With their mission of “Conserving and stewarding Long Island’s natural and historic lands, waters and environmental resources,” LIISMA was lucky enough to hear from Darcy McDowell, representing the North Shore Land Alliance (NSLA), at our Fall Partners Meeting and Workshop. Darcy is the Associate Director of Stewardship and the Native Greenhouse Manager. She shared her team’s challenges and successes with their ever-evolving management of invasive species on multiple properties along the North Shore.
The North Shore Land Alliance, founded in 2003, is a conservation organization dedicated to preserving local ecosystems through various land management and invasive species control projects. They have successfully preserved approximately 1400 acres through environmental bond advocacy, direct property purchases, and conservation easements. With 12 full-time employees, NSLA hosts over 40 environmental education programs annually, engages 100-200 volunteers each year, and manages a summer internship program.
NSLA manages numerous invasive species, with this season including parrot’s feather (Myriophyllum aquaticum) at Williams Pond. Initial approaches involved manual hand pulling by volunteers. With the hopes of gaining better control over the site, NSLA collaborated with the NYS Department of Environmental Conservation to experimentally use a tarp to prevent plant growth by blocking sunlight. Another management effort has been at Cushman Woods, where NSLA has mobilized community forces to manage the aggressive mile-a-minute vine (Persicaria perfoliata), orchestrating group pulling events in observance of New York Invasive Species Awareness Week.
Perhaps most impressive is their comprehensive multi-year management efforts at Humes Preserve, where they’ve used diverse approaches for meadow restoration. In 2016, they employed goat grazing to control porcelain berry, making a dent in the dense vines. Later, they worked with contractors to implement a systematic plan including cover cropping, mechanical clearing, and seeding, followed by targeted broadleaf herbicide applications until 2021.
In 2022, they noticed mugwort (Artemisia vulgaris) had started to become problematic on the property. After attempting to manage the mugwort with selective herbicide application, they decided to go in a different direction. In 2023, The Land Alliance started implementing a selective mowing strategy. In the fall, large monocultures of mugwort are staked and mowed. Then, throughout the growing season, the Land Alliance’s summer interns go out and weed whack any mugwort that regrows. Along with the selective mowing, they have begun using a sheet mulching technique, a method that utilizes cardboard layers beneath 7-8 inches of mulch, they aimed to suffocate mugwort root systems. Preliminary results revealed that March applications of the sheet mulch yield optimal outcomes, when placed in March, the mugwort in the mulched areas had a regrowth rate of less than 10%. Then, in the fall, after these areas of mulch were kept clear of mugwort all summer, 2,000 plugs of native grasses and wildflowers will be planted. Then they will continue to monitor the growth of the native species and the regrowth of the mugwort. They look forward to partnering with Cornell Cooperative Extension to further investigate how much timing affects mugwort survival. Between these two management strategies the mugwort has dramatically reduced from being present in 51% of the meadow in 2022 to just 33% in 2023!
As native species like bluestem (Andropogon scoparium), Indian grass (Sorghastrum nutans), beardtongue (Penstemon), goldenrod (Solidago spp.), and common milkweed (Asclepias syriaca) reclaim their rightful place in the ecosystem, North Shore Land Alliance’s innovative management approaches will hopefully inspire others to undertake similar projects. Their success story demonstrates that with persistent effort, adaptive strategies, experimental thinking, and rigorous monitoring, even a stubborn area can be renewed, offering a blueprint for future restoration efforts. Thank you, Darcy, for joining us, and a special thank you to NSLA for their continued stewardship across the North Shore.
Watch Darcy’s “The Ever-Evolving Management of Mugwort in the Humes Preserve Meadow” presentation here.
