Research Project: Development of Management Strategies for Livestock Grazing, Disturbance and Climate Variation for the Northern Plains

Location: Livestock and Range Research Laboratory

2021 Annual Report

Objectives
Objective 1: Develop management strategies to improve rangeland cattle production and ecological stability through effective use of rangeland forage and supplementation. Subobjective 1A: Determine effects of dormant rangeland forage utilization on heifer development, young cow productivity, plant productivity, and species composition. Subobjective 1B: Determine effects of seasonal rangeland forage utilization by steers and heifers during backgrounding on estimates of respiration gas. Subobjective 1C: Determine timing of grazing season and grazing intensity effects on plant productivity, community composition and cattle diet quality. Subobjective 1D: Enhance the accuracy of DNA metabarcoding to assess diet composition. Subobjective 1E: Evaluate factors regulating calf growth on rangelands. Subobjective 1F: Use precision management technologies (global positioning of livestock, sensor networks, virtual fencing, remote sensing of landscape and others) to enhance livestock producer capability for optimum management of pastures and rangelands, allowing balance between production and ecosystem services. Objective 2: Develop management techniques to improve stock water quality in reservoirs by manipulating plant and microbiota abundance. Objective 3: Develop management strategies to restore degraded rangelands and prevent weed invasions. Subobjective 3A: Develop bacterial management strategies to reduce invasive bromes. Subobjective 3B: Improve vegetation outcomes on Conservation Reserve Program lands. Subobjective 3C: Design seed mixes to more consistently meet plant establishment goals during rangeland restoration. Subobjective 3D: Identify seasonal grazing effects on revegetation following Russian olive removal. Objective 4: Identify cool-season perennial grass seed rates that are high enough to prevent weed invasions and low enough to allow establishment of diverse plant communities on disturbed rangelands. Subobjective 4A: Identify cool-season grass seed rates needed to prevent weed invasions and allow seeded shrub establishment during rangeland restoration. Objective 5: Determine the effect of subsurface soil calcium carbonate on available phosphorus, plant biomass, root traits, and mycorrhizal responsiveness. Objective 6: Develop fire management strategies to maintain and improve rangeland stability and livestock production. Subobjective 6A: Determine perennial grass response to timing of fire relative to plant phenology. Subobjective 6B: Quantify drought and post-drought fire effects on plant community composition and productivity. Subobjective 6C: Determine how seasonal timing of fire affects forage quality and cattle grazing preference.

Approach
Sustainability of rangeland production hinges on the ability of plant communities to resist change and quickly recover from disturbance (stability) because changes in species composition, forage production, and forage quality fundamentally affect the animal community. Primary forces of change in rangelands are weather, grazing, alien plants, fire and their interactions. This project is designed to improve ecological sustainability and rangeland production by addressing opportunities for increased efficiency of livestock nutrient conversion, mechanisms affecting restoration success and weed control, and interacting effects of management with weather. Improved efficiency of nutrient conversion from dormant rangeland forages is among the most viable options for increasing animal production and minimizing effects on plant communities. We will address this proposition through a series of experiments evaluating plant and animal responses to dormant-season utilization and supplementation strategies. Rangeland restoration methods will be evaluated for direct weed control and mechanisms controlling successful establishment of desirable species. Water manipulations and historical weather data will be included in experiments to determine weather and long-term climate effects on plants and livestock because precipitation is the primary controlling factor for plant productivity and community composition. Fire research will focus on timing of fire (seasonal and phenological) to facilitate development of fire prescriptions that reduce weedy species, promote desirable species, and increase availability of quality forage. Scientists will be integrated across objectives to determine interacting effects of precipitation, grazing, weeds, and fire on soil and plant communities (production, species composition, diversity, propagation, survival) and cattle (weight gain, reproductive performance, diet quality, diet selection). Understanding mechanisms that control rangeland stability and animal responses to alterations in plant communities will assist land managers and livestock producers in improving rangeland integrity (diverse communities dominated by native species) and efficiency of livestock production. Results will also provide scientists greater understanding of the complex interacting forces on rangelands.

