Project Overview

Reports

Commodities

Target Pests

Practices

This project proposes to analyze a comprehensive 20-year monitoring and treatment dataset for invasive knotweed (Polygonum spp.) along the Hoh River in western Washington State. Survey and treatment records for knotweed have been collected and systematically maintained since an eradication program was initiated by the Hoh Tribe in 2002, four years after the initial detection of knotweed in the river. The Hoh River is of enormous cultural, social, economic, and ecological importance to the nearby rural and tribal communities, as well as providing relatively pristine habitat for valued fish populations. As such, expansion of invasive knotweed along Hoh River embodies the enormous challenge that invasive plants present for river ecosystems and the people and wildlife that rely on them.

Because the timing and point of introduction of knotweed in the Hoh River is precisely known, and the dataset encompasses information on treatment as well as georeferenced survey data, it represents a unique opportunity for analyses and synthesis that can inform best practices for researchers and managers working on invasive knotweed and other invasive riparian plants. This proposal focuses on two analyses. The first is an analysis of knotweed presence and abundance along the longitudinal river gradient, and how establishment and persistence may be promoted or suppressed over time by environmental characteristics (i.e., environmental filtering). The second will synthesize best practices learned in the course of the 20-year management project, which will strongly support principles of integrated pest management. These best practices will include recommendations of the most effective and safest treatment options, resources required for access and treatment, and robust yet feasible monitoring approaches. We anticipate that the results from both the environmental analysis and the management best practices will offer critical context that can help program managers in other areas that struggle to maintain the long-term support required for successful control and eradication.

Results will be shared through multiple channels to ensure broad reach to researchers, land and natural resource managers, invasive species managers, and private landowners. First will be production and submission of the results as a peer-reviewed manuscript. Second, results and findings will be shared at multiple regional and national conferences. Lastly, the findings will form the basis of a half-day workshop that will be open to practitioners, landowners, and other stakeholders involved in management and control of knotweed. The workshop will focus on the research findings, best practices, and identify priority research gaps with the greatest potential to advance management and treatment for knotweed. The workshop will therefore serve to communicate results, but also strengthen the culture and network of practitioners to carry knotweed research into the future.

Objectives are presented in the order in which they will be implemented. We expect that these objectives can be achieved within the one-year project period. They are:

1. Objective 1 is to analyze the 20-year dataset that has been collected and maintained by 10KYI. This dataset includes monitoring and treatment surveys for invasive knotweed along the Hoh River in 18 survey years between 2001 and 2021 (Figure 1). These data are ready for analysis, which will focus on a) characterizing the longitudinal and temporal patterns of expansion, distribution and persistence and b) the environmental factors that may facilitate or conversely, hinder establishment and persistence of invasive knotweed. 

2.  Objective 2 is to summarize best practices for long-term monitoring and control based on lessons learned over 20 years of treating and monitoring knotweed along the Hoh and other local river systems. These will include description of i) the resources (personnel time and equipment) required for survey and treatment, ii) feasible metrics to monitor populations even at large scales and in remote areas, iii) effectiveness of mechanical and chemical control options, iv) strategies for monitoring as populations decline over time in response to control and v) identification of priority research gaps.

3. Objective 3 is to submit the results as a peer-reviewed publication, which can be used to concisely and succinctly communicate best practices as well as provide context for the long-term effort and focus required for successful control of knotweed and other invasive plants (e.g., Patten et al. 2017). We expect to have a publication in review by the end of the project period, but review and revision times mean that acceptance and publication is very likely to occur after the project period. However, it is possible to submit the work to a journal with expedited review and revision process (e.g., PLOS ONE) should it be necessary to have a manuscript reviewed and accepted within the project period.

4. Objective 4 is communicating the environmental analyses and best management practices to a broad audience that includes researchers, natural resource and land managers, knotweed working groups, and private landowners. The results from the submitted publication will be prepared as conference-style presentations; results from Objectives 1 and 2 can be presented separately or in tandem as appropriate for the venue and audience. To reach the scientific community, we will present the findings at two regional conferences and one national conference. We will also host a virtual half-day knotweed workshop that is focused on presenting these results within the framework of integrated pest management. The workshop will consist of three parts: (i) communicating findings from the environmental analyses, (ii) communicating best practices for monitoring and treatment, and (iii) recommending the priority research gaps where management and monitoring projects can focus and contribute over the next 5-10 years. All local and regional knotweed and invasive species working groups in western states will be invited to attend the virtual workshop.