Research Project: Development of Ecological Strategies for Invasive Plant Management and Rehabilitation of Western Rangelands

Location: Great Basin Rangelands Research

2021 Annual Report

Objectives
The Great Basin covers approximately 54 million hectares of the western United States with ranching, mining, and recreation as the primary economic activities. Invasive annual grasses and expanding native conifer populations have significantly altered ecosystems on over 20% of the Great Basin. Changes in plant type and cover, together with climate variability, drought, and land conversion have resulted in dramatic reductions in available forage and wildlife habitat, while increasing the frequency and intensity of wildfires. Public awareness of the impacts of invasive weeds has produced conflicts regarding proper rangeland management strategies. The research proposed here will produce critical data regarding the development of complementary control strategies to address 1) biological, chemical, and cultural control of the most important invasive annual grass species: cheatgrass (Anisantha tectorum), red brome (A. rubens), and medusahead (Taeniatherum caput-medusae); and 2) the effects of woodland encroachment on water resource availability. Research will focus on the discovery and evaluation of arthropods as biological control agents against invasive annual grasses; development of methods to revegetate rangelands degraded by wildfire with plant species that can prevent reinvasion of annual grasses and other noxious weeds, while enhancing biological diversity and forage for grazing animals; and assessment of water use by native conifer populations that are replacing grazable range. Resulting management guidelines and tools will facilitate sustainable delivery of goods and services from Great Basin ecosystems to agricultural producers and land managers, while mitigating the deleterious effects of weeds and wildfires. Objective 1: Discover and evaluate new biological control candidates for invasive annual grasses i.e., medusahead, cheatgrass, and red brome to develop new biological control strategies. [NP304, C2, PS2B] · Sub-objective 1A: Conduct field surveys to discover, identify, and collect natural enemies of medusahead, cheatgrass, and red brome. · Sub-objective 1B: Evaluate candidate biological control agents of medusahead, cheatgrass, and red brome for their suitability for release in the Great Basin and adjacent invaded regions. Objective 2: Analyze the distribution of limited resources critical for plant growth between native and invasive plants, soil properties, and hydrologic processes on degraded rangelands to improve rangeland conservation and rehabilitation strategies. [NP304, C2, PS2B] · Sub-objective 2A: Assess the effects of pre- and post-emergent herbicides on invasive cheatgrass populations and on the rehabilitation of ecosystems after wildfire. · Sub-objective 2B: Investigate and quantify critical water resources of rangelands, including water use of pinyon and juniper and hydrologic responses of a meadow to tree control.

Approach
Foreign surveys for natural enemies of medusahead, red brome and cheatgrass in their native ranges will be conducted by a team of collaborators led by ARS-Reno, in coordination with European and other ARS partners. Efforts will be made to visit each surveyed target weed population at least once in all seasons over the course of the project in order to observe all plant phenological stages and their associated natural enemies. New natural enemies of targeted annual grass species that are discovered in the course of these surveys will be prepared for evaluation as candidate biocontrol agents (CBCAs), including testing of host-range and the potential for each CBCA to reduce target weed populations. Target weed populations will also be surveyed in the Great Basin to determine if native-range natural enemies are already present. Genetic markers will be used to reveal precise relationships between geographically separated populations of CBCAs. The efficacy of three soil-active pre-emergent herbicides, Imazapic (Plateau), Sulfometuron methyl-Chlorsulfuron (Landmark XP), and Indaziflam (Esplanade), to reduce cheatgrass and its associated seed bank will be tested. Herbicides will be applied in the fall on two recently-burned Wyoming-sagebrush sites, as well as on adjacent unburned areas infested with cheatgrass. Seed mixes (native and introduced species) will also be evaluated for their ability re-establish persistent, desirable plant communities. A weather will be established station at each research site to record amount and time of precipitation events. Plant and soil attributes will be measured bi-monthly over the entire year. Foliar cover, seedling emergence, mortality, persistence, and density of all test plant species, as well as cheatgrass seed bank density, will be estimated and species diversity and richness will be calculated. Effects of herbicides and seeding treatments on native plants, invasive species, biological soil crust, and soil properties will be evaluated. Pinyon and juniper trees will be instrumented with heat dissipation probes to measure transpiration at Porter Canyon Experimental Watershed (PCEW) in plant communities dominated by pinyon-juniper, sagebrush steppe, and meadows (where groundwater springs occur). Locations will include a valley bottom site and east- and west-facing hill slopes. Additional trees will be instrumented with variable depth probes to control for reductions in flow with depth of xylem area. Stems will be collected from trees to extract xylem water to determine the source of transpiration water from these trees using stable isotopic analyses of hydrogen and oxygen in plant xylem water. In addition, the effects of mechanical tree removal on a downslope meadow system will be quantified by measuring changes in ephemeral flow and groundwater levels relative to eight years of baseline data. Vegetation transects will be measured annually to quantify tree removal treatments on groundwater depth, soil, moisture, meadow community composition, and peak of seasonal greenness

