For Sub-objective 1C/Hypothesis 1C.3, ARS researchers used cameras to quantify plant phenological stage with variable weather over multiple years. Eighteen cameras were deployed over the years to measure plant phenology in dominant Great Basin communities including pinyon and juniper, sagebrush, and meadow systems. A suite of nine cameras were focused on groundwater dependent meadow systems because these areas, while small in areal extent, provide a disproportionate (i.e., high) level of ecosystem goods and services. A replicated grazing experiment was conducted for three years with no grazing, controlled grazing by domestic livestock, and uncontrolled grazing by both domestic livestock and feral horses. Results of this experiment were summarized in two published manuscripts. A third published manuscript quantified shifts in sage-grouse arthropod food sources across the grazing treatments and environmental gradients. In support of Sub-objective 1D/Hypothesis 1D, DNA sequencing was conducted on cheatgrass samples collected from sites throughout the Great Basin and Mojave regions and from several European populations within the native range of the plant. Two ARS scientists in Reno, Nevada, collaborated with a UNR bioinformatics specialist to analyze sequencing data using DNASTAR Lasergene software and generate single nucleotide polymorphism (SNP) markers for characterizing specific cheatgrass genotypes. Analyses using these SNPs improved our understanding of cheatgrass invasion processes and helped direct searches for effective biocontrol agents by identifying native range origins of U.S. cheatgrass populations. Due to critical vacancies of a Research Ecologist, and relocation of Research Entomologist to a different ARS location, no progress was made on the genetic mapping of cheatgrass beyond FY 2022. In support of Sub-objective 2A, ARS researchers 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. ARS 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. A manuscript and a MS student thesis were submitted. 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. For Sub-objective 2B, ARS researchers made progress on quantifying the effects of arthropod seed predators in reducing seed viability of western and Utah juniper as a potential pre-establishment control strategy. This included sampling of juniper berries at three western juniper sites in northern California and at five Utah juniper sites in western and central Nevada. This project identified 38 insect species and one mite species that occur within western juniper berries, at least seven of which are seed predators that render seeds inviable. This is an essential first step for potential biological control applications, and it has immediate utility for parameterizing models of juniper expansion. Three manuscripts were published that addressed the diversity of arthropods in juniper berries and the damage incurred to juniper berry viability. The Research Ecologist on this project retired in December of 2021 and is one of the current critical vacancies. Supporting Sub-objective 2C, ARS researchers conducted several experiments on manipulating the behavior of granivorous rodents through the addition of preferred diversionary seeds to field plots. Collectively, desert rodent species constitute the most important consumers of seeds on arid western rangelands. Some rodents also provide important seed dispersal benefits to certain plants through seed caching activities. The diversionary seeding concept involves broadcasting inexpensive, commercially available seeds (i.e., “diversionary” seeds) to reduce the rate that granivorous rodents consume seeds of an alternate plant species that is a target for restoration efforts. Results of these experiments were published in six manuscripts.

Accomplishments
1. Framework linking erosion models and land health assessments. Wind and water erosion are prominent forces in rangelands, resulting in loss of soil carbon and reduced plant productivity. However, managers lack tools to integrate erosion models with widely-used land health assessments. Using a newly developed wind erosion model, as well as a water erosion model, ARS researchers in Reno, Nevada; Las Cruces, New Mexico; Tucson, Arizona; and Mandan, North Dakota, developed a framework suggesting how managers can improve land health assessments by incorporating information from the erosion models. This framework provides managers with additional lines of evidence to support assessments and increase assessment consistency by incorporating quantitative modeling.

2. Wind erosion in the Great Basin. Wind erosion in aridlands can result in soil carbon loss, affect plant productivity, and cause human health impacts and driving accidents. Perhaps due to its remote nature, little has been known about wind erosion processes in the Great Basin, particularly erosion caused by disturbances. ARS researchers in Reno, Nevada, and Las Cruces, New Mexico, used a recently developed wind erosion model to predict wind erosion in the Great Basin in relation to wildfire and invasive species. These results provided crucial information into how wildfire and plant community responses may affect wind erosion risk, which will assist land managers in determining appropriate treatments to facilitate soil stability in rangelands.

