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Invasive species removal to start in Rotary Park
Published: 12/13/2021
Large areas of buckthorn and other woody invasive species will be removed from two sections of Rotary Park in late December. The removals will take place in the area facing Nine Mile Road and in an area south of that, along the pathway between the parking lot and Chase Farms. 

This work is a continuation and expansion of the efforts the City started in 2016 to improve the environmental health of our parks.

Common buckthorn and glossy buckthorn are the most prevalent woody invasive species found in the park. They are small trees native to Eurasia and were brought to the United States long ago as a privacy-providing plant, due to their dense cover and long period when they have leaves (longer than most native trees and shrubs). They are spread by birds who eat the black berries and drop the seeds wherever they perch. Buckthorn poses several problems for native habitats:
  • Its dense cover shades out native plants on the ground (wildflowers, grasses, sedges, ferns).
  • Its dense cover also shades out native trees and shrubs and prevents regeneration of the natural forest since the young sprouts don’t get enough sun to grow.
  • The berries it produces do not produce quality calories and nutrients for the birds that eat them, unlike the native trees and shrubs.
  • The seeds have high fertility and germination rates, so they can out-compete natural seeds for available sun, water, and nutrients.
  • The tree’s leaves increase the amount of nitrogen in the soil and change the soil chemistry as they decompose, favoring the buckthorn over the native plants and reducing leaf litter from native species which can be beneficial to native plants and animals.
  • The fruits and roots are also allelopathic, which means they put out chemicals that can make some plants unable to grow in the area with the chemicals.
  • As the ground beneath a dense stand of buckthorn is typically bare, the plants that would typically absorb and slow down water in flood events in floodplains such as Rotary Park are not there, leading to more soil scraping and downstream deposition than would normally occur.
  • In addition, they detract from the human experience by blocking views into the woods and reducing the number of birds and other animals that may be viewed as we walk along the paths. 
For all of these reasons, the City has been removing buckthorn and other woody species such as honeysuckle and autumn olive from Rotary Park and other City parks. Money from the Tree Fund is used for these efforts, and the City has hired a contractor to remove buckthorn from the area highlighted in red on the map above.

This year, the City was also awarded a $15,000 grant from Oakland County Parks and Recreation for community invasive species projects to do some extra removals. The area shown in blue on the map will be done by a contractor hired by Oakland County Parks. That contractor will be using a combination of high-intensity mowing equipment and power saws to remove as much buckthorn as possible in that area. The City contractor will only be using power saws. 

The appearance of both areas post-clearing will be quite different from how they look now, which is a good thing. More sun will get to the ground layer, encouraging more herbaceous plants that provide food for birds and other animals. We have seen an increase in butterflies in the areas we’ve cleared along the Rotary Park path in previous years.

It will take a year or two for this growth to really show up, for the wood chips to decompose, and for the soil to recover from the impacts of long-term buckthorn occupation. Once those effects are diminished, native seeds from the seedbank often grow and start to restore the area to a more natural state.  The City will also add native floodplain plantings to enhance the habitat.

Unfortunately, follow-up treatments of buckthorn resprouts are always required, which involve more cutting and some herbicide application to cut stumps and resprouts, so this clearing is only a first step toward a truly healthy habitat. Without it no regeneration would occur and it is likely that the condition of the park’s habitats would continue to deteriorate. While the area may look very different once the clearing is done, know that it is not part of any construction project, but rather a reconstruction project, of a healthy, more natural Rotary Park.

If you have any questions about the process, please contact Rick Meader, Landscape Architect, at rmeader@cityofnovi.org or (248) 735-5621.