ISSUES
• Outcompeting invasive weeds.
• 2:1 to 1:1 steep slope.
• 5” rain event two days after install.
PROBLEM
Bohemian Knotweed is an invasive species that can take over an area, choking out existing vegetation and leading to erosion as the better suited species are displaced. Such was the case in Cordova Alaska, situated on the southeastern end of Prince William Sound. Eradicating the knotweed and establishing desired vegetation quickly was necessary to halt the advance of the destructive knotweed and restore the area.
SOLUTION
The Plant Materials Center was contacted to create a solution that would meet the restoration and eradication goals. Casey L. Dinkel and Phil Czapla designed a seed mix custom tailored for the unique micro climate found in the project location.
Seeding Mixture: Application rate of 1.5 lbs per 1000sq/ft
• Arctagrostis latifolia – Polargrass – 60%
• Deschampsia cespitosa – Tufted Hairgrass – 25%
• Festuca rubra – Red Fescue – 10%
• Lolium multi orum – Annual – 5%
A slow release organic fertilizer with a 25% turkey manure base was also used to ensure the plants established quickly in preparation for the long winter.
RESULTS
After removing the knotweed and installing rock to drain the naturally occurring seeps, the slopes were re-contoured to a 1:1 – 2:1 finish grade. Biotic Earth was applied at a rate of 3000lbs per acre and then covered with a bonded fiber mulch to ensure the seed, fertilizer, and Biotic Earth were kept in place during erosive rain events. The design was tested by Mother Nature within 48 hours by over five inches of rainfall over a two day period. With no impact to the installation, the successful eradication and restoration is well under way. The long term nutrient cycling provided the Verdyol Biotic Earth will be fundamental is supporting the desired species and preventing the re-emergence of the invasive knotweed.