Progress Report
Research in support of Objective 1 continued, but was delayed due to the COVID-19 pandemic, with the inability of ARS scientists and foreign collaborators to conduct essential international travel in the Eurasian native ranges of the targeted weeds species. Substantial progress was made on Sub-objective 1A by in-country collaborators in the weeds’ native ranges, but still much less than under normal circumstances. Establishment of laboratory colonies of recently discovered biocontrol candidates of cheatgrass and medusahead, a key goal of most other planned FY21 research in Objective 1, was impossible due to travel restrictions, but hope to resume work in Spring 2022. As field work became safer and more feasible in the Great Basin and surrounding regions in early 2021, we were able to make planned collections of targeted invasive weeds in California, Idaho, Nevada, Oregon, and Washington, in order to monitor the existence and extent of natural enemy populations of targeted weeds in their invaded ranges in the western United States. Progress was made in support of Sub-objective 2A, in which herbicide treatments were initiated to control cheatgrass at several sites in north-central Nevada. In separate treatments, the same sites were sown with native and introduced plant species to compete with invasive cheatgrass populations. Soil samples were taken and analyzed to determine fate and activity of the herbicides applied along with soil nutrients to determine and help understand the impacts of invasion by cheatgrass on soils, and when and where treatments will be successful. All treatments were sampled to determine emergence of seeded species by species and persistence throughout the year. Drought had significant impact on new seeding implemented in fall of 2020. Spring 2021 measurements indicated failure of seeding treatments due to drought. Plots will be reseeded in fall of 2021 if environmental conditions are favorable. On established seedings, plants were persistent, weathering the drought and providing critical forage (increase of over 300%) for wildlife and livestock. Fuels loads were greatly diminished (greater than 85%) due to the success of seeding treatments. 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. In support of Sub-objective 2A, progress was made in establishing an experiment on land burnt in the Strawberry fire near Great Basin National Park in eastern Nevada, in collaboration with the Bureau of Land Management and the National Park Service, to assess the effects of herbicide and seeding treatments. In a factorial design, we applied two herbicide treatments: no herbicide and spring glyphosate (post-emergence); and three native seeding treatments, which included no seeding, all-terrain vehicle (ATV) seeding with a pipe harrow, and hand seeding (i.e. no soil surface disturbance). Seeding treatments were applied at two rates: 10.21 and 15.31 kg/hectare. Unburned plots were also established outside the fire perimeter as a control. Plots are 50x60 meters with four replicates per treatment (10 treatments, 40 plots total). The herbicide treatment was applied the first spring after the fire, and the seeding treatment was applied the following autumn. Plant cover, plant height, gap intercept, and biological soil crust cover were measured at peak growing season and soil samples were taken for soil chemistry analysis. To characterize the soil physical environment, we installed soil moisture and temperature probes. Soil stability was measured using a modified slake test and soil surface roughness was measured using a microrelief meter. Preliminary analyses showed glyphosate initially reduced cheatgrass cover. Seeding rate had no effect on seeded species. The methods portion of the manuscript has been written. Progress was made on Sub-objective 2B with eight years of data being collected from trees instrumented with heat dissipation probes to measure tree sap flow velocity. This data has now been analyzed for outliers, creating a structured query language (SQL-lite) database that can be queried by species, site, tree size, and date. Sap velocity measures the volume of water per unit and time used for plant transpiration. In order to scale to the whole tree, several additional steps were taken. Our research found that sap flow decreased with xylem depth for pinyon but not for juniper. Therefore, for juniper, whole tree sap flow was calculated by taking allometric measurements that related tree basal diameter to sapwood length, then multiplying by sap flow velocity. However, for pinyon, we used a Bayesian model to describe how sap flow decreased with xylem depth, based on four trees instrumented with heat dissipation probes at increasing 2 centimeter (cm) depths. This dataset is now being analyzed to determine yearly variations in sap flow for whole trees at three different sites and a manuscript is being prepared. We collected our 11th year of data on groundwater levels and streamflow in four instrumented flumes. The Bureau of Land Management is continuing to harvest trees within Porter Canyon this summer. These measurements in conjunction with understory vegetation measurements and plant phenological cameras will assess the recovery responses of these wet, mesic, and dry meadows. In collaboration with Brigham Young University, progress was made in support of Sub-objective 2B, by successfully installing and monitoring plots seeded with native species and coated with different seed coatings. These plots were located within the area burnt by the Martin Fire in Nevada. These seed coatings are formulated to facilitate the germination and emergence of native species in areas that have recently experienced catastrophic fire. ARS scientists from Reno, Nevada, and Kimberly, Idaho, worked on developing miniature cameras. A prototype is being built using commercially available components for a cost of less than $120.00 per unit. These cameras will be tested in future field experiments to determine if they can allow us to remotely monitor seedling germination, emergence, and survival.

