Prevent the Spread of Exotic Invasive Trees
Some, but not All Imported Trees Pose a Threat to the Landscape
Jun 18, 2009
Not all trees that are imported, or exotic are unwelcome or a threat to the ecosystem. Some exotics exist peacefully with native species. There are about 4,000 exotic plant species in the U.S., and of those only 1,000 actually pose a threat to the native plants.
European settlers brought hundreds of plants to North America from their home lands, for food, medicinal, ornamental, and other purposes, and not all are considered harmful and pose no threat to ecosystems (take apple trees, for example, as well as wheat, oats, etc.).
Invasive Exotic Trees are Aggressive
“Invasive exotics become a problem due to their aggressive invasive traits,” said Dave Moorhead, Ph.D. a Professor of Silviculture at the Warnell School of Forest Resources in Tifton, GA, which put together the Invasive.org website.
Most invasives are precocious and abundant seed producers, adaptable to a wide variety of sites, soils and drainage; they may also reproduce vegetatively, and may have properties that inhibit native species.
“These invasives generally displace native vegetation which can alter wildlife habitat characteristics…and impact plant & animal diversity,” said Moorhead.
Keeping these exotic invasive plants in check is expensive. Each year, the National Park Service and the Fish and Wildlife Service spends between 2 and 10 million dollars on controlling exotic plants. Agriculture, forestry, range lands and roadways management industries spend billions of dollars on managing exotic invasives.
Tips to Prevent the Spread of Exotic Invasive Trees
While not all exotics pose a threat, one never knows what can overwhelm a native species – and introductions of exotic plants and trees continue today because of population growth, travel and trade (some seeds actually come in inadvertently through shoes, clothing and luggage).
To help prevent the spread and growth of exotic invasive trees in the landscape, follow these tips:
- Try to prevent disturbance to natural areas. Don’t clear out native vegetation, or plant non-native plants or trees.
- Become aware of the hazards of planting invasive exotic trees in the yard, for landscaping, or for land restoration or erosion control projects.
- Use trees native to the region as much as possible, or use exotics that are not invasive.
- Control exotic invasive plants by removing them, or pruning them to prevent flowering and dispersing seeds. Take care not to spread seeds & fruits while doing removal or maintenance work on trees.
- Ask nurseries and garden shops not to sell invasive trees. Provide them with information (such as this article), and ask for non-invading native or exotics as alternatives.
- Be aware that land use changes (shifting from agriculture to fallow fields), site disturbances (creating bare ground, flood events etc.) can create favorable seedbeds for these & other invasives to gain a start in a habitat.
- Work with your local government to encourage the use of native plants in urban and suburban landscapes. You can provide them a list of attractive, non-invasive locally native alternatives.
For more information about exotic invasive trees visit:
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