The Ecological Effects of Off-Road Vehicles

“We’re seeing more and more erosion, water degradation, and habitat destruction . . . . And those are just some of the impacts [of off-road vehicles].” -- Forest Service Chief Dale Bosworth, Earth Day 2003-- Off-road vehicles erode and compact soils, destroy vegetation, and disturb the flow of the water and nutrients on which living things depend. This fact sheet will describe some of these undesirable impacts of off-road vehicles. Erosion and Compaction of Soil · The US Geological Survey found that virtually all types of soils are vulnerable to off-road vehicle damage after examining more than 500 soils at more than 200 sites (Schubert and Associates, 1999). · Some soils damaged by off-road vehicles require decades or centuries to recover (Belnap, 2003). · Because of their weight, off-road vehicles compress and compact soil, altering its ability to absorb and retain water and nutrients (e.g., Dregne, 1983). · Motorized vehicles decrease soil fertility by harming the microscopic organisms that otherwise would break down the soil and produce nutrients (e.g., Wilshire et al., 1977). · By compacting the soil and concentrating the surface flow of water, off-road vehicles increase erosion (e.g., Misak et al., 2002). · According to a study conducted in Appalachia, off-road vehicle use resulted in erosion that washed over 440 pounds of soil off every 67 feet of motorized route (Sack and deLuz, 2003). Erosion like this can greatly reduce soil fertility and add sediment to streams, degrading water quality and fish habitat. Damage to Native Vegetation · Off-road vehicles crush vegetation and root systems, killing seedlings and changing the composition of the forest (e.g., Cole and Bayfield, 1993). · Many sensitive plant species have the potential to go locally extinct in areas of high ATV use (Stensvold, 2000; Brown and McLachlan, 2002). · After only one pass by a snowmobile, over 78% of saplings were damaged, according to a study; 27% of them seriously enough to kill them (Neumann and Merriam, 1972). Spread of Weeds · Vehicles traveling on roads and routes spread weed seeds. Off-road vehicles are cited as the key source of the spread of invasive and noxious plants in the western United States, affecting an estimated 4,600 acres of public land daily (U.S. Department of Interior, undated). · Roads and off-road vehicles are chief threats to the invasion of exotic weeds in the roadless areas that provide refuge to native species (Gelbard and Harrison, 2003). · A study in Montana found that a single all-terrain vehicle (ATV) can disperse more than 2,000 knapweed seeds over a ten-mile radius (Montana State University Extension Service, 1992). A Wisconsin study surveyed sixty 100-meter segments of off-road vehicle routes and found at least one exotic plant along 88% of those segments (Rooney, in preparation). Pollution of the Air, Water, and Ground · Yellowstone National Park found that the two-stroke engines of snowmobiles dump 25% of their gasoline and oil unburned into the environment (U.S. Department of Interior, 1995). Snowmobiles account for 35 to 68% of carbon monoxide and 68 to 90% of hydrocarbons released annually in the park (U.S. Department of Interior, 2000). · The two-stroke engines of most off-road vehicles pollute the air, water, and ground with several known human carcinogens (U.S. Environmental Protection Agency, 1994). · Pollution from off-road vehicles can poison the plants and impede photosynthesis, weakening plants to disease and inviting invasion by exotic species (Shaver et al., 1988).

