by Sherry Lyons
Many of us have heard a lot about invasive plants, and others are just starting to learn about them. There are varying degrees of concern about them, but in general, they are labeled “invasive” because they are not native to the area and they don’t have any natural predators or deterrents to their survival. Often they crowd out, damage or kill native plants, while not providing a habitat where our native wildlife can thrive.
Beth talked about and described Oriental or Asiatic bittersweet (Celastrus orbiculatus) at our September meeting. I mentioned that I am a member of the Bittersweet Brigade, a team of people that volunteer for Coastal Rivers to remove bittersweet and other invasives from the preserves they manage and protect.
You may be aware of its beautiful berries and lovely twining structure, just inviting you to use it to make wreaths decorating your house, but don’t do it. Those berries are seeds that are spread by people and birds that become vines that thicken and grow to twine around trees, strangle and kill them.
Another invasive you may have heard about is Japanese knotweed (Fallopia japonic). It is listed as one of the world’s ten most invasive species. It is almost impossible to eradicate. It can grow over 4 inches in a day, through pavement, concrete and masonry, damaging the buildings’ structural integrity. The best most people can do is to cut it down before it flowers, so that it does not spread further. Other options are having a professional applying an herbicide or bulldozing it to get the roots. They must be disposed of properly so that they do not take hold somewhere else. On the positive side, the young shoots and leaves can be eaten, tasting like a cross between asparagus and rhubarb, but this is not enough of a reason to cultivate them, knowing all the damage they can do .
“Japanese knotweed can severely degrade the quality of wetland and riparian habitats where it becomes established. Dense thickets can reduce sunlight penetration by more than 90% and its thick mats of dead and decaying vegetation in fall/spring prevent other plant species from growing by shading them out.
As a result of the reduced native plant biodiversity and lowered invertebrate densities, established knotweed stands do not support the same levels of native amphibian, reptile, bird and mammal populations. For example, it has been shown that native green frog (Rana clamitans) presence is dramatically reduced in knotweed stands in riparian/wetland areas. Although further study is needed, it is believed that Japanese knotweed may have allelopathic properties. The roots contain unique compounds, which may alter soil chemistry or prohibit the growth of nearby native species (Japanese Knotweed BMP).” https://www.invasivespeciescentre.ca/invasive-species/meet-the-species/invasive-plants/japanese-knotweed/
Another invasive that is quite beautiful is purple loosestrife (Lythrum salicaria). It grows prolifically in the marshes and wetlands all over the state and beyond, displacing the cattails that many marsh birds like red-winged blackbirds depend on for nesting and camouflage.
“Purple loosestrife negatively affects both wildlife and agriculture. It displaces and replaces native flora and fauna, eliminating food, nesting and shelter for wildlife. Purple loosestrife forms a single-species stand that no bird, mammal, or fish depends upon, and germinates faster than many native wetland species.” https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/2020-01/bb-45.pdf
To avoid an overload of information, I will continue to enlighten you about other invasives over the course of the year. Keep on gardening!
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