Many plants can affect the ability of outdoorsmen to enjoy natural areas. Invasive plants, such as kudzu, English ivy and Japanese stilt grass can grow over trails and make them harder to follow and navigate through. Natural beauty is reduced by invasives. Many invasives can produce single species communities by displacing and killing native wildflowers, trees and shrubs.

Many invasive plants make hiking, camping, and other outdoor activities unpleasant. Exotic stinging needle, with its stinging hairs, and multiflora rose, with its sharp prickles, can take over camping sites, making it hard to find a good spot to camp. Giant hogweed and wild parsnip sap on skin can cause hyper photosensitivity and cause burns, blistering and skin discoloration. Spines on invasive thistles and prickles on wine raspberry can scrape skin and tear clothing. If traveling by horse or mule some invasives, such as beefsteak plant, can be poisonous to our four-legged companions.

Red imported fire ants, as anyone from the South knows, are extremely aggressive and have a powerful sting. Pustules that result from fire ant stings are irritating and can cause permanent scarring. Inadvertently disturbing a fire ant mound, by staking a tent or stepping on it, can be a very unpleasant experience for the disturber. Curious dogs or other four legged companions can easily become covered with fire ants.

Feral hogs can cause a wide variety of problems for outdoor enthusiasts in the South. Hogs are omnivores and will eat almost anything, including any food that you may leave uncontained and unattended. Hogs are wallowers and rooters; these activities can destroy natural beauty, sections of hiking and riding trails and camping sites. Feral hogs have also been shown to spread brucellosis to humans and livestock. While symptoms of a mild case of brucellosis can resemble the flu, severe infections can affect the central nervous system and the lining of the heart. There is currently no brucellosis vaccine available for humans.

West Nile virus was first detected in the United States in 1999 and is spread by infected mosquitoes. People that spend time around standing bodies of water or other areas with high levels of mosquitoes could be at risk of contracting this virus. People that contract West Nile virus usually have mild flu-like symptoms or no symptoms at all. However, if the virus enters the brain it can cause the brain and spinal cord to swell and can lead to death. There are no specific vaccines or treatments available for the virus. So far in 2008 there have been 236 reported cases and 2 deaths caused by West Nile virus in the United States.