Location: Great Basin Rangelands Research2019 Annual Report
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)
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.
This report documents progress for project 2060-13610-003-00D entitled “Management and Restoration of Rangeland Ecosystems,” which started in March 25, 2019, and continues research from bridging project 2060-13610-002-00D entitled “Invasive Species Assessment and Control to Enhance Sustainability of Great Basin Rangelands.” Because only three months have elapsed between the initiation of the new project and drafting this report, some sub-objectives in the new plan have not yet been addressed. The following summarizes the progress that has been made on sub-objectives since the initiation of the new project plan. Under Sub-objective 1A, research focused on how salinity in rivers effects every aspect of life from drinking water, to use by industry, and agricultural production. The Upper Colorado River has natural and anthropogenic sources of salinity. Researcher’s at ARS developed a project with University of Nevada-Reno and Bureau of Land Management (BLM) colleagues to develop new predictive tools to assess the risk of salt transport during storm flow. The team evaluated nine sites across Utah and Colorado and develop new predictive equations to assess risk of salt loading and the amount of salt being transfer across the land as a function of storm intensity. This tool will allow BLM and Natural Resources Conservation Service (NRCS) to understand where the landscape conservation and load management practices could be implemented to reduce salt transport into the Colorado River. In support of Sub-objective 1B, research focused on how fire not only affects water erosion and associated watershed processes, but also affects wind erosion due to exposed soil for several months after fire. Since little information exists about the effects of fire on wind erosion. ARS scientists from Reno, Nevada, are collaborating with BLM, and two wind erosion sites associated with the National Wind Erosion Network (NWERN) have been installed in northern Nevada at the Martin Fire, which burned in July 2018. Measurements include temperature, relative humidity, precipitation, wind speed, and direction, saltation, dust flux, soil particle size distribution, soil surface roughness, aggregate size distribution, biological soil crust, and vegetation. Additionally, we are working with the BLM on establishing protocols to measure soils and biological soil crust in addition to vegetation on fires. This includes measuring soil texture, structure, moisture, and establishing dust traps on all fires. Soil monitoring will allow BLM managers to achieve their goal of soil stabilization. Two common post-fire rehabilitation treatments in areas prone to annual grass invasion include herbicide application and subsequent seeding with perennial species. Although this is common practice, we lack knowledge on how these combined treatments affect plant communities and soil properties. We established an experiment on the Strawberry Fire near Great Basin National Park (GBNP) in collaboration with BLM and National Park Service (NPS) to assess the effects of herbicide and seeding treatments. Fifty plots were established in spring 2017, glyphosate herbicide was applied, and we continue to measure soil stability, texture, chemistry, biological crust, and plant cover. Initial results showed glyphosate decreased cheatgrass cover; however, glyphosate eliminated the native plant, coyote tobacco. Monitoring changes in plant communities, soil properties, and plant invasions will allow us to advise BLM managers on future rehabilitation treatments. Progress was made on Sub-objective 1C in which data collection in the Porter Canyon Experimental Watershed (PCEW) in the Desatoya Mountain Range is now in its ninth year. This data will help to develop tools and strategies for arid rangeland ecosystems based on an integrated understanding of plant and soil relationships. Results from plant phenology cameras and environmental sensors in PCEW were analyzed and published this year. Collaboration with scientists at Las Cruces, New Mexico produced a summary paper on the uses of plant phenology cameras in rangelands. Additional funds were obtained to instrument several high elevation meadows in the Desatoya Mountains. Over grazing by cattle and wild horses can lead to groundwater declines and degradation of meadow habitat. Meadow habitat is critical to the survival of juvenile sage grouse, a species of concern. The Desatoya Mountains have 437 wild horses which is four times the established carrying capacity. We instrumented four high elevation meadows with plant phenology cameras, weather stations, snow depth sensors and soil moisture sensors to track plant growth over the growing season. The BLM is planning to install exclusionary fencing in three of the four meadows this fall. This will be a fully replicated grazing experiment to determine the effects of exclusionary fencing on: meadow species composition, timing and peak of plant greenness, and changes in soil moisture. In support of Sub-objective 1D, genetic variation among cheatgrass samples from 20 Great Basin and Mojave sites representing a diversity of environments and from European populations within the native range of the plant was assessed using sequencing data. These data are currently being analyzed in collaboration with a bioinformatics specialist from the University of Nevada-Reno using program STRUCTURE to determine genetic similarities and distances of the different populations. This will indicate how local genetic variation in the introduced range of cheatgrass is related to ecological site conditions, and how such relationships derived from genotypes occurring in the native range. Progress on Sub-objective 2A focused on how native perennial bunchgrasses are often seeded and domestic livestock grazing is often delayed two growing-seasons after wildfire in the GBNP. Seeding failures often occur due to unsuitable abiotic conditions or inappropriate post-fire management. An experiment was established to examine 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. 