Setting and implementing regional strategies for landscape-scale invasive plant management

Detecting and responding to invasive plant populations before they spread is the most effective way of limiting their impact, but prioritizing invasive plant populations at the landscape scale is challenging. Working with public and private land managers, Cal-IPC developed a transparent process to set regional priorities for invasive plant management. The process is being used by seven multi-county regions in California (comprising 30 of the state’s 58 counties) to set early eradication priorities. More than 40 organizations are significantly involved in collaborative regional planning through this process.

Our approach uses spatial distribution data from the online decision-support tool CalWeedMapper (calweedmapper.cal-ipc.org). CalWeed Mapper contains statewide maps of the 210 species in the California Invasive Plant Inventory developed through expert knowledge and compiled GIS datasets. Mid-century projections of suitable range (based on 17 GCMs) are provided for 69 species. CalWeedMapper also records whether populations are spreading and if they are under management.

The Northwest California region, comprising two counties that span from the Cascade mountains to the Pacific Ocean, is one of those currently developing funding proposals. This project will focus on region-wide eradication of knotweed (Fallopia spp.) and several other invasive plant species that are not yet widespread in the region.  The 5-year project budget will be in the $1M range, a scale that is only possible because this mapping and prioritization approach provides funding agencies (such as California’s Wildlife Conservation Board) with a strong transparent rationale for eradicating these populations before they spread and have much greater ecological impact.