Clatsop Plains – Long Beach Peninsula Coastal Prairie Restoration

EXECUTIVE SUMMARY
In 2016, treatments varied by site and establishment of seeded species was low across sites. Overall, soil removal treatments showed the most promise across sites. Soil removal plots had lower cover of invasive grasses and forbs and offered more potential management action(s). Future monitoring will help to elucidate treatment effectiveness and aid in management recommendations.
NCLC Sites
Treatments did reduce cover of both exotic forbs and graminoids, in comparison to control plots. Invasive grass species continue to be a concern at all NCLC sites. Native species cover remained relatively low across treatments in 2016. The soil removal treatment had a relatively high ratio of native forbs to invasive forbs, and lower levels of invasive grass cover compared to the other treatments. The lower cover of invasive grasses and forbs in the soil removal treatment provides an opportunity for spot treatment that could reduce competition for seeded species.
Willapa NWR
Invasive grasses and forbs continue to be a management issue at the site. Although the treatments did reduce invasive graminoid cover compared to the controls, all maintained levels that will likely require intensive management. The soil removal and sand addition treatments show the most promise at Willapa NWR. The lack of cover of seeded species is a concern, but the low cover of invasive grasses and forbs is promising and provide opportunities for spot treatment that could reduce competition for seeded species.
Yeon (National Park Service)
This site was very different from the other sites in terms of soil substrate and existing vegetation. The soil removal treatment shows the most promise at Yeon, with higher ratio of native forbs to invasive forbs and lower levels of invasive grass cover compared to the other treatments. While future monitoring will be important to note how this changes in invasive grass cover over time, initial results indicate that current treatments may be excessive for the site and will likely need to be modified.