Progress Report
Objective 1A: Data were collected on individual animal supplement intake, animal productivity, plant productivity and species composition. Animal use of feeders was good and high percentages of animals were recorded. Objective 1B: Through two trial years, animals did not train well to the specialized feeder required for gas samples. A redesign was attempted, but no animals were available to conduct the study. Objective 1C: Vegetation samples were collected and growing season grazing treatments and diet samples were completed. Fall 2020 treatments and collections were conducted and are on schedule. Objective 1D: Lab time has been limited by COVID-19-related restrictions, which has delayed polymerase chain reaction analyses. Objective 1E: Analyses describing trends in birth date effects on animal performance has been completed. Objective 2: We completed our study of artificial floating islands as a tool to improve livestock drinking water. Given the small amount of sulfur removed (per plant) relative to the vast amount of dissolved sulfate possible in rangeland water sources, planted artificial floating islands are not likely to be a practical tool for reducing sulfate in livestock drinking water. Conversely, water treatment systems may be justified in some cases. Objective 3A: The weed-suppressive bacteria study on annual bromes is complete. Findings indicate that the ACK55 and D7 strains of Pseudomonas fluorescens are not reliable tools for controlling Bromus tectorum in the northern Great Plains and Central Rocky Mountains. Objective 3B: The final data have been gathered for the Conservation Reserve Program project. Objective 3C: Final data were collected to evaluate seed mixes in rangeland restoration. Objective 3D: A new research site is being prepared due to periodically poor accessibility to the initial research site. Supporting research in the interim determined that fire provides effective control of Russian olive seeds and seedlings. Objective 4: Final data were collected to determine cool-season grass seeding rate effects on seeded shrub establishment. Objective 5: A second round of mycorrhizal trap cultures yielded mycorrhizal morphotypes which are currently being amplified for the experiment. A recommended heat treatment failed to eliminate mycorrhizal fungi. A second heating trial is being conducted to test a broader range of temperatures. The mycorrhizal culturing and soil heat treatments have delayed the start of the experiment to determine effects of soil calcium carbonate on available phosphorus, plant production, and mycorrhizal responsiveness. Objective 6A: COVID-19 restrictions prevented greenhouse growth of experimental plants by our collaborator. Plans will progress on a delayed schedule to assess plant phenology effects on plant response to fire. Objective 6B: Drought treatments have been completed and plant responses have been measured. Final post-drought fire treatments are scheduled for this summer, but the region is currently under burn restrictions. Objective 6C: Fire seasonality treatments were applied, and grazing selection trials are continuing. Plots are prepared for another cycle of fire treatments on another site.

Accomplishments
1. Plant-soil feedbacks and plant abundance. A long-standing challenge in the field of ecology is to reveal which factors regulate plant abundance, coexistence, and community composition. Plants often accumulate soil biota which have host-specific negative impacts and may strongly affect plant performance and mixtures of vegetation. Such plant-soil feedbacks have been widely studied, but results vary by study on their relationship with plant species abundance in the field. ARS researchers in Miles City, Montana, in collaboration with researchers from nine countries, conducted a synthesis of experiments from tropical forest to semiarid grasslands. Across experiments, results indicate a tendency for a positive correlation between plant field abundance and feedback across plant functional types and variation by functional type. The results provide quantitative support that plant abundance has a general, albeit weak, positive relationship with plant-soil feedback across ecosystems thereby suggesting harmful soil biota tend to accumulate around and disproportionately impact rare plants more than abundant plants.

