Flat Tops Ecological Conservation: Mapping Yellow Toadflax to Inform Invasive Species Management within the Flat Tops Wilderness

Yellow toadflax (Linaria vulgaris) is an invasive perennial plant that is harmful to the biodiversity and function of the North American ecosystems it invades. Yellow toadflax thrives in subalpine zones, reducing forage for grazing animals and outcompeting native species. We partnered with the Yampa Ranger District of the U.S. Forest Service (USFS), which aims to maintain the native biodiversity of western Colorado’s Flat Tops Wilderness Area. Our partners at the USFS have been manually treating and tracking yellow toadflax expansions in and around the Flat Tops Wilderness for the past 20 years. We aimed to develop spatial predictions of suitable habitat of yellow toadflax and evaluate the ability to detect existing populations to aid the USFS in their conservation efforts. We created a habitat suitability model which used field data points and several topographic and remote sensing variables to run three different machine-learning models. We also created a phenology time series plot across the 2024 growing season using field data from the partners, as well as Landsat 8 and Landsat 9 satellite imagery. This informed the species detection model, which sought to identify current yellow toadflax invasions. Results from the detection model, which included dates selected from the phenological time series plot, yielded no statistically viable results. This demonstrated the limitations of using remotely sensed imagery to map current outbreaks of yellow toadflax. The suitability model, on the other hand, produced viable habitat prediction maps aligned with expectations, which may help our partners save resources by narrowing down potential areas of concern for invasive species management.