Invasive plant species are non-native species and have no natural controls to keep their populations in check. Therefore, they can spread rapidly and outcompete the native vegetation, which has a detrimental effect on natural habitat and food sources for wildlife. They do not coexist with other plants but overrun them, thereby lessening diversity in the woodland.
When vines such as bittersweet run to the top of a tree, they cover the tree top in their own attempt to get sunlight. The heavy vines make the tree vulnerable to snapping off in a windstorm. You will see many trees in the park which have been broken in this manner. If the tree does not break off, the vines will eventually kill the tree anyway by absorbing all the sunlight and not allowing the tree leaves to photosynthesize and feed the tree.
When a tree breaks or falls in the woods, the wind stress on the remaining trees increases, and they too become more vulnerable to damage in a windstorm.
Ground-based plants such as Japanese Knotweed grow so rapidly and so thickly that the area beneath them becomes inhospitable to other life. Young trees cannot get established, and fruiting shrubs which would otherwise feed birds and mammals also cannot grow. Norway maples develop a thick shallow root system that prevents anything else from growing beneath them. Their prolific seeding ability means that new trees quickly establish any open ground, preventing the growth of more desirable species. Tree of Heaven is another invader with a habit of quickly colonizing open ground.
Last summer the MLNC began an aggressive campaign to begin to manage this issue and to restore the health of the parks. We meet at least one Saturday each month (usually the third Saturday) to cut and clear invasive vines and other plants. The more help we have, the quicker we can accomplish our goals, so please consider joining us for a hour or two. While we will probably never completely eliminate the invasives threat, we hope that in a few years our efforts will be more in monitoring and less in removal.
What else can you do? Do not empty garden waste into parks or wooded areas. Cuttings from plants such as English ivy, vinca and pachysandra can quickly take hold and overrun a park. Piles of cut grass or leaves smother the ground and do not allow new native vegetation to sprout.
Also, if you find any of these invasives growing on your property, remove them if possible and dispose of them properly. Educate yourself to recognize these invaders, and spread the word, to help ensure that our community’s bio-diversity remains healthy.