2009-06-18 / Community News

Controlling Invasive Plants

Invasive plants are one of the most significant natural threats to preserving historic landscapes and the wildlife that depend on native habitat to survive.

Non-native, exotic species often thrive in areas throughout the state. If left unchecked, they often spread over vast areas and eventually cover, eliminate or replace the native trees, grasses and shrubs. They also have very detrimental effects in our aquatic ecosystems, creating new challenges in controlling species on site and regulating the spread of these species.

The word "invasive" is usually defined as meaning intrusive, invading and offensive. To be invasive may imply that the organism has never occurred on a specific site or niche before or prior to its first introduction. Invasive plants are those that have a tendency to spread and invade healthy landscapes ultimately causing some kind of negative impact. Invasive plants are often best defined as "plants that do not stay where they are planted."

Most often we tend to think of invasive plants such as honey mesquite, huisache, common broomweed, ragweed, dewberry, macartney rose, Chinese tallow, prickly pear, and others. These plants will increase on the land and are looked at as pests which reduce carrying capacity of the land and sometimes alter land uses.

Invasive species have been introduced into Texas in many different ways. Little is currently known about how most invasive species made their way into the state. Initially, these plants could have been transfered here by a seed stuck on the clothing of early pioneers, a plant or seed dropped by a migrating animal, or as a contaminant in feedstuffs brought from Europe, Asia or Africa.

Plants from foreign countries are often purposfully planted for one purpose with realizing the damage the plant might do in the future. Who would have guessed

that Macartney rose from Japan, introduced in the 1850's as the "living fence" would now be a major invasive plant of pastures in the eastern half of Texas?

Or that wonderful introduced livestock forage grass named "Johnsongrass" would cost Texas taxpayers a mere $53 million in 1998 for chemical control on Texas roadsides alone?

Or that King Ranch bluestem, a noted grass useful in the recovery and protection of played-out farmland, would be the number one weed on roadsides in central Texas today?

The Chinese tallowtree, first introduced as an ornamental for landscaping, is now invading much of the area in southeast Texas, from pastureland to vacant lots. Tallowtrees are changing the coastal grassland prairie into a wooded thicket of limited value.

Most invasive plants do not provide quality food or much value to Texas' wildlife. Wildlife species are tied to a certain group of native plants which can serve as food, a source of water and shelter. Most native plants are also associated with a native animal or group of animals as part of their natural ecology.

The planting of many foreign plants or invasive plants in large landscape patches can further the current problems seen in Texas with wildlife and plant habitat fragmentation. Some invasive species can threaten the existence of native plants and animals and may even serve to cause human related problems. We should all promote native plant species and control the spread of invasive- non-native plants for the long term health of the environment.

If you would like to contact your local biologist, see our website at; http:// www.tpwd.state.tx.us/ wildlifebiologist.

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