Woody Invasives Update
/By Dan Engstrom, MIWP Forest Management Committee
The Madeline Island Wilderness Preserve has been battling the spread of woody invasive plants — buckthorn, barberry, and Eurasian honeysuckle — on our Island for more than 15 years. That effort, initially carried out by volunteers and seasonal interns, took a quantum leap in 2018 when we hired Nile Merton and his company, Chequamegon Environmental LLC (formerly Bay Area Environmental Consulting) to develop a systematic, island-wide plan to control the invasion and the threat it poses to the health of our Island forests. Now in its 6th year, the program has made remarkable strides.
The basic idea behind this long-term effort is to slow/halt the spread of these aggressive invaders from their population centers in and around La Pointe where they were first planted as ornamentals and hedgerows more than a century ago. The invasion has been slow but inexorable and now extends beyond the airport, out along Middle Road, and south to Grant’s Point. The control work has proceeded by geographic zones, working first from the outer edge of the invasive front, inward toward the center (in town) where it is now focused for 2024 (see figure).
The invasives are carefully targeted with herbicide application to mature stems of buckthorn and honeysuckle and foliar spray of smaller seedlings and barberry. Resurvey and a follow-up treatment of each zone two years later has shown better than 90% effectiveness with little invasive regrowth and little impact on non-target native plants. Alternative treatment approaches such as pulling or cutting are not feasible nor effective on this Island-wide scale.
In addition to MIWP and Town lands, permission is sought to treat private properties. Each spring Nile sends out an information packet and a permission form to land-owners in the scheduled treatment zone. Response to these requests over the years has been strong, and we very much encourage landowners who receive one this year to grant approval to survey and treat their properties. It is only through such collective cooperation that we can effectively control the spread of these noxious plants on our island.
The current control program will continue for four more years beyond 2024 with resurveys and follow-up treatment of previously treated zones. Thereafter, and on a much reduced schedule, MIWP will continue to monitor and spot control regrowth and missed populations. Based on our effectiveness thus far, we expect this to be mostly low-level maintenance and vigilance. The success of MIWP’s invasive control program is impressive and owes much to the skill and hard work of Nile Merton and crew, but also to geography — an island with a great deal of intact closed-canopy forest (which resists invasion) and invasive numbers mostly localized near town. It is also a tribute to you and the many other supporters of MIWP. When completed in 2028, our invasive control program will have cost in excess of $150,000 — a very large sum for our small, all-volunteer organization and made possible only because of your generosity.
