What is an Invasive Species?
The United States has an overabundance of invasive species; including animals and plants that have been introduced from other parts of the world. These non-native species threaten vulnerable ecosystems and biodiversity by crowding out or eliminating native species. They can be introduced by ships, wood products, packing material, or deliberately by humans. Invasive Species are usually defined as non-native species whose introduction does or is likely to cause economic or environmental destruction, or harm to human health. By know we all know that there are some downsides to having non-native plants spreading across an environment. The spreading can cause risk to many native plants and animals, which can potentially cause extinction. One of the best ways to prevent the spread of invasive plant species is to stop them from growing in the first place. By identifying the plants in current landscapes or gardens that are not native, and removing them, can help prevent any spread of these non-native species in the future. When buying new plants at a nursery it is especially important to ask or find out which plants are native to your area and which are not. All it takes is just a few simple questions to be asked, which can potentially help save an environment in the long-term. It is much easier to remove a single invasive plant before it gets the chance to take over and reproduce more of its kind.
How does a species become invasive?
Invasive species typically colonize and populate rapidly. They can be tolerant of multiple habitats, compete aggressively for valuable resources such as food, water, and sun, and they lack natural enemies that help support biodiversity.
Invasive Species in the Pacific Northwest
Morning Glory – perennial vine, seed remains viable for 50 years
Lesser Celandine – deciduous aggressive ground cover
Pokeweed – perennial with dark berries toxic to humans
English Ivy – evergreen woody vine, can pull down trees
English Holly – evergreen thicket-forming, up to 50 feet tall
Scotch Broom – semi-evergreen shrub with yellow pea flowers
Purple Loosestrife – aggressive perennial with dark pink flowers
Traveler's Joy – deciduous twining vine with white spring flowers
Knotweeds – perennial with heart shaped leaves, thickets 10 feet tall
Spurge Laurel – evergreen shrub, berries and sap toxic
Tree of Heaven – deciduous tree 80 feet tall with yellow flower
Butterfly Bush – deciduous shrub 10 feet tall with flowering heads
Himalayan Blackberry – semi-evergreen, thorny canes more oval than blackberry
English Laurel – evergreen shrub up to 30-foot hedge
Yellow Flag Iris – perennial up to 4 feet tall, forms dense mats in wetlands
Garlic Mustard – biennial with flowers and seeds in second year
Lesser Celandine – deciduous aggressive ground cover
Pokeweed – perennial with dark berries toxic to humans
English Ivy – evergreen woody vine, can pull down trees
English Holly – evergreen thicket-forming, up to 50 feet tall
Scotch Broom – semi-evergreen shrub with yellow pea flowers
Purple Loosestrife – aggressive perennial with dark pink flowers
Traveler's Joy – deciduous twining vine with white spring flowers
Knotweeds – perennial with heart shaped leaves, thickets 10 feet tall
Spurge Laurel – evergreen shrub, berries and sap toxic
Tree of Heaven – deciduous tree 80 feet tall with yellow flower
Butterfly Bush – deciduous shrub 10 feet tall with flowering heads
Himalayan Blackberry – semi-evergreen, thorny canes more oval than blackberry
English Laurel – evergreen shrub up to 30-foot hedge
Yellow Flag Iris – perennial up to 4 feet tall, forms dense mats in wetlands
Garlic Mustard – biennial with flowers and seeds in second year
Corrective Measures
If a non-native plant species has already spread there are ways to correct the areas that have already been taken over. The measures to remove invasive species are not always easy and cheap, but should be done along with long-term preventative changes. There three possible ways of taking control over an invasive species: manually, chemically and biologically.
Manual Methods of Control
Removing the invasive species in a manual way usually results by physically digging and removing the roots of the invasive plant itself. All of the root system and stems must be taken out of the ground in order to prevent any further growth form occurring. This is because most plants have meristem cell tissues, which are cells that can divide and grow a whole new plant on their own, if given the opportunity. This means that all of the non-native plant in its entirety (roots/stems) must be removed in order to prevent future spouting of that plant again. This type of control method may require treatment to be done multiple times before the species is completely gone. Since this method requires much persistent work it is not always economically feasible.
If the invasive plants can be attended to frequently, then cutting or mowing them down often is another possible short-term alternative. Except that this means the invasive plant is still alive and in the way of the native plants. Eventually the non-native plants will need to be taken out for good.
Another method is suffocation. By simply placing several layers of either thick UV-stable plastic or another impenetrable barrier to cover over the infestation, and leaving it there for a long period of time, eventually the invasive plants will die and new native plants can be planted in their place. This method may not look the best, but it is cheap, easy, and doesn’t add chemicals into the soil!
Sometimes with the right permits and safety precautions, burning the invasive species can be a good option. This method works to remove large masses of a non-native species, but fire is hard to control. This means a lot of plants will burn and die, not just the non-native ones. The burning method is not suggested for everyone, but is a control technique that can be used if local ordinances allow.