Accomplishments
1. Restoration of critical habitat decrease fuelnloads, risk of wildfire and increase forage availability. ARS scientists in Reno, Nevada, tested transplanting methodologies of Wyoming big sagebrush and antelope bitterbrush as well as direct seeding methodologies of these two shrub species with perennial grasses to increase shrub densities and associated nutritional values as well as establish perennial grasses to improve grazing resources and aid in the suppression of cheatgrass and associated fuel loads. Transplanting was the most successful method in the establishment of Wyoming big sagebrush, while direct seeding was more beneficial to antelope bitterbrush. Seeding of perennial grasses at proper seeding rates did not limit shrub establishment and resulted in the decrease of cheatgrass fuel loads. Using proper restoration methodologies, fall transplanting and rangeland drill seeding using prescribed seeding rates increased critical browse species by more than 400% and perennial grass densities increased by more than 600%, while decreasing cheatgrass densities and associated fuels by more than 85%, therefore providing sustainable grazing and wildlife resources.

2. Pre-emergent herbicides and seeding reduce fuel loads and risk of wildfire. ARS scientists in Reno, Nevada, in cooperation with local, state, and federal partners, initiated an aggressive approach using an integrated approach of using pre-emergent herbicides to control cheatgrass and other annual weeds along with seeding methodologies of desirable perennial species to restore critical grazing and wildlife resources. Using an integrated approach of aggressive and effective weed control with pre-emergent herbicides and proper seed mixes resulted in high levels of success of perennial grasses, shrubs, and forbs. Perennial grass densities from seeding operations have increased by four-fold while cheatgrass densities and associated fuels have decreased by more than 80%. Aerial seeding of Wyoming big sagebrush and western yarrow on selected habitats have resulted in high levels of success critical to such wildlife species as sage grouse and mule deer.

3. Foundation laid for Great Basin and sagebrush biome ecological research. ARS researchers from Reno, Nevada, published seminal documents that lay the foundation for future ecological research in the western United States. The first is an ARS-led synthesis of all climate change research to date in the Great Basin, which covers approximately six percent of the land area of the continental United States. The far-reaching impact of this 2019 article is evident from the more than 25 citations it has accumulated in studies of wildlife, stream health, adaptive environmental management, erosion, and other fields, only two years since publication. The second document is a multi-agency report detailing restoration best practices in the sagebrush biome of the western United States, which stretches from Washington State, down through the Great Basin, and across to the Dakotas and northern New Mexico. Ecological degradation in this vast area has affected more than 350 plant and animal species. These two documents represent a new and invaluable resource for land managers, stakeholders, policymakers, and the research community.

Review Publications
Bowman-Prideaux, C., Newingham, B.A., Strand, E.K. 2021. The effect of seeding treatments and climate on fire regimes in Wyoming sagebrush steppe. Fire. 4(2). Article 16. https://doi.org/10.3390/fire4020016.
Hammond, D.H., Strand, E.K., Hudak, A.T., Newingham, B.A. 2019. Boreal forest vegetation and fuel conditions 12 years after the 2004 Taylor Complex fires in Alaska, USA. Fire Ecology. 15(32):1-19. https://doi.org/10.1186/s42408-019-0049-5.
Germino, M., Brunson, M., Chambers, J., Epanchinj-Niell, R., Fuller, G., Hanser, S., Hardegree, S.P., Johnson, T., Newingham, B.A., Pellant, M., Sheridan, C., Tull, J. 2021. Chapter R. Restoration. In: Remington, T.E., Deibert, P.A., Hanser, S.E., Davis, D.M., Robb, L.A., and Welty, J.L., editors. Sagebrush conservation strategy: Challenges to sagebrush conservation. Fort Collins, CO: U.S. Geological Survey. p. 203-221. https://doi.org/10.3133/ofr20201125.
Karpicka-Ignatowska, K., Laska, A., Rector, B.G., Skoracka, A., Kuczynski, L. 2021. Temperature-dependent development and survival of an invasive genotype of wheat curl mite, aceria tosichella. Scientific Reports. 83:513–525. https://doi.org/10.1007/s10493-021-00602-w.
Kuczynski, L., Radwanska, A., Karpcika-Ignatowsak, K., Laska, A., Lewandowski, M., Rector, B.G., Majer, A., Raubic, J., Skoracka, A. 2020. A comprehensive and cost-effective approach for investigating passive dispersal in minute invertebrates with case studies of phytophagous eriophyid mites. Methods in Ecology and Evolution. 82:17–31. https://doi.org/10.1007/s10493-020-00532-z.
Weltz, M.A., Huang, C., Newingham, B.A., Tatarko, J., Nouwakpo, S.K., Tsegaye, T.D. 2020. A strategic plan for future USDA- Agricultural Research Service erosion research and model development. Journal of Soil and Water Conservation. 75(6):137A-143A. https://doi.org/10.2489/jswc.2020.0805A.
Blank, R.R., Clements, D.D., Morgan, T., Harmon, D.N., Allen, F.L. 2020. Suppression of cheatgrass by perennial bunchgrasses. Rangeland Ecology and Management. 73(6):766-771. https://doi.org/10.1016/j.rama.2020.04.004.
Fullhart, A.T., Nearing, M.A., McGehee, R., Weltz, M.A. 2020. Temporally downscaling a precipitation intensity factor for soil erosion modeling using the NOAA-ASOS weather station network. Catena. 194. Article 14709. https://doi.org/10.1016/j.catena.2020.104709.