Should large invasive trees be removed and replaced with native species?
Question:
I’ve been slowly working over the last few years to remove a rather large amount of invasive plant species dotting my property and replacing them with alternative species. I’ve got several different kinds, but the three most pervasive are Asian Bush Honeysuckle, Norway Maples, and Multiflora Rose. They’ve taken over everything, and have all been here since I bought the place. If the trees were small I just pulled them up, but my question is for the larger trees. I’m trying to do the right thing, but I’m not sure if it’s better to remove a larger, established but invasive tree and replace it with a smaller, native species, or allow the larger tree to go on. I’m happy to do either one, but want to cause the least amount of environmental impact. I’m in a suburban area, and large trees are in the minority. I’d be happy to spend some time and energy into growing a young tree into a larger one if it makes the most sense, impact-wise.
Answer:
Abi Griffith, Horticulture Community Education Assistant
Kudos to you for putting in so much work on your property! It’s a big effort!
As far as addressing your more established invasive Norway Maples, you may want to reference this fact sheet – Norway Maple, which includes control methods. One approach could be to put your efforts into first implementing less dramatic control methods, including keeping an eye out for saplings and pulling them up, which you sound like you are on top of, as well as raking up any seed and removing it to control the seed spread as much as you can each summer. Then you can make a plan to start planting new native trees and/or shrubs on a regular basis, appropriate to your site and budget, to begin establishing some new landscape before removing the invasive trees. This page – Plants for a Maine Landscape contains a lot of resources to help you consider what to plant depending on your site. Planting a variety of plants may help you with space constraints.
This approach may depend on how big your trees are currently. When removing a large tree like Norway Maple, the two biggest concerns are related to soil erosion and the loss of habitat. If those two areas aren’t too big of an issue on your property, perhaps removing it in the near future would be the way to go. Another consideration is that Norway Maples have shallow roots so they’re more likely to come down during a bad storm compared to many of their native counterparts so another question is how close is the tree to your house? That could be another reason to take it down sooner than later.
It sounds like you have appropriately approached this battle against invasives with a long term view, and a more gradual approach could be less disruptive overall. Of course, if you want to look into tree removal, here is the link to the licensed Maine Arborist List and what to think about when hiring. This will help give you more information needed to make the right plan for you.