If the invasive plants can be attended to frequently, then cutting or mowing them down often is another possible short-term alternative. Except that this means the invasive plant is still alive and in the way of the native plants. Eventually the non-native plants will need to be taken out for good.
Another method is suffocation. By simply placing several layers of either thick UV-stable plastic or another impenetrable barrier to cover over the infestation, and leaving it there for a long period of time, eventually the invasive plants will die and new native plants can be planted in their place. This method may not look the best, but it is cheap, easy, and doesn’t add chemicals into the soil!
Sometimes with the right permits and safety precautions, burning the invasive species can be a good option. This method works to remove large masses of a non-native species, but fire is hard to control. This means a lot of plants will burn and die, not just the non-native ones. The burning method is not suggested for everyone, but is a control technique that can be used if local ordinances allow.
Chemical Control Methods
The chemical methods of control such as herbicides are in fact probably the most commonly used method, as it is quick and easy, but there is a big concern with this method. Herbicides can do a great job of wiping out a whole colony of plants in a short amount of time, but the effects to the soil and environment afterwards is not appealing. There are too many downsides to this method that can have short or long-term effects on the environment afterwards. The soil after an invasive species has been killed by herbicides is not always the best for the native plants. Most herbicides are not selective as to which plants are killed by the chemicals, which means that any native plants that may have been fighting to survive, next to the invasive ones, will most likely die as well.
Biological Methods of Control
The biological way of controlling a non-native species is by learning about what diseases or predator insects typically target the non-native plants in their real homeland, and applying those appropriate measures to the unwanted plants. This method is not commonly used, as there are chances that the applied method can also attack the native plants as well as the invasive ones. This method is still being fine-tuned by scientists and could possibly produce nice results in the near future.
Disposal of the Invasive Plants
Proper disposal of the invasive plants is vital to the process of removing them completely and not having a regrowth occur. Since plants have a tendency for regrowth from almost any part of them, it makes getting rid of them tricky. The most efficient way to dispose of the invasive plants is to burn them. This can be done by taking the appropriate safety precautions and making a burn pile on your own, or taking the remnants to your local landfill and having them burn it along with other debris. Another possible method for disposal is to have the invasive plants completely dry out on concrete or asphalt until there is no chance for regrowth to occur, then dispose of the remnants in the trash.
Costs Involved With Removing Non-native Species of Plants
Personal Level
Removing non-native species is a costly issue. The best way to deal with imported/invasive species is prevention and early detection. If you’re beyond that, you are looking at a lot of hard work or a lot of money to remove them. Many of these plants have rhizomes (bamboo, yellow flag iris, etc.) and can cost thousands to have them professionally removed and have barriers put in place to prevent them from recurring.
National Level
It costs America approximately $120 BILLION each year to control invasive species and clean up the damage caused by them. Over 100 million acres suffer from infestations of invasive plants.
Invasive species cause a large issue for waterways. Aquatic invasive plants in the US cost around $100 million each year.
Global Level
This is not just an issue in the US. Globally, 5% of the world’s economy is spent on the cost of impacts and control efforts from invasive plant species.
Other Costs
While these dollar estimates are large, the vast effects of invasive species are even larger.
These costs include money spent in wildfire control, as invasive species typically cause wildfires to burn faster and cause more damage. Invasive species also cause more dollars to be spent post-flooding, as they block creeks and other waterways, causing flooding to increase in likelihood and magnitude. The invasive plants in waterways also cause financial ruin on commercial and tourism industries by blocking waterways. In addition, they cause a decrease in oxygen supply to the fish in these waterways, killing them.
This is not just an issue in the US. Globally, 5% of the world’s economy is spent on the cost of impacts and control efforts from invasive plant species.
Removing non-native species is a costly issue. The best way to deal with imported/invasive species is prevention and early detection. If you’re beyond that, you are looking at a lot of hard work or a lot of money to remove them. Many of these plants have rhizomes (bamboo, yellow flag iris, etc.) and can cost thousands to have them professionally removed and have barriers put in place to prevent them from recurring.
National Level
It costs America approximately $120 BILLION each year to control invasive species and clean up the damage caused by them. Over 100 million acres suffer from infestations of invasive plants.
Invasive species cause a large issue for waterways. Aquatic invasive plants in the US cost around $100 million each year.
Global Level
This is not just an issue in the US. Globally, 5% of the world’s economy is spent on the cost of impacts and control efforts from invasive plant species.
Other Costs
While these dollar estimates are large, the vast effects of invasive species are even larger.
These costs include money spent in wildfire control, as invasive species typically cause wildfires to burn faster and cause more damage. Invasive species also cause more dollars to be spent post-flooding, as they block creeks and other waterways, causing flooding to increase in likelihood and magnitude. The invasive plants in waterways also cause financial ruin on commercial and tourism industries by blocking waterways. In addition, they cause a decrease in oxygen supply to the fish in these waterways, killing them.
This is not just an issue in the US. Globally, 5% of the world’s economy is spent on the cost of impacts and control efforts from invasive plant species.
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