In 2013, NCF’s Science and Stewardship Department started down the road of a wetland restoration project in Madequecham Valley that at the time seemed incredibly daunting. We idealistically set out to eradicate a 0.6 acre patch of an incredibly invasive plant, Phragmites australis, the common reed.
Phragmites australis is a large, perennial grass, that has become a common invasive species in freshwater and brackish wetlands across North America. The impacts of the Phragmites on aquatic ecosystems include modifying wildlife habitat, reducing plant diversity, and altering abiotic factors of the environment. It often outcompetes the growth of native plants by forming thick root mats and large, dense aerial shoots. Getting after a Phragmites invasion in the early stages of establishment gives land managers the best shot at eradicating this species before it becomes widespread, with minimal use of herbicide. Left unchecked, future hopes of eradication become increasingly difficult, require more aggressive use of herbicide and sometimes become logistically and/or financially unfeasible.
On Nantucket, extensive monocultural stands of Phragmites exist along the edges of Hummock and Long Pond and many smaller patches are found in wetlands across the Island. The patch at Madequecham was extremely dense and the flowering stems were more than 2.5 meters tall. While the area surrounding this patch contained many native wetland species, the Phragmites patch itself was a complete monoculture that was steadily growing and outcompeting native species. In our pre-treatment plant surveys in Madequecham, we did not document a single other plant species growing within the patch. Given the steady outward growth of this patch, we knew we would eventually lose much of the native diversity in the Madequecham wetland basin if we didn’t contain its spread quickly.
Unfortunately, options are limited when it comes to effectively managing this tenacious plant. Digging, pulling, dredging or burning are rarely viable, effective options and certainly not in this location, but we were also not willing to spray herbicide though that would have been the quickest, and probably most cost effective method in the long term. Instead, we opted for the incredibly labor intensive, but extremely effective method of clip and drip herbicide application. We first bundled stems together using garden twine and then used hedge shears to cut the bundle. We then used a glyphosate-based herbicide solution (without surfactants, but with a purple dye added) to drip herbicide directly in to the stems. This bundle and cut method assures that herbicide stays entirely within the target plant species and greatly increases safety for the applicator.
We began the physical work of treating this patch in 2013 and it took several years of chipping away to work through the entire patch. By 2017, we had significantly reduced the density of Phragmites and started to see native plants recolonizing the area, but we continued to see lots of persistent stems that constantly needed to be re-treated. By opting to continue with just the clip and drip method of herbicide application rather than spraying, we were able to avoid impacting the native species that were beginning to make headway into the patch. Now, 9 years in to this process, we are so incredibly pleased with how the Madequecham Valley wetland is looking. The remaining stems of Phragmites are sparse, short, and non-flowering. Treatment this year required minimal herbicide and only a few hours of our time.
The native plant diversity in the wetland now is amazing. The basin is filled in with saltmarsh fleabane, blue flag iris, swamp milkweed, Marsh St. John’s Wort, swamp rose mallow, boneset, blue vervain, and an assortment of grasses, sedges and rushes.
When you encourage native plant species, it’s not long before you start seeing native wildlife increase in abundance as well! The wetland is now literally abuzz with native insects!
male companion on boneset in the foreground
The reality of waging war on invasive species is that it is rarely a short-term gig – you have to be willing to play the long game. We expect to be returning annually to Madequecham for many more years to follow up and treat individual stems as they come up. Complete eradication is still a ways off but we will get there eventually! Our time investment has been worth it and has decreased significantly from the early days of treatment. We could not be more pleased with the progress and outcome so far.
We have been successful in using clip and drip applications to treat and eradicate other small P. australis patches in other locations across the island including at Folger’s Marsh, Eel Point and West Hummock Pond. We would definitely recommend this technique for land managers with new or very small patches and who want to use minimal amounts of herbicide with low impacts to other plant and animals species in the area. However, we also recognize that treating P. australis in this manner is unrealistic for extensive infestations of this species. In recent years, the Nantucket Pond Coalition has been spear-heading efforts to reduce the enormous stands of Phragmites on Hummock and Long Ponds. This fall, work will begin to reduce the Phragmites on the NCF-owned portions of these ponds. You can read more about these management projects here.
The Nantucket Conservation Foundation is a private, non-profit land trust that depends on contributions from our members to support our science projects, conservation property acquisitions and land management efforts. If you are not already a member, please join us now! www.nantucketconservation.org