Location: Great Basin Rangelands Research2019 Annual Report
The Great Basin is the largest North American desert covering more than 50 million hectares. Major vegetation types in the Great Basin include: salt desert shadscale/greasewood, sagebrush/bunchgrass and mountain shrublands, pinyon/juniper woodlands, subalpine forests, and alpine tundra. The region has extremely variable climate both spatially and temporally and a complex mixture of public and private land ownership. Ranching, mining, and recreation form the basis of rural economies. Over 20% of Great Basin ecosystems have been significantly altered by invasive plants. This land conversion has resulted in dramatic reductions in forage availability, wildlife habitat, and biodiversity, has increased wildfire frequency and intensity, and altered the hydrologic cycle. Critical research needs addressed in this project are: (1) ecology and control of invasive weeds, (2) rehabilitation of degraded rangelands, (3) maintaining/enhancing healthy rangelands, and (4) quantifying the impact of management practices. Objective 1. Assess and quantify ecological conditions and biotic processes that maintain healthy rangelands, improve forage production, and enhance recovery of degraded sagebrush, and pinyon/juniper woodlands under uncertain climatic conditions in the Great Basin. • Sub-objective 1.1: Expand the ‘genetic toolbox’ to allow us to determine how the reproductive ecology of invasive annuals affects the structure and function of selected Great Basin ecosystems. • Sub-objective 1.2: Determine mechanisms underlying the expansion of native western juniper (Juniperus occidentalis) woodlands. Objective 2. Assess and quantify interactions between annual grasses and fire on watershed processes and ecosystem services under uncertain climatic conditions. Objective 3. Develop and transfer innovative management approaches and technology for conserving and rehabilitating sagebrush, pinyon/juniper woodlands, and salt desert shrublands to meet natural resource and agricultural production goals. • Sub-objective 3.1: Mechanistically understand how intact perennial grass communities resist invasion by annual grasses, especially cheatgrass. • Sub-objective 3.2: Provide management guidelines and transferable technologies to our stakeholders for establishing and enhancing native and introduced grasses, forbs, and shrubs in Great Basin ecosystems. Objective 4. Develop decision support tools for USDA to assess impact of type, location and number of management practices required to meet conservation and agricultural production goals nationwide. • Sub-objective 4.1: Enhance RHEM, KINEROS2, APEX, and SWAT models for assessing hydrology and erosion responses associated with management of disturbed vegetation states and transitions occurring on sagebrush-steppe ecological sites. • Sub-objective 4.2: As part of a national assessment, quantify soil loss on western rangelands.
Objective 1.1: Determine how the reproductive ecology of invasive annuals affects the structure and function of selected Great Basin ecosystems. Hypothesis: Occasional outcrossing facilitates expansion of cheatgrass across the intermountain west by selecting for new genotypes adapted to drier and more alkaline sites. IonTorrent® platform will be utilized to identify new single-nucleotide polymorphisms (SNPs) in cheatgrass to document if outcrossing is occuring. Objective 1.2: Determine mechanisms underlying the expansion of native western juniper woodlands. Hypothesis: Quantify rodent preferences to either juniper berries hand-collected or passed through the gut of a Robin and determine percent germination and seedling establishment between treatments. Objective 2: Assess and quantify interactions between annual grasses and fire on watershed processes and ecosystem services. Hypothesis: Conversion of Wyoming sagebrush community to cheatgrass, as a result of wildfire, will negatively alter runoff and erosion. Rainfall simulation will be used to quantify soil erosion in intact sagebrush and ecosystems converted to annual grass dominance and predict soil erosion with the Rangeland Hydrology and Erosion Model (RHEM). Objective 3.1: Mechanistically understand how intact perennial grass communities resist invasion by cheatgrass. Hypothesis: Healthy, robust, and intact perennial grass communities facilitate resistance to invasion by cheatgrass. Growth of cheatgrass will be contrasted in soil occupied by established perennial grasses and in unoccupied soil in greenhouse and field studies. Objective 3.2: Provide management guidelines and transferable technologies to our stakeholders for establishing and enhancing Great Basin ecosystems. Hypothesis: Combined application of appropriate soil-active herbicides and optimal plant materials will enhance revegetation/restoration success on cheatgrass-infested rangelands. Objective 4: Enhance ARS natural resource models (e.g. RHEM) for assessing hydrology and erosion responses associated with management of disturbed vegetation states and transitions occurring on sagebrush-steppe ecological sites. Hypothesis: Runoff and soil erosion will increase when either pinyon/juniper or annual grasses invade sagebrush-steppe ecosystems. An instrumented watershed, Porter Canyon in central Nevada, will be used to evaluate the impact of cheatgrass invasion and pinyon/juniper woodlands on surface runoff, soil loss and sediment yield. Data will be used to evaluate model performance and measure utility of model to assess conservation practices.
