When I talk about illegal plants on Long Island, I’m NOT talking about a certain one used for “medicinal” purposes. What I am talking about are invasive plants. Two years ago, it actually became illegal to sell, transport, distribute, and propagate dozens of invasive plants in both Nassau and Suffolk Counties. Invasive plants are not just harmless little weeds and dandelions - invasive plants are the thugs of the plant world. They can cause considerable damage to natural habitats by invading ecosystems which they are not native to, and displacing the native flora. The population of native plants is then reduced or even wiped out in some cases. This in turn affects wildlife and other species which may be dependent upon the local flora for food or habitat. The introduction and spread of invasive species is the second leading cause of global biodiversity loss. (Habitat loss is the number one leading cause.) About 42% of species listed on the U.S. Threatened or Endangered Species Lists are at risk primarily due to competition or predation from invasive species.*
Photo: The invasive vine, Sweetautumn Clematis (Clematis terniflora), engulfing vegetation along the Peconic River in Riverhead
You may be asking, so how do these tough non-native plants overtake our “wimpy” native plants? The answer can be explained by evolution. Because a non-native plant did not evolve with the local species, it may have few or no herbivores or pests that like to eat it in its new location. It also may have developed superior ways to acquire essential resources such as water or sunlight compared to the local species, which makes it a better competitor. Like real thugs, these invasive plants also bring bigger and badder gats to the gunfight. Certain characteristics allow a plant to adapt quickly to a new environment, thrive, and spread. Most invasive plants possess one or more of these characteristics which include, abundant reproduction; rapid growth rate; short generation time; ability to occupy many different habitats; ability to adapt to changing environments; effective seed dispersal; long-lived seeds; and being poisonous or allergenic to other organisms.
Photo: The invasive shrub, Autumn-Olive (Elaeagnus umbellata), colonizing an old field in Calverton
So what might look like some nice greenery, might actually be the battlegrounds of ecological warfare, where rampant, Oriental Bittersweet vines (Celastrus orbiculatus) are engulfing full-grown trees, Phragmites reeds (Phragmites australis ssp. australis) are choking out waterways, and Mugwort (Artemesia vulgaris) is invading our gardens. The cost of controlling invasive plants is mind-boggling! In 2005, the annual cost to the US economy for invasive herbaceous weeds (not including trees and shrubs) was estimated to be $27 billion in crop systems, $6 billion in pastures and rangeland, $1 billion in golf courses, and $500 million in residential yards and gardens!*
Many people are working hard to control invasive plants, including park and wildlife refuge managers, botanists, environmental engineers, landscapers, and now even Long Island legislators. But even the world’s top biologists and ecologists cannot predict what the outcome will be of this ecological war – will most species of native plants perish in the wake of invasive plants? Will native and invasive plants establish an equilibrium and co-exist? Will invasive plants die-out in a couple decades or centuries as the native flora and fauna evolve with them?
Although the answers to these questions remain unknown, “thinking globally and acting locally” rings true in this situation. Being concerned about global biodiversity can spur us to action in our own backyards and gardens. You can start by learning how to correctly identify invasive plants and remove them from your yard. Definitely make sure to not buy illegal invasive plants that are now banned on Long Island. You may want to consider growing or planting species native to Long Island or the Northeast. Native plants are a wonderful way to preserve local biodiversity and attract birds and wildlife to your backyard. However, be sure to remember that there are also many non-native, NON-invasive ornamental plants that also make great selections, especially if you are planting in a tough location.
For the list of illegal plants on Long Island, visit http://ccesuffolk.org/nursery-and-landscape-current-projects/. This page will also give you suggestions for alternatives to long-standing ornamental plants that have been found to be invasive, like Norway Maple (Acer platanoides) and Japanese Barberry (Berberis thunbergii). By each of us doing our part, maybe we’ll eventually be able to win the weeds war!
Photo: The invasive ornamental shrub, Japanese Barberry (Berberis thunbergii), can produce up to 9,900 seeds per plant, depending on cultivar
*Source: Pimentel, D., R. Zuniga, and D. Morrison. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52: 273 – 288.