2. Water quality for livestock in northern Great Plains rangelands. High concentrations of sulfates and other dissolved solids in water sicken livestock and can reduce feed efficiency and growth, but ranchers’ efforts to detect and manage water quality issues are complicated because water quality varies widely across rangelands. To improve water quality predictions in the northern Great Plains, ARS researchers in Miles City, Montana, measured and modeled concentrations of dissolved solids at 45 locations for 11 years, noting that calcium, fluoride, magnesium, sodium, and total dissolved solids sometimes exceeded levels recommended by published water quality guidelines, but rarely or never reached levels shown to negatively impact livestock. Iron often attained concentrations known to reduce water consumption and was most likely to be elevated in creeks and reservoirs, whereas fluoride was most likely to be elevated in wells. Sulfate occasionally reached concentrations shown to reduce weight gain, and in a few instances achieved concentrations associated with severe health problems, but excessive sulfate was less likely in reservoirs. In high precipitation years, dissolved solids tended to increase in creeks and decrease in reservoirs. One safeguard against water quality problems is ensuring livestock can access multiple water sources of different types, such as wells and reservoirs, and where this is impossible, electrical conductivity meters can provide ranchers rough estimates of water quality to identify watering locations requiring avoidance or detailed monitoring.

3. Mycorrhizal fungi and crested wheatgrass. The invasive crested wheatgrass covers more than 10.5 million ha in North America and such invasive plants may alter arbuscular mycorrhizal fungi communities on which resident plants depend. ARS researchers in Miles City, Montana, tested whether the invader crested wheatgrass associates with different mycorrhizal fungi than resident plants. The study compared mycorrhizal communities of six crested wheatgrass-dominated sites to five sagebrush steppe and three mixed-grass prairie sites in the northern Great Plains. Roots of crested wheatgrass were without arbuscular mycorrhizal fungi and supported fewer types of mycorrhizal fungi than seven native species and two non-native species. Restoring natives to crested wheatgrass-dominated rangeland is notoriously difficult. These findings suggest a lack of soil mutualists may contribute to restoration difficulty.

4. Fire and herbicide reduce annual bromes. Wide-spread invasive annual grasses, cheatgrass and Japanese brome, have sudden population increases and compete with native species. ARS scientists in Miles City, Montana, tested the individual and combined effects of fall fire (no fire; fall fire with 2-year return interval) and the herbicide aminopyralid (no herbicide; alternate-year herbicide; annual herbicide) on annual brome control. Fire reduced brome biomass 78% for one or two growing seasons after fire and biomass of all species except brome was 19% greater with fire during two years, but fire did not affect percent germination of new brome seed. Herbicide reduced brome germination each year it was applied but did not affect brome biomass. Complementary treatment combinations could increase control if they address different phases of the brome life cycle. However, the combination of fall fire and spring application of aminopyralid did not extend annual brome control under the study conditions and long-term control of annual bromes will require long-term commitment to repeated treatment.

5. Annual bromes decrease with increasing fall defoliation intensity. Invasion of Japanese brome into rangelands has increased during recent decades with negative consequences for native plant communities and livestock production. Japanese brome is positively correlated with plant litter and standing dead material, so ARS researchers in Miles City, Montana, quantified the effects of manipulating those components with fall defoliation at four different mowing heights (10, 6, 4, or 1 cm) compared to a non-mowed control across four years. Mowing to 1 cm reduced brome biomass by 40% compared to non-mowed plots and brome production was highly dependent on September-October precipitation. Spring soil water was not reduced by fall mowing and non-brome biomass was similar across treatments. Perennial grass basal cover was similar for 10, 6, and 4 cm mowing heights and greater than that for mowing at 1 cm whereas, no differences were detected between non-mowed plots and any mowing height. Increasing fall defoliation intensity reduced annual bromes while allowing perennial grasses to persist, indicating fall mowing and possibly grazing are viable options for livestock producers, land managers and conservationists to manage annual bromes.

