out-compete native undergrowth and prevent forest regeneration. Photo credit: NYS DEC.
An invasive species does not naturally occur in a specific area: it is non-native to the ecosystem. The introduction of a non-native species can cause harm to the environment, to the economy, or to human health.
Since invasive species are in a new environment, free from natural predators, parasites, or competitors, they often develop large population sizes very rapidly. These large populations can out-compete, displace or kill native species. Non-native species can reduce wildlife food and habitat. Some also have the potential to disrupt vital ecosystem functions, such as water flow, nutrient cycling, or soil decomposition. Other invasive species cause massive amounts of economic damage to the agricultural business by destroying crops and contaminating produce. Some invasive species can cause direct harm to humans or domestic animals.
How do they arrive?
Invasive species arrive through many means.
People may intentionally introduce an invasive species for an agricultural or ornamental purpose. Once introduced, some of these non-native species escape their enclosures or cultivation and establish as a viable population. Accidental introductions usually result from contaminated freight, or from the movement of contaminated wood products (including shipping pallets, bracing and other dunnage), plants, or food products. The individuals or propagules (seeds, eggs, spores, or other biological material capable of propagation) of invasive species hitchhike in these shipments.
Invasive species move from one place to another using a variety of pathways. Some pathways can be natural, such as when a non-native species is carried by wind or ocean currents. Other pathways are human induced and can be intentional or unintentional.
Some common pathways include:
- Abandoned pets and ornamental plants;
- Ballast water discharged from ships;
- Importation of seeds, plants, fruits, and vegetables; and
- Soil brought in with nursery stock.
Why are invasive species successful in our environment?
Invasive Species are successful in the Lake George environment when they:
- Lack predators, pathogens, and diseases to keep population numbers in check.
- Produce copious quantities of seed with high viability.
- Have successful dispersal mechanisms that attract wildlife.
- Thrive on disturbance, and are very opportunistic
- Are fast growing.
- Are habitat generalists and do not have specific or narrow growth requirements.
- Some demonstrate allelopathy – they produce chemicals that inhibit the growth of other
plants nearby. - Have longer photosynthetic periods – they are first to leaf out in the spring and last to drop
leaves in autumn. - Alter soil and habitat conditions where they grow to better suit their own survival and
expansion.