2011 November Feature is Invasive Plants


Invasive Non-native Florida Plants

The forests of the southeastern United States are increasingly facing the impacts of non-native invasive species (plants, animals, and pathogens). Many invasive plants affect forest health, productivity, access and use, forest management costs, and limit species diversity on millions of acres of southeastern forests. These plants displace native plants and associated wildlife, and can alter natural processes such as fire regimes and hydrology. As foresters, landowners, and land managers we must be proactive and meet this issue head-on to maintain the health, function and long-term productivity of our forests.



Kudzu (Pueraria montana var. lobata) invasion in the Eastern United States. (Image courtesy of www.invasive.org)


Air potato (Dioscorea bulbifera) invasion in Central Florida mixed hardwood stand.


Japanese climbing fern (Lygodium japonicum) invasion in northwest Florida pine plantation.


Old World climbing fern (Lygodium microphyllum) invasion in Southeast Florida cypress stand. (Image courtesy of USDA ARS Photolab)


Cogon grass (Imperata cylindrica) invasion in pine stand, Central Florida.


Melaleuca (Melaleuca quinquenervia) invasion in Southwest Florida pine flatwoods.



Non-native invasive plants are essentially "Weeds in the Woods" (or in other natural areas). The two characteristics

NON-NATIVE:  Plants which are not originally from Florida/United States, these plants are often introduced intentionally or accidentally by human activity. The most common sources of plant introduction in Florida are: import for ornamental/horticultural purposes, introduction for agricultural purposes (forage, erosion control, etc.), and accidental introduction. Approximately 1/3 of the plant species growing on their own without cultivation in Florida are non-native.

INVASIVE: Invasive plants are plants which escape cultivation, become established in a forest or natural area, and start expanding and reproducing on their own. Once established, these plants often alter native plant communities, out-compete and kill native species, or otherwise affect natural ecosystems.


There are many reasons to be concerned about the expanding problem of invasive species. Whether your primary interest in forestry is timber production, aesthetics, recreation, wildlife, or a combination of many benefits, all aspects of forest management can be affected by these plant invasions. For example, approximately 46% of the federally listed threatened and endangered species in the United States are considered to be imperiled in part due to impacts of invasive species. Economists have estimated that across the globe, $3-5 trillion may be lost annually to the impacts and management of invasive species (this figure includes impacts by introduced plants and animals, diseases, agricultural weeds, and others).

Several of these species either possess the potential to, or have already begun impacting various forest product industries. An established example is that of Kudzu, which infests an estimated 7 million acres in the southeast, and costs approximately $500 million dollars in lost farm and timber production annually. The most recent example of this is the impact the Japanese climbing fern infestations have begun to have on the pine straw production industry in Florida. Pine straw producers have had to abandon leased pine stands in some cases where the Japanese climbing fern infestation made harvest of a clean and legally saleable product impossible.

As a state, Florida is at a high risk for invasion for many reasons. Our subtropical climate, the number and importance of our shipping ports, the extent and importance of the plant-based industries in the state, and the highly transitional population, couple with other factors to facilitate introduction, escape and spread of these problem plants. In Florida, approximately $30 million taxpayer dollars are spent annually on invasive plant management on natural areas and waterways.


Invasive plants are spread in many ways:

  • Humans through movement of equipment, and/or soil contaminated with seeds or roots
  • Wildlife (especially deer & birds)
  • Cattle
  • Water and wind

Forest managers need to be aware of how our actions can promote the spread of these plants. Many forestry techniques involve soil disturbance (e.g.. harvesting, site prep, planting) and alteration of the canopy (e.g.. harvesting) which affects sunlight and water penetration to the soil level, these activities may aid in the introduction or spread of these species on your property.


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This site was last updated 10/19/11