Location: Pest Management Research
2018 Annual Report
Objectives
Objective 1: Identify and bridge critical knowledge gaps in the taxonomy, native origin, population structure, and reproductive strategies of key invasive weeds, as necessary to support the successful development of classical biological control programs. [NP304, Component 1, Problem Statements 1A, 1B, and 1C; Component 2, Problem Statement 2B2]
Subobjective 1.A: Determine the correct taxonomy and extent of hybridization of invasive weeds.
Subobjective 1.B: Determine the origins, population structure and reproductive mode of invasive weeds.
Objective 2: Develop novel, effective biological weed control and rangeland restoration methods that synergize ecological interactions, such as herbivory, weed population heterogeneity, invasion-dynamics, competition between weeds and native vegetation, and plant-soil interactions. [NP304, Component 2, Problem Statements 2B2, 2B3 and 2B4]
Subobjective 2.A: Understand insect community composition and assembly in response to restoration and prior to the release of Russian olive biological control.
Subobjective 2.B: Determine plant population, community and soil characteristics that contribute to the control of invasions.
Approach
Weeds in pastures and croplands in the U.S. result in billions of dollars per year in lost production and control costs. The goal of our project is to decrease weed abundance by increasing the efficacy of biological control agent development and improving the establishment success of plant community restorations that resist invasion. Our team’s research spans multiple aspects of weed control, from the taxonomy required for effective development of weed management strategies, demographic and ecological research to optimize biological control management efficacy, and identification of the inputs required in restoration that support productive invasion-resistant landscapes. We will address critical gaps in genotype-specific information regarding the reproductive strategies, origin and invasiveness of some of the most important invasive weeds in the U.S., thus guiding effective control methods including effective biological control agents. We will identify ecological, demographic, and biological factors limiting invasion potential for weeds with different life histories. This will generate strategies that limit the spread of target weeds and provide a general framework of biologically- and ecologically-based weed control methods. We will also create realistic targets for restoration that benefit landscapes. This work develops science-based, economical weed management that reduces costs, promotes food security and minimizes negative environmental impacts of weed control.
We focus on rangeland weeds in the Northern Great Plains and extend this research nationally across a range of habitats. By communicating our results through on-going relationships with land management agencies, farmers and ranchers, academic societies, industry and state extension services, this research supports innovative strategies vital to the sustainability and health of U.S. agroecosystems.
Progress Report
Objective 1: ARS scientists in Sidney, Montana continued DNA collections of critical invasive species in the western U.S. and from their putative origins in Eurasia, including Russian knapweed, leafy spurge, dyers woad, mullein and flowering rush. They are now using molecular markers to determine the correct invasive species identification, major mode of reproduction, as well as specific origin of these invasions. In addition, genetic information is being used to inform researchers and land managers if an invasion in one region of the U.S. is genetically similar to the same species invasion in a different region of the U.S. This information is being used to develop more effective foreign biological control agents to fight against invasive plants in the U.S.
Objective 2: ARS researchers in Sidney, Montana have also collected pilot data on whitetop population structure versus habitat conditions and established a long-term (5 year) whitetop common garden designed to understand variability in clonality vs. seed production among populations, and importance of insect herbivory to plant growth and reproduction rates.
Two papers on energy development and restoration impacts to plants, soils and insects are written, one (plant-soil linkages) is being revised for resubmission and one (arthropod communities) is being prepared to submit. Data show reclaims have reduced plant cover and more weedy/invasive plants than nearby rangeland, likely because soils remain degraded. Reclaims also have more crop pest grasshoppers, but spiders and soil biota appear to have recovered. These data have identified pitfalls in current reclamation practices that will be targeted with future research. Methods for data collection on plants and soils along the Yellowstone River have been vetted via peer review. Full replication of sites has been established and data collection techniques finalized.
Accomplishments
1. Restoring rangelands in the Bakken oilfields. Energy development is a large driver of land-use change in northern plains rangelands, requiring reclamation to reverse impacts of associated disturbance. Successful reclamation should recover diverse and productive biological communities that support ranching and a variety of ecosystem services, but little has been done to assess whether reclamation practices achieve these goals. ARS researchers in Sidney, Montana compared plants, soil properties, underground organisms, grasshoppers and spiders on reclaimed oil well sites vs. nearby healthy rangelands. They found that reclaim plant communities had more weedy/invasive species, which related to salinity and organic matter levels in reclaim soils, as well as increased numbers of crop pest grasshoppers. These results suggest that addressing soil degradation during reclamation activities will improve the successful recovery of biological communities and maintain low pest insect abundances, findings that will help ranchers and land managers improve the productivity of rangeland plant communities and limit potential outbreaks of crop pests.
2. Meta-analysis determines the role of hybridization in tree invasions. Invasive tree species are a growing ecological concern worldwide, yet we know little about how hybridization affects their invasive success and thus have little predictive power about how to best prevent future tree invasions. ARS researchers at Sidney, Montana performed an analysis of all known hybrid tree invasions world-wide, and determined patterns in abundance of hybrid trees, hybrid characteristics that enhance invasions, the role of native plant species in invasive tree hybridization, and how important intentional tree hybridization and intentional vs. accidental introduction are in contributing to invasion. The analysis was presented in a special publication issue “Tree invasions: towards a better understanding of their complex evolutionary dynamics” created by an international team, and provides a comprehensive overview of the factors that promote and mitigate the invasive success of tree species in many parts of the world.
