Invasive Species
Invasive exotic species, by definition, are those species that have been introduced through intentional or accidental methods into a place where they were not originally growing. One of the most notable characteristics of invasive exotics is their ability to grow and spread aggressively. This characteristic permits these species to form dense populations that will exclude many species of flora and fauna native to Pennsylvania. In many cases, they become so aggressive and widespread that they are nearly impossible, if not very expensive, to control.
Invasive species often target natural areas. In a battle for habitat, they displace native plants and animals and alter ecosystem processes. Ecosystem alteration can come in the form of changes in the availability or quantity of water or nutrients, the rate of soil erosion. the frequency of wildfires, (which is a natural process that some ecosystems depend upon), light availability to plants in the ground layer and shrub layer, and, in some cases, the incidence of cross-breeding with native species, which alters the natives' genetic makeup. Endangered or threatened native species are especially at risk, since their populations are often small and more vulnerable to competition by invasive exotics.
Battling the Problem
We can work to control the spread of invasive species through scientific strategies. An important aspect of management, however, is educating others about the problem and discouraging intentional introductions through methods such as nursery sales and trade. Other strategies include:
· Continual Monitoring: Early detection is our greatest asset because the smaller a population of an invasive exotic is, the more controllable it is. Detecting an exotic invasive plant before it goes to seed is ideal because it can be eradicated before it has a chance to spread.
· Manual or Mechanical Removal: Removal, done through pulling, digging, cutting or trapping is effective if populations are small or if sufficient manpower is available. For annual and biennial plant species, cutting is sometimes preferable to pulling the plant, because disturbing the soil can itself encourage the establishment of more exotic species.
· Burning: In cases where an invasive exotic plant is widespread, burning is an effective method of management if performed in a controlled manner by trained professionals. Burning should only be done in situations where it is controllable and native plant and animal communities are spared.
· Chemical Application: In cases where an invasive exotic population is too large to be controlled by the above methods, resource managers will sometimes resort to the use of chemicals. In this situation, the careful use of effective chemicals that are the least persistent and most environmentally friendly may be justified. Often, herbicides can be manually applied to individual members of the invasive plants, minimizing exposure of non-targeted species to the chemicals.
· Biological Control Agents: These are organisms that feed on invasive exotic populations to keep them at low population levels. Such organisms are released into the environment in an effort to reduce the invasive populations. However, a concern of this methodology is that the practice requires introducing yet another exotic species into the environment with unknown ramifications.
What Can You Do?
Your greatest asset in contributing to the battle against invasive species is knowledge. Get educated on what invasive species look like. Avoid the introduction of invasives in your landscaping at home. Learn about erosion control on your property and how to pick wildlife food that won't allow uneaten seeds to sprout as an invasive species.
