Overview
- In Washtenaw County, invasive plants are not just a backyard nuisance—they’re one of the biggest drivers of long-term habitat loss in woodlots, wetlands, and the Huron River watershed, and Matthaei Botanical Gardens & Nichols Arboretum have become a local model for tackling the problem at scale through coordinated stewardship and public engagement. (Eco Workdays).
- Winter creates one of the most productive windows for this work in southeast Michigan because leaf-off conditions make woody invasives easier to spot, access, and remove, especially the shrub layer that chokes out native regeneration. MBGNA’s stewardship events explicitly include winter-style tasks like “cutting invasive shrubs and trees,” reflecting the reality that dormant-season fieldwork is often when crews can make the largest structural improvements to invaded habitat before spring growth starts (Student Stewardship Day).
- This winter work is supported by a practical equipment toolkit that matches what restoration crews use across the region: MBGNA stewardship operations list field tools and power equipment including chainsaws, brush cutters, loppers, handsaws, and a wood chipper, plus vehicles and machines like tractors, mowers, and utility vehicles—the kinds of tools needed to remove dense invasive brush efficiently, safely, and at the scale required for real ecological impact (Natural Areas Stewardship Technician posting).
- Matthaei’s restoration work also shows why invasive control is often framed as a multi-year, data-driven process rather than a one-time clearing effort. In sensitive habitats like prairie fen and wet meadow systems, MBGNA reports that current restoration priorities include removing invasive shrubs—particularly common buckthorn and glossy buckthorn—because they outcompete native plants and disrupt the ecological conditions needed for recovery, with planned follow-up that includes reseeding native plants and prescribed ecological burns (Prairie Fen Restoration at Matthaei).
- Matthaei and Nichols connect hands-on work to measurable tracking—an approach especially relevant in Washtenaw County where restoration success depends on repeated follow-up. MBGNA maintains public-facing natural areas GIS resources and a dedicated public map layer that shows invasive species locations across its properties, including Matthaei, Nichols, and Horner Woods, demonstrating how crews can prioritize dense stands, monitor progress, and plan return visits as invasives re-sprout or re-seed over time (Natural Area Data Resources; Invasive Species Public View map layer).
Transcription
David Fair: This is 89.1 WEMU, and on today's Issues of the Environment, we're going to deal with invasion. I'm David Fair, and what we're talking about is invasive plant species. These non-native plants are not just a nuisance but a real ecological problem. There are good works being done to deal with this exact problem, and you need look no further than Matthaei Botanical Gardens and Nichols Arboretum. Those local institutions have become a model in stewarding management or mediation of the non-native plant problems. Joining us today is Steven Parrish. Steven serves as Natural Areas Specialist at the gardens and arboretum. And thank you so much for the time! I appreciate it!
Steven Parrish: Glad to be here!
David Fair: I've been doing this Issues of the Environment segment for over 30 years now, and all that time, invasive plants repeatedly come up as a focal point. Here in 2026, how pervasive is the problem in Washtenaw County on the Huron River Watershed?
Steven Parrish: Well, we have woody plants that have been intentionally brought here and accidentally. And European buckthorn is probably going to be the most important one. It really shades out our natural areas. And here, we have, at the Botanical Gardens, probably 60-year-old buckthorns. So, they've been here decades casting shade and making it difficult for our native plants and the animals that thrive on those plants successfully co-habitate. And we have new plants every year it seems--new invasive plants with globalization. We have a lot of Oriental bittersweet vine. It's a woody vine. I see it almost as kind of cudzoo of the north. So, yeah, we are continually trying to find ways to manage these plants through a variety of different means.
David Fair: Not all non-native plant species are illegal to bring into the U.S., but there is a pretty strict regulatory process for getting permits to do so. You mentioned that some have been brought here intentionally, and some have kind of snuck their way in. How do so many species make it into our natural areas?
Steven Parrish: There have been ones here for many years, and it kind of took a while before it kind of became a critical mass. And so, buckthorn has been here for probably over 100 years, but it's only been in the last 40 or 50 that they've been a real problem. So, I think they just kind of bided their time, and they're actually dispersed by birds, largely. Other plants are wind pollinated, or wind dispersed rather. And so, those are actually really problematic as well. We have one called Black Swallowwort. It's a member of the milkweed family, and if you know anything about milkweed, the fluffy seeds that fly up in the air--
David Fair: It's when it snows in the spring and summer. Right.
Steven Parrish: Exactly, yeah. And so, you can have a population in one area, and then it just leaps over. And then, it's just wherever the seed is took and really, really hard to manage. But with the regulations, not many are coming in here intentionally anymore, but it's just they hitch a ride on pallet material, the seeds, or if we're even talking about invasive animals, like the emerald ash borer, that came in on palate material from Asia. And so, with regulations, they're doing a good job, but it's what is already here and what it's accidentally brought in, which is what the real problem is.