3. Invasive plants spread in different ways depending on soil type and plant community. Effective control of plant invasions requires knowing how plant species spread. ARS researchers at Sidney, Montana compared the relative amount of seed versus clonal underground root propagation within different populations of whitetop (Lepidium draba) along the North Platte River in Colorado. They discovered that populations vary in how much seed production contributes to population expansion and invasion within sites, and that this variation may be associated with differences in soil conditions and vegetation cover. This information is crucial to land managers and ranchers for optimizing weed control and biocontrol targets, as it suggests the best weed life stage for management might be different under various habitat conditions.
4. Invasive Russian olive removal improves insect communities. We often do not know how invasive plant removal, especially large, dominant, invasive trees affects creating desired habitats. ARS researchers from Sidney and Miles City, Montana have established a long-term monitoring project on the effects of Russian olive (Eleagnus angustifolia) removal and subsequent restoration on associated plant and insect communities along the ecologically and economically important Yellowstone River. Initial findings suggest arthropod communities have shifted in the short term; removal plots have increases in both plant-feeders and predators, such as spiders, and have more variability in species compared to the adjacent Russian olive plots. Few detailed long-term datasets are available to test how and if weed removal affects organisms other than plants. This project is providing vital information on how weed invasion management can improve habitats for hunters, ranchers and native wildlife.
5. Massive seed banks limit Russian olive control. ARS researchers from Sidney and Miles City Montana determined additional successful practices for controlling invasive Russian olive populations and returning native species to these degraded areas. Because Russian olive is a nitrogen fixer, we expected high weed abundance to limit the success of planted native species (i.e. revegetation) in this nitrogen altered ecosystem, however revegetation was successful: almost all planted species established. While revegetation increased native species diversity and cover, there was no evidence that the plantings served to competitively exclude weeds in this five-year study. Huge variation in newly emerged Russian olive seedlings (approximately 50-5000 seedlings per acre) in the years after removal indicates that understanding seed banks of this species is critical to its control. Successful eradication of this species requires revisiting removal sites yearly, but is otherwise a small time commitment because seedlings are very easy to hand-pull and chemical control is required only for resprouts from Russian olive stumps.
Review Publications
West, N.M., Louda, S.M. 2017. Cumulative herbivory outpaces compensation for early floral damage on a monocarpic perennial thistle. Oecologia. 186(2):495-506. https://doi.org/10.1007/s00442-017-4027-9.
Espeland, E.K., Perkins, L. 2017. Weed establishment and persistence after water pipeline installation and reclamation in the mixed grass prairie of western North Dakota. Ecological Restoration. 35(4):305-310.
Espeland, E.K., Hendrickson, J.R., Toledo, D.N., West, N.M., Rand, T.A. 2017. Soils determine early revegetation establishment with and without cover crops in northern mixed grass prairie after energy development. Ecological Restoration. 35(4):311-319.
Espeland, E.K., Muscha, J.M., Scianna, J., Kilian, R., West, N.M., Petersen, M.K. 2017. Secondary invasion and re-invasion after Russian-olive removal and revegetation. Invasive Plant Science and Management. 10:340-349. https://doi.org/10.1017/inp.2017.36.
Schantz, M., Espeland, E.K., Duke, S.E. 2017. Measuring succession: methods for establishing long term vegetation monitoring sites. Plant Ecology. 218(10):1201-1212. https://doi.org/10.1007/s11258-017-0761-7.
Endres, A., West, N.M., Evans, J.A., Schlessinger, L. 2017. Data driven weed management: Tracking herbicide resistance at the landscape scale. In: Kraska, J., Honaker, B., Macy, M., Spencer-Kuhlmann, L., Williams, N., Mantell, S., Harris, T., Hemme, M., editors. Agricultural Law Symposium, Plowing New Ground: The Intersection of Technology and Agricultural Law. Little Rock, AR: University of Arkansas at Little Rock Law Review. p. 425-436.
Gaskin, J.F., Shwarzlaender, M., Gibson, R., Simpson, H., Marshall, D.L., Gerber, E., Hinz, H. 2018. Geographic population structure in an outcrossing plant invasion after centuries of cultivation and recent founding events. AoB Plants. 10(2):ply020. https://doi.org/10.1093/aobpla/ply020.
Espeland, E.K., Kettenring, K. 2018. Strategic plant choices can alleviate climate change impacts: a review. Journal of Environmental Management. 222:316-324. https://doi.org/10.1016/j.jenvman.2018.05.042.
Espeland, E.K., Johnson, R.C., Horning, M.E. 2018. Plasticity in native perennial grass populations: Implications for restoration. Evolutionary Applications. 11(3):340–349. https://doi.org/10.1111/eva.12560.
Lee, S., Gaskin, J.F., Kim, Y. 2018. Molecular diagnosis for a Tamarix species from two reclaimed lands along the Yellow Sea in Korea inferred from genome wide SNP markers. Journal of Systematics and Evolution. https://doi.org/10.1111/jse.12432.
