If you are a gardener, have an interest in the natural environment or are just a curious person, you have likely heard the terms, native species, non-native species and invasive species.
Native plants and animals are those that occur naturally in a location and have for many hundreds or thousands of years. The native plants and animals of a region exist in morphological and chemical relationships that have co-evolved and form life supporting networks or ecosystems.
Non-natives, such as the European honeybee here in America, are often introduced species, brought from other regions, countries, or continents because of some useful or pleasing attribute. Most non-natives are not invasive and like the honeybee, co-exist with the natives. Non-native species may also be introduced accidentally and sometimes, as with the spotted lantern fly, with a disastrous outcome. Invasives, like the spotted lantern fly, are those plants or animals that are non-native, spread quickly and out-compete other species, interfering with the natural balance within an ecosystem.
Healthy ecosystems support a variety of organisms. This array of living things, or biodiversity, includes plants, birds, insects, reptiles, fungi, bacteria, etc. The greater the variety of living things, the more likely the system can withstand a change. When invasive plants move into an area, they replace other plants, creating monocultures with one dominant plant. In a monoculture, bio-diversity goes down. Native plants and all their associated organisms disappear, and the resilience of the ecosystem declines. This decline may be referred to as habitat loss.
Norway maple, Japanese barberry, and burning bush are among popular introduced landscape plants that have become invasive. These plants, and many others, escape our gardens, reproduce quickly, shade out or crowd out native plants and threaten the biodiversity of the places we typically associate with wildlife.
Natural areas, such as state and county parks, are experiencing inundations of invasive species. Today, it is common to see entire woodland edges covered with non-native vines such as Oriental bittersweet, honeysuckle and porcelain berry.
Another better-known escapee, English ivy, is a vine widely considered to be a maintenance-free ground cover. English ivy can make its way into trees by climbing. The vine then competes for the air, nutrients and light that trees need to be healthy. This competition causes irregular limb growth and the weight of the vine stresses the tree. As the vine reaches higher branches, it begins to fruit. Birds like robins and starlings eat the fruit and disperse the seeds. In this way, the ivy moves into woodlands, where it will eventually overtake the trees there. On the ground, it can be contained but should be removed from trees to prevent damage, premature decline of the tree and the spread of the vine to other places. (Note: If you are going to remove ivy research safe techniques or watch online videos first to avoid damaging the tree.)
Efforts to control invasives have been on-going for years, and costs to control them in agriculture, roadways and parks are high. The state of Delaware has an Invasive Species Council and a Native Species Commission. These entities are working to educate the public about the invasives and how we can make a difference. Newark’s Sustainability Plan also addresses the problem, urging control of invasives and planting natives in city parks.
One way to help reduce the problem is to to become familiar with the common invasive plants and remove them from your property. Many invasive plants, such as periwinkle, daylilies and English ivy, are still available for sale at garden centers. When you shop, ask for native alternatives to non-native plants. There are many and native plants in our landscapes support our wildlife. An excellent resource for understanding the problem, techniques for control and for information on alternative plants is ”Plant Invaders of Mid-Atlantic Natural Areas” published by The National Park Service and U.S. Fish and Wildlife.
The Conservation Advisory Commission was created in 1977 to advise the city of Newark in the development, management and protection of its natural resources, with appropriate consideration of Newark’s human and economic resources. It meets the second Tuesday of each month at 7 p.m. in council chambers. The public is invited to attend and provide input. Commission members provide this monthly column to inform area residents on conservation issues.