This is the final report for bridging project 2060-13610-002-00D, which was terminated March 24, 2019 and replaced with project 2060-13610-003-00D, “Management and Restoration of Rangeland Ecosystems.” Many of the sub-objectives in the new project which began March 25, 2019 are direct extensions of sub-objectives in the recently expired project and this bridging project, so these essentially constitute continuing research. Continuing areas of research include soil erosion and salt transport on rangelands, expansion of native conifer woodlands, cheatgrass population genetics, passive restoration techniques using the seed dispersal services of native animals, and fire ecology. Research activities during the period covered by this report involved attending to details to finish the terminated project (e.g., revising manuscripts that are in the review process, reanalyzing data if needed for revisions, etc.), preparing for the research proposed in the new project with such preliminary tasks as site selection and acquiring necessary permits, or preparing additional manuscripts that were unforeseen, but motivated from research results from the previous project. For additional information, see the report for 2060-13610-003-00D. In support of Sub-objective 1.1, a journal article was published indicating that many of the thousands of simple sequence repeat DNA markers (SSRs) that have been developed for bread wheat are likely to also be applicable to cheatgrass genetic studies. DNASTAR Lasergene SeqNinja software was used to identify single nucleotide polymorphisms (SNPs) throughout the cheatgrass genome. For Sub-objective 1.2, journal articles have been published demonstrating that various fruit-eating bird species (e.g., American robins, Townsend’s solitaires, cedar waxwings) consume berries of western juniper and defecate the seeds, and seed-caching small mammals (e.g, yellow pine chipmunks, California kangaroo rats, pinyon mice) are secondary dispersers of juniper seeds defecated by birds. Quantitative data from this work will be used to parameterize predictive models of western juniper expansion. Sampling of Utah juniper berries was conducted at five sites in western and central Nevada. Berries were frozen for later inspection for arthropod seed predators. Under Objective 2, plots were being monitored on the Strawberry Fire to assess herbicide and seeding treatment effects on plant establishment and soil properties. Two new experimental sites were established in Nevada and Utah to examine the effects of post-fire grazing on surviving perennial grasses. Plants were marked and measured and grazing treatments were applied. Progress on Objective 3 included collaborating with the Bureau of Land Management (BLM). The BLM applies post-fire rehabilitation treatments after fire to assist ecosystem recovery and minimize impacts to soil stability, air and water quality, annual invasive grass expansion, wildlife habitat, forage production, and recreational use. ARS scientists advised BLM staff on post-fire Emergency Stabilization and Rehabilitation (ESR) plans and monitoring design in the Great Basin. Assistance included: 1) identifying key areas, 2) identifying key monitoring questions, 3) sampling design development, 4) sampling method recommendations, 5) data collection, 6) weather and soils instrument setup and readout, 7) data analysis, 8) report writing, and 9) presentations of findings. We are continually advising on eight fires from 2013-2019 and have contributed to two ESR plans submitted for ESR funding this year. We have also developed protocols for each fire to monitor soils in addition to plants, including biological soil crust, soil moisture sensors, and dust traps. Diversionary seeding, which manipulates the natural seed dispersal services provided by seed-caching animals was demonstrated to enhance productivity of Indian ricegrass, and new approaches deploying the diversionary seeding strategy were detailed in two journal articles. Progress was made on Sub-objective 4.1, in which annual rainfall simulation experiments have been (and continue to be) conducted at multiple sites to quantify erosion rates on Colorado Plateau rangelands. In support of Sub-objective 4.2, research was carried out in assessing the impact of wind erosion as a major contributor to rangeland soil degradation. The goal is to determine the extent of soil loss due to wind erosion. Partnering with other ARS scientists, Natural Resources Conservation Service (NRCS), BLM, U.S. Geological Survey (USGS), Department of Defense (DoD), and The Nature Conservancy (TNC). The National Wind Erosion Network (NWERN) has been developed, which currently has 14 sites across U.S. rangelands. Sites are provided soil and meteorological instrumentation in order to assess dust flux and associated processes. The NWERN will 1) provide standardized data to support understanding of wind erosion processes across land use and land cover types and for different management strategies, 2) support the development of open-access technologies to assess wind erosion and dust emission that integrate new data sources and complement existing monitoring programs, and 3) encourage collaboration among scientists, resource managers, and policymakers to develop opportunities for enhancing wind erosion monitoring and assessment for scientific and land management applications.
