Location: Pest Management Research
2017 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
This report documents progress for the new research project with start date of 03/15/2017 which continued research from Project 3032-22000-017-00D “Biological Control of Invasive Plants of the Northern Great Plains”.
Objective 1, Invasive plants: ARS scientists in Sidney, Montana continued DNA collections of critical invasive species in the western USA and from their putative origins in Eurasia, including Russian knapweed, dyers woad, mullein and flowering rush. They are now using molecular markers to determine the correct invasive species 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 USA is genetically similar to the same species invasion in a different region of the USA. This information is being used to develop more effective foreign biological control agents to fight against invasive plants in the USA.
Objective 2, Restoration: Ecological data (soils, nematodes, plants, insects) have been collected from oilfield reclamations and adjacent, intact sites. Data analyses of plant, soil, and nematode data are complete. Data extraction from insect samples is complete.
Russian olive: We have identified monitoring sites along the Yellowstone River and have analyzed plant and soil data to ensure adequate replication (N > 3) of site types. One manuscript has been submitted on the long term outcomes of plant restoration after removal. The data demonstrate successful establishment by planted species, and that plantings may increase desirable species cover even beyond original planted areas. We have initiated a collaboration with researchers from Montana State University (MSU) to examine the influence of fluvial morphology and hydrology on Russian olive populations. We are beginning implementation of a long term study on Russian olive seedling recruitment and seed survival in the soil.
Whitetop: We have completed data collection and initial summaries characterizing habitats associated with whitetop infestations, and how the relative importance of seed versus clonal recruitment varies with habitat conditions. This information will enable us to better design studies that target the most effective use of biological control to limit this weed.
For additional information, please see the FY16 annual report for the previous project, 3032-22000-017-00D.
Accomplishments
1. 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; thus we 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, 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.
