The Buck(thorn) Stops Here
/By Victoria Erhart, 2021
Michael Sinclair (L) and Nile Merton (R) of Bay Area Environmental Consulting, with recently treated buckthorn
Last fall, I went with several MIWP board members to tour two sites recently treated for buckthorn by Bay Area Environmental Consulting, Nile Merton and Michael Sinclair. The first site, requiring some fancy foot work and rubber boots, was a dense black ash swamp previously infested with equally dense, pole-sized buckthorn. The buckthorn were standing but obviously dead, the ash were healthy. At the second site, across Middle Road from the first, there was a gloriously grassy open field ringed with quite beautiful mature buckthorn trees, also standing and dead in spite of the fact that they had been treated only a couple of weeks before. I was struck by how much our approach to buckthorn removal has changed since those early years when we believed we could get rid of it completely. It is always a hard, dirty business, but we now have a systematic seven-year plan, we are effective and efficient, we no longer do all that very labor-intensive cutting and hauling, and our focus is more on keeping the bad stuff from spreading than on making it go away completely.
What’s so bad about buckthorn? Buckthorn, and barberry which we also treat, are non-native escapes from horticulture, from gardens. What’s wrong with them is that they do too well, grow too thickly, and spread too widely. They outcompete most native plants and thrive almost everywhere including moderate shade. Buckthorn may secrete a substance toxic to other plants, barberry encourages deer ticks. Both destroy the normal diversity of the plant community which then leads to a loss of insect diversity, an ecological desert. If we do nothing, they will cover most of the Island.
What is this “seven-year-plan” you mentioned? Year one, 2018, was a data-gathering year. Nile mapped all of the buckthorn on the Island, including density and size of stands. Since most of the buckthorn arrived in nursery pots for gardens, it is not surprising that you find most of it in an area close to town, but it has been spreading outward, mostly following roads.
Based on that mapping, Nile defined six treatment zones, and for the last two years we have been treating a zone a year, starting with the outermost zones to keep buckthorn from moving into areas where there is none. 2021 will be the third year of treatment; this year we will be both treating the third zone and monitoring/re-treating as necessary in zone 1. This combination of treating the new and reevaluation/re-treatment of the old will go on for at least the next four years. At the end, most areas will have been treated at least once and we’ll get to pause, reflect, and see what comes next.
Can the MIWP do this by itself? Absolutely not. To our embarrassment, some of the worst buckthorn infestations are on MIWP land and we can treat those without permission, but there is still a lot of buckthorn on private land. Every year Bay Area Environmental Consulting sends letters to landowners who live within this year’s treatment zone and who have known buckthorn or barberry, offering to treat at no cost. We would love to treat your buckthorn for free, but know that the one thing we don’t do is cut down and haul away the dead wood, although we can refer you to someone who can.
How do you get rid of buckthorn? It’s easier to talk about what doesn’t get rid of buckthorn. If you cut it, it resprouts and multiplies. Digging it out is not possible on any large-scale basis, and disturbing the soil brings viable buckthorn seeds to the surface and gets you more baby buckthorn. Fire might theoretically knock it back in some environments, but not on Madeline. One summer we tried goats, which eat everything, but goats are not selective and the buckthorn just grows back. There are ongoing studies of planting native plants to compete with buckthorn, an idea that I like, but I haven’t seen any successes yet. Which leaves herbicides.
Herbicides? In the current state of invasive treatment, really the only way to get rid of buckthorn on a landscape scale is with herbicides. BAEC uses triclopyr and, more importantly, uses it in a very targeted way. There is never any generalized broadcast of the herbicide, and there’s no overspray. Surrounding plants don’t seem to be affected, something we were careful to notice in that black ash swamp. I don’t like herbicides and I try not to use them in my garden, but the goal is to safeguard the health of the forest. In the big picture, herbicides, used carefully and with training, present a lot less risk to the environment than letting buckthorn, barberry, and non-native honeysuckle all run wild.
Might climate change have an effect on buckthorn? Yes, but not in a good way. From a U of MN study by Peter Reich: Buckthorn has slowly increased in abundance in northern Minnesota in recent decades, perhaps slowed by cool summers, but it thrived in warmer experimental conditions. This is bad news, as it suggests that buckthorn and other invasive species might take advantage of climate change and more aggressively move up north.
What do you see happening to this program in the long term? Good question. My dearest hope is that sometime soon someone develops some kind of biological control, as there is for spotted knapweed, and we can stop all this monitoring and treating and sit back and enjoy our forests in their full health and diversity. I don’t see that happening soon. Realistically, I am hoping that the treatments we do are effective enough that over time we can ease off on what we are doing. Maybe we will be able to monitor every other year, and cover larger pieces of land because there is less to treat. Maybe we can do even less than that. I think there is some truth to the idea that treating invasives is forever, but I can imagine a time when buckthorn is a minor nuisance rather than a major threat.
Can I do something to help? Learn to recognize buckthorn and barberry when you see them (in small numbers you can deal with them in a non-chemical way). Say yes if we ask to treat the buckthorn on your land. Be very thoughtful about making unnecessary openings in the forest; while buckthorn tolerates more shade than many plants, it can’t establish itself under a dense forest canopy. Join the MIWP, come walk our lands and see for yourself. Thank you!