David Fair: We'll talk about how we're dealing with, managing, and trying to remediate some of these issues, but perhaps you can explain what happens to the ecology of our land, to our watershed, and to our animal life when some of these species begin to crowd out the native landscapes.
Steven Parrish: You know, these plants evolved largely in Europe or Eurasia, and there are checks and balances wherever any plant is growing to kind of keep them in check--fungus, disease, insects, when you bring something from another continent, then, likely, there are very few, if any, of these insects, pathogens, that kind of keeps the numbers down. You know, every plant is vying for sunlight. And when you have a plant that is fast growing, it's interesting if you look at the leaf of, say, a cherry tree versus the leaf of a buckthorn, you will see no insect damage on the buckthorn, but the cherry leaf will have bite marks. And so that leaf is providing a--
David Fair: Sustenance and food. Yeah.
Steven Parrish: Yeah, for our local insects. And what eats the insects--the birds and so on. So, these non-native plants are sometimes deemed kind of sterile. They provide little to no ecological services. And you mentioned watershed. They actually increase erosion because they crowd out the herbaceous plants. And it's those small, fine root hairs on the roots that help lock that soil in place. So, when you have this dense shade, then you have these big water events. Then, you actually increase the erosion because the lack of these fine root hairs that are found in our herbaceous layer.
David Fair: This is 89.1 WEMU, and our Issues of the Environment conversation continues with Matthaei Botanical Gardens and Nichols Arboretum Natural Area Specialist Steven Parrish. I kind of assumed that most of the work to address the non-native plant problem each year would blossom in the spring with the greening of the trees, but it turns out I may have assumed wrong. Why is winter, this time of year, these conditions, vital in managing the invasive plant life in our local ecosystem?
Steven Parrish: Yeah. Woody plants, trees and shrubs and some vines are best managed in the wintertime for a number of reasons. We have a number wetlands on the property, and if you were to go in there in the summertime, it's a wetland. It's really muddy and mucky. And in this winter in particular, it's really cold. It's covered with snow. And so, you can get out into these sensitive wet areas with heavy equipment and manage some of this stuff without causing as much disturbance to the soil. And all the animals are, especially the snakes or rare snakes, they're hibernating right now. And so, we're not endangering a number of animals as well. So, it's easier to see. There's no leaves on the tree. You can see the shape of the land. And you can really do some heavy-duty clearing of these non-native shrubs and trees quite easily, and the results are very satisfying and long-lasting.
David Fair: I mentioned at the outset that the work your team is doing at the Botanical Gardens and Arboretum are considered a model in the field. As that work is being completed in the winter and on forward through the year, what work is done to restore native plants and vegetation as future protections?
Steven Parrish: Yeah. After we do clearing of these invasive shrubs, then there are a number of different tools we can use--techniques that we can use--to help fill those voids. One thing we did last year, and we plan to do this year again, is called live staking, which is where, at the very end of the winter or very early spring before bud burst, you can cut sections of stems of woody plants--dogwood, willow, nine bark, elderberry--about 18 inches long, about a rule of thumb size, and you basically jam them in the ground. It needs to be in a pretty wet area. You want to have about two-thirds of the plant stem into the ground.
David Fair: Then it takes on a life of its own, doesn't it?
Steven Parrish: Basically, yeah. You can reinforce stream banks and wetland areas. And so, it's pretty low maintenance too. You just go out and cut these stems off, you soak them in some water with some willow branches, and the next day, you pop them in the ground with a rubber mallet. We had really good success too, probably 50%, but we put four or five hundred life stakes in last year. And that's 250 plants. And so, that's one way. You can also put native seed down in some of these areas because now that there's an excess of light, sunlight, you're gonna trigger some of the native herbaceous plants. Sometimes, we'll even just see what pops up because, sometimes, that seed is lying dormant, and all it needs is a little bit of sunlight to open it up. And then, you can have nice rare plants even coming back where once we didn't have them or know that they existed there.
David Fair: I really appreciate you explaining all that you have and taking time to take us through the process of preparing through the winter and working towards the spring and the greening of the state of Michigan and Washtenaw County. Thank you for the conversation, Steven!
Steven Parrish: Happy to be here! Thank you, David!
David Fair: That is Steven Parrish. He is Natural Areas Specialist at Matthaei Botanical Gardens and Nichols Arboretum in Ann Arbor and has been our guest on Issues of the Environment. If you need more information, stop by our website at WEMU.org. Issues Of The Environment is produced in partnership with the Office of the Washtenaw County Water Resources Commissioner. You hear it every Wednesday. I'm David Fair, and this is your community NPR station, 89.1 WEMU-FM Ypsilanti.
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