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. For Sub-objective 2B, western juniper berries were sampled at established Northern California field sites, Utah juniper berries at new sites in western and central Nevada (near Carson City and Austin, Nevada, respectively), and California juniper berries at several new sites located throughout central and southern California. In the lab we dissected at least 100 berries for every tree sampled (20-100 trees per site) and collected larvae from insect species that damage juniper seeds, as well as reared adult arthropods from mass berry collections. To date, we have identified 37 insect species and one mite species that occur within western juniper berries, at least seven of which are seed predators that render seeds inviable. The recent expansion of this work to include Utah and California juniper is generally finding the same or closely related seed predators in berries of these species. This research will determine if arthropod damage to juniper seeds is primarily accomplished by one or a few species or is attributable to a greater variety of species. This is an essential first step for potential biological control applications, and it has immediate utility for parameterizing models of juniper expansion.
1. New tools for peak production. Rangeland managers require timely, reliable, and easily understandable information about the condition of their land to make informed decisions. One of the challenges managers face is variability in plant phenology which includes the timing of plant establishment, growth, peak production and reproduction. These data traditionally were collected by field visits which are costly and time intensive. A scientist at Reno, Nevada, and a scientist at Las Cruces, New Mexico, established land-based plant phenology cameras in dominant ecosystems of the Great Basin and Chihuahuan Desert and determined that these relatively inexpensive cameras can be used to quantify phenological changes in mixed shrub-grasslands and meadow ecosystems. Plant “phenocams” offer a powerful and underutilized technology to increase management effectiveness through precision timing. Applications include determining the timing of peak greenness for grazing, herbicide application, and opportunities to reduce fuel loads.
2. Big sagebrush stand densities. Reoccurring wildfires have significantly decreased big sagebrush stand densities resulting in loss of critical shrub habitat for sagebrush obligate species such as sage grouse. Scientists at Reno, Nevada, evaluated big sagebrush transplanting methodologies to increase big sagebrush density in crested wheatgrass stands. New approaches that were tested resulted in a six-fold increase in big sagebrush density for sagebrush obligate species by use of proper methodologies in the fall versus spring transplanting of big sagebrush into crested wheatgrass stands. This increase in sagebrush density significantly enhanced the habitat for sagebrush obligate species and will decrease livestock-wildlife conflicts that hinder grazing on public lands.
3. Degradation of native rangelands. Degradation of rangelands from wildfires has converted millions of acres of native rangelands to be dominated by the invasive and exotic annual grass, cheatgrass, causing significant loss of critical browse communities for wildlife and livestock. Scientists at Reno, Nevada, initiated and tested new transplanting and seeding methods to reestablish the critical browse plant, antelope bitterbrush following an extensive wildfire in northern Nevada. Transplanting of antelope bitterbrush resulted in an initial establishment of over 100 new antelope bitterbrush/acre while the seeding of antelope bitterbrush had initial establishment of over 15,000 antelope bitterbrush seedlings/acre. The research was successful in demonstrating cost-effective techniques that significantly increased the establishment and recruitment of this critical species that significantly improved nutritional forage for numerous wildlife species as well as domestic livestock and prevented conversion of the area to cheatgrass dominance.
Clements, D.D., Harmon, D.N. 2019. Survivability of Wyoming big sagebrush transplants. Rangelands. 41(2):88-93. https://doi.org/10.1016/j.rala.2018.11.008.
Smith, A.G., Newingham, B.A., Hudak, A., Bright, B.C. 2019. Got shrubs? Climate mediates long-term shrub and introduced grass dynamics in chaparral communities after fire. Fire Ecology. 15:12. https://doi.org/10.1186/s42408-019-0031-2.
Browning, D.M., Snyder, K.A., Herrick, J.E. 2019. Plant phenology: Taking the pulse of rangelands. Rangelands. 41(3):129-134. https://doi.org/10.1016/j.rala.2019.02.001.