3. A tool for remotely monitoring grazing and plant phenology for adaptive management. In the Great Basin, groundwater dependent ecosystems (GDEs), such as meadows, provide forage for livestock and habitat for a threatened keystone species, the greater sage-grouse. However, GDEs are notoriously hard to manage and need adaptive management to serve both agricultural and non-agriculture values. ARS researchers in Reno, Nevada, and Las Cruces, New Mexico, with collaborators from the University of Nevada, Reno, were able to successfully combine on-the-ground measurements of phenology with plant phenology camera indices, and indices of plant vigor and gross primary production from the Landsat platform. This research demonstrated that managed grazing that removes cattle at 10 cm stubble height can conserve soil moisture and extend the growing season, thus providing forage later in the season for cattle, while still providing the critical mix of plant functional types for the greater sage-grouse. Due to the vast landscapes in the Great Basin, automated methods to provide crucial information on peak plant production and the timing of grazing, can save valuable fiscal and human resources, which will assist managers in determining appropriate strategies to facilitate extending the growing season for forage production.

4. Woody plant encroachment and the water budget. In the Intermountain West, native pinyon and juniper have expanded over 10-fold post-European arrival. Millions of dollars have been spent on pinyon and juniper control to re-direct limited water resources to rangeland systems that provide livestock forage. An ARS researcher in Reno, Nevada, instrumented the Porter Canyon Experimental Watershed (PCEW), the only one in Nevada designed to assess woody plant control effects on the water budget. Rainfall experiments and six-years of data on the water use of pinyon and juniper, have demonstrated that pinyon and juniper can significantly reduce incoming precipitation, through interception, evaporation, and plant transpiration. Results of this research are critical to accurately parameterize models of the water budget in these areas encroached by woody plants that were formerly productive rangeland ecosystems.

Review Publications
Richardson, W., Stringham, T.K., Nuss, A.B., Morra, B., Snyder, K.A. 2023. Shifts in sage-grouse arthropod food sources across grazing and environmental gradients in upland meadow communities. Journal of Environmental Management. 348. Article 119261. https://doi.org/10.1016/j.jenvman.2023.119261.
Williams, C., Ellsworth, L.M., Strand, E.K., Reeves, M., Shaff, S.E., Short, K.C., Chambers, J.C., Newingham, B.A., Tortorelli, C. 2023. Fuel treatments in shrublands experiencing pinyon and juniper expansion result in trade-offs between desired vegetation and increased fire behavior. Fire Ecology. 19. Article 46. https://doi.org/10.1186/s42408-023-00201-7.
Young, S.L., Anderson, J.V., Baerson, S.R., Bajsa Hirschel, J.N., Blumenthal, D.M., Boyd, C.S., Boyette, C.D., Brennan, E.B., Cantrell, C.L., Chao, W.S., Chee Sanford, J.C., Clements, D.D., Dray Jr, F.A., Duke, S.O., Porter, K.M., Fletcher, R.S., Fulcher, M.R., Gaskin, J., Grewell, B.J., Hamerlynck, E.P., Hoagland, R.E., Horvath, D.P., Law, E.P., Madsen, J., Martin, D.E., Mattox, C.M., Mirsky, S.B., Molin, W.T., Moran, P.J., Mueller, R.C., Nandula, V.K., Newingham, B.A., Pan, Z., Porensky, L.M., Pratt, P.D., Price, A.J., Rector, B.G., Reddy, K.N., Sheley, R.L., Smith, L., Smith, M., Snyder, K.A., Tancos, M.A., West, N.M., Wheeler, G.S., Williams, M., Wolf, J.E., Wonkka, C.L., Wright, A.A., Xi, J., Ziska, L.H. 2023. Agricultural Research Service weed science research: past, present, and future. Weed Science. 71(4):312-327. https://doi.org/10.1017/wsc.2023.31.
Treminio, R.S., Webb, N.P., Edwards, B.L., Faist, A., Newingham, B.A., Kachergis, E. 2024. Spatial patterns and controls on wind erosion in the Great Basin. Journal of Geophysical Research-Biogeosciences. 129(1). Article e2023JG007792. https://doi.org/10.1029/2023JG007792.