1. Insects and mites reduce western juniper seed production. ARS scientists at Reno, Nevada, have identified numerous insects and one mite species that inhabit the berries and seeds of western juniper, the most rapidly expanding native tree species on western rangelands. The mite and at least seven of the insect species can cause damage that renders juniper seeds inviable. A paper was published describing the four most common species that damage seeds, levels of damage they cause, and yearly variation in their population sizes. Two of the four species have clearly been identified as possessing the greatest impacts on western juniper seed production. Recognizing outbreaks of these seed-damaging species can assist managers in prioritizing where to apply limited resources into juniper control measures. Mass rearing some insects that limit western juniper seed production for biological control applications in areas where juniper is expanding may also be an option.
2. Invasive plants alter hydrological cycles. Kentucky bluegrass (Poa pratensis L.) can serve to stabilize soils and increase site stability; however, it also alters nutrient flows, soil structure, and plant community composition, ultimately degrading biotic integrity. Scientists at Reno, Nevada, and Mandan, North Dakota, evaluated the impact of Kentucky Bluegrass on hydrologic processes. They found that on dry soils Kentucky Blue grass increased runoff. However, on wet soil Kentucky Bluegrass reduced runoff over native prairie. The impact of Kentucky bluegrass on overall biotic integrity and hydrologic processes will depend on weather patterns and the ratio of precipitation on dry and wet soils.
Vuono, D.C., Read, R.W., Hemp, J., Sullivan, B., Arnone, J.A., Neveux, I., Blank, R.R., Staube, C., Loney, E., Miceli, D., Winkler, M., Chakraborty, R., Stahl, D., Grzymski, J. 2019. Resource concentration modulates the fate of dissimilated nitrogen in a dual-pathway actinobacterium. Frontiers in Microbiology. 10:3. https://doi.org/10.3389/fmicb.2019.00003.
Clements, D.D., Harmon, D.N., Blank, R.R., Weltz, M.A. 2017. Improving seeding success on cheatgrass infested rangelands in northern Nevada. Rangelands. 39(6):174-181. https://doi.org/10.1016/j.rala.2017.10.003.
Dimitri, L.A., Longland, W.S. 2017. Distribution of western juniper seeds across an ecotone and implications for seed dispersal processes. Western North American Naturalist. 77:212-222.
Vander Wall, S.B., Dimitri, L.A., Longland, W.S., White, J. 2019. Seed value influences cache pilfering rates by desert rodents. Integrative Zoology. 14(1):75-86. https://doi.org/10.1111/1749-4877.12358.
Longland, W.S., Dimitri, L.A. 2018. Interaction between seed detectability and seed preference affects harvest rates of granivorous rodents. Western North American Naturalist. 78(2):195-203. https://doi.org/10.3398/064.078.0210.
Clements, D.D., Jenkins, R. 2017. Managing cheatgrass in rangeland restoration efforts. The Progressive Rancher. 17(8):24-28.
Snyder, K.A., Huntington, J.L., Wehan, B., Morton, C., Stringham, T.K. 2019. Comparison of landsat and land-based phenology camera normalized difference vegetation index (NDVI) for dominant plant communities in the Great Basin. Sensors. 19(5):1139. https://doi.org/10.3390/s19051139.
Williams, C.J., Snyder, K.A., Pierson Jr, F.B. 2018. Spatial and temporal variability of the impacts of pinyon and juniper reduction on hydrologic and erosion processes across climatic gradients in the Western US: A regional synthesis. Water. 10(11). https://doi.org/10.3390/w10111607.
Snyder, K.A., Evers, L., Chambers, J., Dunham, J., Bradford, J., Loik, M. 2018. Effects of a changing climate on the hydrological cycle in cold desert ecosystems in the Great Basin and Columbia Plateau. Rangeland Ecology and Management. 72(1):1-12. https://doi.org/10.1016/j.rama.2018.07.007.