Invasive Species 1: Japanese Knotweed

One of the major problems facing our parks is the presence of invasive species. Now, and as Riparian restoration efforts move forward, infestations of these harmful plants threaten our park ecosystems. Invasive species are defined by the Pennsylvania Department of Conservation and Natural Resources as: “a name for a species that has become a weed pest, a plant which grows aggressively, spreads, and displaces other plants. Invasive plants tend to appear on disturbed ground, and the most aggressive can actually invade existing ecosystems. Invasive plants are generally undesirable because they are difficult to control, can escape from cultivation, and can dominate whole areas.”

There are many plants that meet the criteria of invasive species. In our park system, there are some particular offenders that I am going to spotlight on this blog. Before I get to that though, I think it is important to define the characteristics of invasive plants in general. From the DCNR: “invasives are not native to North America; spread, reproducing by roots or shoots; mature quickly; if spread by seed, produce numerous seeds that disperse and sprout easily; be generalists that can grow in many different conditions; and be exploiters and colonizers of disturbed ground. “

Let me now introduce you to a chief offender: Japanese Knotweed. This guy is a real pain in the neck and is a very damaging plant. I recommend reading the very detailed and through fact sheet located here that the DCNR has set up if you need to be acquainted with this particular invasive.

Japanese Knotweed has established its presence in many of our parks but none as much as Trout Creek Parkway.







As you can see from those pictures, Japanese Knotweed has taken the park over. Long sections of the creek bank are entirely made up of this plant and it is here you can see the full damaging effects of this invasive species.

Removal of Knotweed is tough. It is an incredibly resilient plant that requires the entire root system of each individual plant to die or be removed for the plant to truly be knocked out. There are plans in the works to begin to deal with the infestation at TCP and I hope they are successful. This plant is a monster.