Impacts of Off-Road Vehicles and Roads on Wildlife

The negative effects of ATVs, snowmobile, and other off-road vehicles on wildlife are well documented. Most studies cite habitat loss as a primary concern, although there are a number of impacts. Roadkill - Collisions and impact induced mortality is one of the most apparent effects of off-road vehicles on wildlife populations. · Direct impact by an off-road vehicle will kill most animals (Rosen and Lowe 1994). Small animals are especially vulnerable (Wilkins 1982). Loss of habitat - Soil erosion, vegetation loss, introduction of exotic species, and fragmentation (carving habitat into smaller pieces) can all lead to significant habitat degradation. Cumulatively, these impacts can reduce the quality of entire terrestrial and aquatic ecosystems. · Habitat fragmentation reduces the suitability and availability of habitat for plants and animals, and has been cited as the primary factor threatening populations of black-tailed prairie dogs, boreal owls, flammulated owls, and other sensitive animals (Muller et al. 1992) · In desert ecosystems, ATVs can collapse lizard’s burrows causing direct mortality and loss of habitat (Stebbins 1974). · Personal watercraft (PWC, jet skis and WaveRunners) create waves that cause shoreline erosion and loss of marsh habitat (Dayton and Levin 1996). · Snowmobile trails can invite competition between species in places where they would not naturally co-exist such as coyotes intruding into lynx habitat (Bunnell et al. 2004). Increased disturbance and stress - Disturbance to wildlife can result in increased energy expenditure and reduction of reproduction in wildlife. · Noise and disturbance from off-road vehicles can result in a range of impacts for a number of species including altered movement patterns (e.g., Wisdom et al. 2004), avoidance (Janis and Clark 2002), and disrupted nesting activities (e.g., Strauss 1990). · With freezing temperatures and deep snow, winter can be the most trying time of the year for wildlife in temperate regions. Disturbance from snowmobiles can add additional stress at this critical time of year. Snowmobiles have been shown to disturb and create an energy cost for caribou (Fancy and White 1985), muskoxen (McLaren and Green 1985), deer (e.g., Moen et al. 1982), and elk (Creel et al. 2002). · Many carnivores will use snowmobile routes because the packed snow is easier to travel over, but they can also suffer stress from snowmobile harassment (Creel et al. 2002), and have a higher risk of being illegally shot or run over (Claar et al. 1999). Additionally, carnivores may follow snowmobile routes into less remote areas where there is a greater risk of conflict with humans. · While den abandonment by grizzly bears has been rarely documented because of snowmobiles (Linnell et al. 2000), as the off-route capabilities of snowmobiles has increased, so has the potential for disturbance (Hilderbrand et al. 2000). · The ability of PWCs to travel at high speeds in very shallow water has a great potential to disturb wildlife, especially breeding birds (e.g., Rogers and Schwikert 2002 ). · Anecdotal reports suggest that PWC use resulted in nest abandonment of loons in Montana (Hamann et al. 1999) and disturbance of brown pelicans and osprey in Florida (Jenkins 2002). · Further accounts have seen PWCs separate harbor seal pups from mothers, stampede seals and sea lions, and harass sea otters (Jenkins 2002). Increased poaching and harvest – Off-road vehicles can impact wildlife by increasing the number of humans in the backcountry where animals seek refuge · There have been increased reports of ATV hunters taking illegal “flock shots” at running pronghorn antelope from long ranges (Canfield et al. 1999). · Growing use of off-road vehicles can increase the trapping of pine marten, fisher, and wolverine (Weaver 1993). · Wolves often travel on off-road vehicle routes where they risk increased poaching pressure (Boyd and Pletscher 1999). Grizzly bear are also at risk from poaching on ATV routes and avoid open roads (Mace et al. 1996).

Impacts of Off-Road Vehicles and Roads on Hunting and Fishing

“An influx of ATV use in hunting is helping to destroy the ethical and cultural values of hunting, bringing the factory into the field and diminishing the love and appreciation of wildlife and wild places that come from hard work and effort.” --Dave Stalling, President, Montana Wildlife Federation-- Off-road vehicles harm fish and game species directly and indirectly through habitat destruction, roadkill, behavior alteration and increased stress. Millions of Americans enjoy hunting and fishing opportunities on public lands. Hunters and anglers, with their passion for protecting fish and game can play a crucial role in limiting motorized recreation on public lands. Hunting - Roads and off-road vehicle activity threatens wildlife and wildlife habitat through direct collision, noise pollution, increased stress levels, destruction of food and forage, and habitat loss. · It has been well documented that there is increased elk mortality rates in areas of high road density than areas with few roads (e.g., Unsworth 1993, McCorquodale et al. 2003). · Gratson and Whitman (2000) found increased hunter success in unroaded (25%) and reduced open-road density (24%) than roaded areas (15%). · Using a sample of 78 radio-collared elk, Lepitch and Zager (1991) created a model showing that closing roads increased the age structure to include more mature bull elk. Their model also found that closing roads would double the sex ratio to 20 bulls per 100 cows; in roadless areas, there would be upto 35 bulls per 100 cows. · ATVs have also been found to disturb elk. One study found that elk moved twice as far from ATV disturbance than pedestrians (Vieira 2000). Wisdom et al. (2004) found that elk moved when ATVs pass within 2,000 yards but tolerate hikers within 500 feet. Further the study found that elk walked away from hikers but ran from ATVs. · Snowmobiles have been shown to disturb and create stress for caribou (Fancy and White 1985), muskoxen (McLaren and Green 1985), deer (e.g., Moen et al. 1982), and elk (Creel et al. 2002). · Personal watercraft have been found to disturb feeding and nesting areas of several game bird species potentially reducing their populations (e.g., Burger 1998, Rodgers and Schwikert 2002). Fishing - Off-road vehicles emit millions of gallons of gasoline and oil into streams, rivers, and lakes. Roads and trails destabilize soil and cause erosion. Eroded soil eventually enters streams and rivers, dramatically reducing the quality of native fish habitat. Additional impacts include roads that disconnect streams (due to missing or poorly-designed culverts), restricting or preventing access to spawning habitat. · Sediment runoff from roads and trails ends up in streams and rivers, where it can cover fish eggs and inhibit nest building. Runoff also alters the natural flow of water that rinses waste and oxygenates the spawning nests. (Newcomb and MacDonald 1991). · Five native subspecies of cutthroat trout—the Yellowstone, fine-spotted, westslope, Bonneville, and Colorado cutthroat—as well as the fluvial Arctic grayling and the Kendall Warm Springs dace, are considered to be at risk in the Greater Yellowstone ecosystem, in part due to sedimentation and habitat loss caused by off-road vehicle use (www.greateryellowstone.org). · Personal watercraft emit pollutants such as benzene, toluene, and xylene, all of which settle in estuarine and shallow water ecosystems where fish eggs, larvae, algae, crab, shrimp, and other crustaceans live. Studies have found adverse effects on rainbow trout and insect communities (Johnson, 1998; Tjärnlund, et al. 1995). · Toxic discharge from personal watercraft is made 50,000 times worse by ultraviolet rays, killing plankton and other small water organisms which impact the entire aquatic food chain. · Road decommissioning has been shown to reduce sediment, which should increase the quality of fish habitat in streams below. Bull trout populations were found to increase following road recontour and culvert removals on the Kootenai National Forest. After five years of monitoring, Wegner (1999) reported a 48 % decline in fine sediments and a 16 % increase in bull trout redds.

