Creating a Weed Early Warning System for Idaho’s Rangelands

The Challenge:

When invasive plants spread across landscapes, they alter the function of plant communities, diminishing our natural heritage and negatively affecting rural economies. The longer an invasive species goes undetected and untreated, the more difficult and expensive it becomes to control. As invasive plants multiply, they take an increasing toll on range productivity, watershed health, wildlife habitat and land management budgets. However, across Idaho’s vast rangelands, it is not possible to scout every acre every year in search of new invaders. How can we detect infestations when they are small and manageable?

Our Response:

U of I researchers have pioneered methods to understand factors that make plant communities susceptible to invasion. We are implementing these methods through a series of online maps that detail areas that are susceptible to invasion by specific weedy/invasive species. Now, a new approach we are testing is to look at areas that are susceptible to invasion by multiple plant species. That is, are there more non-native plant species in areas where several invasive species susceptibility maps overlap? Do areas of map overlap have more non-native species when those areas are adjacent to roads?

Working at Rinker Rock Creek Ranch in south-central Idaho, we have created maps showing where up to seven invasive plant species overlap in their potential to invade. We are sampling the plant communities across gradients from areas of no species overlap (not susceptible to invasion) to areas where two to seven susceptibility maps overlap. The sampling will occur in areas away from roads and adjacent to roads. We record plant cover by species in each area, noting which plants are native and which are not native. We are looking for a relationship between the number of overlapping maps and the diversity of non-native species. If this susceptible site mapping approach works at Rinker Rock Creek Ranch, we can provide other land owners and managers with a new tool for early detection of invasive species by focusing on the most susceptible sites.

Output and Outcomes:

• Develop a tool to help landowners and land managers set up detection sites to watch for newly invading plant species. 
• Detect and treat new invasions early when the problem is small and manageable, rather than dealing with bigger, more expensive problems after invasive plants become established. 
• Limit the economic and ecological losses posed by invasive plant species. 

Center Members Involved:

• Tim Prather — Invasive Plant Biology
• Lisa Jones — Invasive Plant Biology

Sponsors and Partners

• The Nature Conservancy — Idaho 
• Wood River Land Trust