Susceptibility of Montgomery Park Trees to Emerging Invasive Pests

Abstract

This report provides recommendations to the Montgomery County Department of Parks on the management of four invasive pests: Asian longhorned beetle (Anoplophora glabripennis), spotted lanternfly (Lycorma delicatula), oak wilt, and thousand cankers disease in managed park regions. To prepare for these potential infestations, an analysis of the risk to current park tree populations was performed using unique spatial and tree data characteristics. Additionally, a comprehensive interactive toolkit that provides park staff with information on best management practices was developed. To evaluate risk of each pest, literature was reviewed to identify host species, relevant life history traits, and possible management strategies applicable to Montgomery Parks. The host species for each pest was then overlaid with a list of managed trees species to identify host species important for the final recommendations. Pest characteristics were considered when developing pest specific management strategies. General information on increasing park resiliency was also explored to propose the most effective management strategies. To produce meaningful pest risk values for each park, a novel risk equation was designed using an array of current pest risk assessments. It utilizes a parameter of diversity, representing ecosystem resiliency, as well as a weighted measure of the host species’ biomass available to each pest. The final risk values are then incorporated into ArcGIS to generate risk maps for the county. The intended function of the ArcGIS web application is to provide the Montgomery County Department of Parks management staff and administration with a detailed tree inventory analysis. The module is equipped with a mapped tree inventory complete with park statistics such as diversity, total tree count, species distribution and a risk value for each pest of concern. This tree inventory can be viewed on a spatial scale, allowing for visual representation of park and tree data across the county within various environmental management regions. The data is also intended to model risk susceptibility for four invasive pests within the region. This data can assist Park staff with mitigation planning and in developing an effective response to a spread of these specific pests. While it is intended for professional use, other functions can be added for public access to report potential sightings and include general information about invasive pests in urban parks. To inform future management actions, potential ecosystem services lost for each high risk host species were calculated. Results assigned a monetary value for each tree species based on mean tree characteristics provided by the Parks department. A general benefit evaluation of all the trees inventoried in Montgomery County parks was also generated using the iTree database.