Impacts of Off-Road Vehicles and Roads on Special Ecosystems

“Off-road vehicles have damaged every kind of ecosystem found in the United States: sand dunes covered with American beach grass on Cape Code pine and cypress woodlands in Florida; hardwood forests in Indiana; prairie grasslands in Montana; chaparral and sagebrush hills in Arizona; alpine meadows in Colorado, conifer forest in Washington, arctic tundra in Alaska.” --from “Off-Road Vehicles on Public Lands” by the White House Council on Environmental Quality-- Wetlands and Aquatic Ecosystems - Runoff of nutrients, chlorides, heavy metals, and organic chemicals from motorized travel is toxic to aquatic organisms and can contaminate drinking water. Additionally, changes in the hydrology and increases in stream sedimentation because of roads and trails can degrade wetland and aquatic habitat as well. · In Yellowstone National Park, snowmobiles release about 20 tons of Hydrocarbons (HC) and 54 tons of Carbon Monoxide (CO) into the park on a peak day (USDOI 2000). Automobiles in comparison omit 2.5 and 17.9 tons of HC and CO respectively on a busy summer day (USDOI 2000). · As much as 30% of fuel is unburned in two-stroke engines. With an average of 60,000 snowmobile visits per year (USDOI 2003), three tanker trucks worth of gas/oil mixture is being released into the air and snowpack each year. Furthermore, it has been estimated that running a two-stroke engine seven hours produces more air pollution than running a modern car for 100,000 miles on a road (CEPA 1999). · Two-stroke engines (including personal watercraft) on Lake Mead National Recreation Area (Arizona/Nevada) were estimated to discharge over 27,000 gallons of unburned fuel into the lake per day on a peak summer weekend (USDOI 2002). · Drinking water can also be quickly contaminated by PWC use. For example, operating a two-stroke engine for one hour makes 11,000m3 of water undrinkable (Jüttner et al. 1995). · Road construction near rivers and streams is often accompanied by the creation of diversions, channels, culverts and bridges—all of which can affect water flow patterns, increase sediment loads, and alter the shape the adjacent streambed. These changes can reduce fish populations and degrade aquatic habitat (Gucinski et al. 2001). Desert Ecosystems - Naturally sparse in vegetation, deserts are highly sensitive to roads and off-road vehicle use. At the same time, the visually open terrain draws enormous off-road vehicle use in deserts. · Off-road vehicles destroy the living soil crust upon which plants depend for stability and fertility—making growth virtually impossible. The crust can take several hundred years to recover (Belnap 2003). · Almost all of the 24 species listed as endangered or threatened in the California Desert Conservation Area—including the desert tortoise, bighorn sheep, desert pupfish, Inyo California towhee, and arroyo toads—are threatened by off-road vehicle use and roads (www.biologicaldiversity.org). · Off-road vehicle use negatively affect wildlife including collapsing fringe-toed lizard burrows (Stebbins 1974), reducing habitat of tortoises (Bury and Luckenbach 2002), and increasing susceptibility of mortality of flat-tailed lizards from vehicle collisions (Nicola and Lovich 2000). Tundra Ecosystems - This ecosystem is characterized by a lack of trees where portions of the soil remain permanently frozen. They are fragile, delicately balanced environments where roads and off-road vehicles exacerbate already harsh conditions for plant and animal populations. · Tundra roads are raised above the ground and act as dams blocking or altering natural water flows (Walker et al. 1987) · Most roads in Alaska are dirt or gravel and dust blown into the adjacent areas alters melting rates, soil chemical composition, vegetation, and below-ground nutrient cycling (Walker and Everett 1987; Auerbach et al. 1997). · Roads have been found to negatively impact caribou herds by decreasing their density (Nelleman and Cameron 1998), acting as barriers to movement (Whitten and Cameron 1983), and creating avoidance of preferred habitat (Nelleman and Cameron 1996).