Review Publications
Waterman, R.C., Vermeire, L.T., Reinhart, K.O., Rinella, M.J. 2021. Influence of grazing season, residual herbage, and precipitation on rumen extrusa diet quality. Rangeland Ecology and Management. 78:117-126. https://doi.org/10.1016/j.rama.2021.06.004.
Waterman, R.C., Vermeire, L.T. 2021. Annual bromes decrease with increasing fall defoliation intensity. Global Ecology and Conservation. 28. Article e01652. https://doi.org/10.1016/j.gecco.2021.e01652.
Vermeire, L.T., Rinella, M.J., Strong, D.J. 2021. Individual and combined effects of fall fire and growth-regulator herbicide on annual bromes. Rangeland Ecology and Management. 76:129–138. https://doi.org/10.1016/j.rama.2021.02.009.
Reinhart, K.O., Carlson, C.H., Feris, K.P., Germino, M.J., Jandreau, C.J., Lazarus, B.E., Mangold, J., Pellatz, D.W., Ramsey, P., Rinella, M.J., Valliant, M. 2020. Synthesis of weed-suppressive bacteria studies in rangelands of the western United States: Special section of articles in Rangeland Ecology & Management provides little evidence of effectiveness. Rangeland Ecology and Management. 73(6):737-740. https://doi.org/10.1016/j.rama.2020.02.007.
Christie, A.P., Amano, T., Martin, P.A., Abecasis, D., Adjeroud, M., Anton, A., Baldigo, B.P., Barrientos, R., Bicknell, J.E., Rinella, M.J. 2020. Quantifying and addressing the prevalence and bias of study designs in the environmental and social sciences. Nature Communications. 11. Article 6377. https://doi.org/10.1038/s41467-020-20142-y.
Progar, R.A., Fettig, C.J., Munson, S.A., Mortenson, L.A., Snyder, C.L., Kegley, S.J., Cluck, D.R., Steed, B.E., Mafra-Neto, A., Rinella, M.J. 2021. Comparisons of efficiency of two formulations of verbenone (4, 6, 6-trimethylbicyclo [3.1.1] hept-3-e3n-2-one) for protecting whitebark pine (Pinus albicaulis) from mountain pine beetle (Dendroctonus ponderosae). Journal of Economic Entomology. 114(1):209–214. https://doi.org/10.1093/jee/toaa289.
Reinhart, K.O., Vermeire, L.T. 2021. Importance of phytobiomass and ungulates to hydrologic function in a temperate grassland. Rangeland Ecology and Management. 78:1-4. https://doi.org/10.1016/j.rama.2021.04.009.
Reinhart, K.O., Williams, A., Vermeire, L.T. 2020. Effects of defoliation, litter, and moss on Bromus arvensis in a northern mixed-grass prairie. Rangeland Ecology and Management. 73(5):607-610. https://doi.org/10.1016/j.rama.2020.06.005.
Rinella, M.J., Muscha, J.M., Reinhart, K.O., Petersen, M.K. 2020. Water quality for livestock in northern great plains rangelands. Rangeland Ecology and Management. 75:29-34. https://doi.org/10.1016/j.rama.2020.11.005.
Reinhart, K.O., Rinella, M.J. 2020. Molecular evidence for impoverished mycorrhizal communities of Agropyron cristatum compared with nine other plant species in the Northern Great Plains. Rangeland Ecology and Management. 74:147-150. https://doi.org/10.1016/j.rama.2020.08.005.
Reinhart, K.O., Bauer, J.T., Mccarthy-Neumann, S., Macdougall, A.S., Hierro, J.L., Chiuffo, M.C., Mangan, S.A., Heinze, J., Bergmann, J., Joshi, J., Duncan, R.P., Diez, J.M., Kardol, P., Rutten, G., Fischer, M., Van Der Putten, W.H., Martijn Bezemer, T., Klironomos, J. 2021. Globally, plant-soil feedbacks are weak predictors of plant abundance. Ecology and Evolution. 11(4):1756-1768. https://doi.org/10.1002/ece3.7167.