Potential Adverse Impacts of Recreation Activities on Forested and Aquatic Ecosystems and Where They Are Located
Depending on the type and intensity of recreation use, the type and fragility of a forest site, and the type and level of site management, recreation in forested ecosystems impacts soil, water, vegetation, and animal life. To our knowledge, there is no comprehensive regionwide assessment of the impacts of recreation on forests. Such an undertaking would be enormously complicated and costly. There are only a few isolated studies of impacts, and these are primarily limited to trails, rivers, and campgrounds on public land. The most comprehensive treatment of recreation use found dealt with wildlife (Knight and Gutzwiller 1995). Nevertheless, recreation can significantly affect natural systems, such as forests, in the following ways:
- Soils—Repeated foot, horse, motor vehicle, or other recreation traffic can compact many types of soil, especially those with high clay content as is prominent in the Piedmont and mountain areas of the South. A heavy volume of traffic also can loosen topsoil and reduce vegetative cover, inviting erosion. Further, chemicals used in site management or by recreationists can change the chemical properties of soil.
- Water—Surface water in streams and in impoundments, groundwater, and runoff from precipitation are all potentially impacted by recreation use and management. Chemicals, such as herbicides, used on or near shorelines or used directly in water to control aquatic vegetation will almost certainly alter the chemical and biological properties of water. Humans coming into contact with water can introduce high levels of bacteria. Recreation near or along shorelines also disturbs soils, diminishes the density and health of vegetation, and reduces populations of animals, especially amphibians and waterfowl. Heavy recreation traffic often causes high levels of sedimentation. Heavy traffic also can disrupt fish life patterns, including spawning. Overfishing interrupts balances among vertebrate and invertebrate species, both aquatic and terrestrial.
- Vegetation—Grasses, herbs, shrubs, trees, and aquatic vegetation all can be impacted by outdoor recreation. Recreation in developed sites mainly impacts the planted grasses, residual trees left for shade, and immediately surrounding woodlands. From a broad perspective, these impacts are relatively minor. There is also vegetative impact on and near trails caused by hiking, horseback riding, mountain biking, and motor vehicles. Crushing ground vegetation, breaking reachable herbal and woody vegetation, and exposure and damage to roots are the forms of damage usually encountered. Along roads, ground vegetation can be heavily impacted in unhardened areas by motor vehicles, and nearby sensitive plants can be impacted by exhaust emissions. Typically, vegetation along roads is not much impacted. Aquatic vegetation and vegetation along shorelines can be impacted by water disturbance and by wave action caused by boats. Persistent erosion and undercutting of shorelines is typical of Piedmont and mountain lakes. Native vegetation on a wide variety of settings can be cumulatively impacted by competition from exotic species planted or otherwise introduced as a part of recreation site management.
- Animal life—Terrestrial mammals, birds, insects, bacteria, subterranean animals, fish, and all other forms of animal life can be dramatically impacted by recreation use. The presence of recreation users influences animal behavior and animal habitat. Hunting of game animals alters their natural age and sex ratios. Horses and all-terrain vehicles have high potential for altering wildlife habitat. We will not attempt to list all the possible adverse effects of recreation on ecosystems. The main point is that recreation effects on the land are not benign. Ever-increasing use of forests and other natural systems will have increasing impacts (Knight and Gutzwiller 1995).
In figure 11.1, percentage of area in forest cover in southern counties is cross-indexed with outdoor recreation participation per 1,000 population based on data from the NSRE in 1995 (Cordell and others 1996, 1999). Recreation travel data indicate that the majority of outdoor recreation participation occurs within 50 miles of people’s residences, a distance approximately the same as the distance from the center of one county to the outer boundary of an adjacent county in the South (Cordell and others 1999). We have indexed reported participation from residence relative to percentage of resident and adjacent counties’ area in forest cover to identify counties with a high probability of heavy recreation pressure. In such counties, the level of forest cover and recreation participation are both high. The mapped index highlights counties where heavy recreation pressures on forest resources are anticipated. Counties with these conditions are identified as hotspots. Where there is little to no forest cover (for example, in an urbanized county) or little to no recreation demand, negligible pressures are likely occurring. Our focus is on counties with relatively abundant forest resources where moderately heavy to heavy recreation pressures are occurring. These counties we identify as hotspots, and mostly they are found in:
- South coastal North Carolina and coastal South Carolina, especially in the Charleston area;
- North coastal Florida, the Jacksonville area;
- Gulf coastal north Florida; coastal Alabama, Mississippi, and Louisiana, especially the New Orleans Delta area;
- The “Piedmont Crescent” running from north-central North Carolina to the Birmingham area in Alabama;
- South-central Mississippi, especially the Jackson area;
- The Ozark and Ouachita Mountains and the Little Rock, AR, area; and
- Northeastern West Virginia and western Virginia.
To address recreation pressures on aquatic systems, we use data from the National Resources Inventory (NRI) describing the acres of water bodies and wetlands. The NRI is conducted every 5 years by the Natural Resources Conservation Service. Figure 11.2 shows a number of areas with relatively abundant water and wetlands that also have heavy recreation pressures. The same approach of using data from resident and adjacent counties as explained above was used to identify counties with water and wetland resources under recreation pressure. Pressures on water bodies often are high because water is a very prominent draw for outdoor recreation. Counties that are hotspots and those with moderately heavy pressures include most of the coastline of the South from Virginia to Texas. Almost all of the Florida peninsula is coded as a water and wetland hotspot. Other areas include:
- Piedmont South Carolina;
- Northern Alabama;
- Northern Louisiana;
- Central Arkansas, especially the Little Rock area; and
- Isolated clusters of counties in east Texas, northeastern Oklahoma, western West Virginia, central Georgia, and western Tennessee.
