Off-Road Vehicle Impacts on Sand Dune and Sandy Beach Habitats

Sand dunes and sandy beaches contend with surf spray, storms, wind, and other extreme conditions. These coastal areas also face unique challenges related to population growth, climate change, and urban development and sprawl – more than half the U.S. population lives in coastal areas. And while these habitats and the flora and fauna that inhabit them are robust, they are also vulnerable to the impacts of human recreation and development.  In fact, the coastal zone is home to more than one third of U.S. federally listed species.  In this paper, I review the negative impacts on sand dunes and sandy beach habitats from off-road vehicles (ORVs) including cars, trucks, and other vehicles driven off the main road. 

Godfrey and Godfrey (1981) found ORV traffic to have substantial negative impacts on dune plant species. They subjected three plant communities to 50 vehicle passes. Not only were plants trampled and damaged by the traffic, but they were also slow in recolonizing ORV tracks after traffic had ceased. Some quickly growing plants, such as those that specialize in colonizing new areas, were able to recover relatively rapidly. Other slow growing plants and those that reproduce by seed did not recover as quickly. For example, lichen cover was found to be extremely fragile. 

ORVs also churn up and dry out the organic drift lines (the high point of material deposited by waves). Plant seeds deposited at these organic drift lines often develop into mature plants over time, but Godfrey and Godfrey (1981) found that ORV traffic trampled seedlings and made the soil unsuitable for growth, thereby retarding the natural cycle of plant colonization and the formation of foredunes (a ridge of irregular sand dunes partially covered with vegetation).  Rickard et al. (1994) examined the impact of ORVs on vegetation growth by comparing two dune sites in South Africa: a pioneer vegetation zone and a climax shrubland. Both sites were damaged by ORV traffic, but the pioneer vegetation was able to rapidly recolonize while climax shrubland was much slower in its regrowth. An important consideration for these areas is once vegetation has been killed by ORV traffic the 

Schlacher and Thompson (2008) found beach traffic caused widespread and significant physical disturbance to sandy beaches: large areas of the beach were rutted by vehicle tracks, ORVs compacted and displaced significant volumes of sand down shore, and in general, traffic disturbed the drift line, foredunes, and backshore (area of shore lying between the average high-tide mark and the vegetation). 

Anders and Leatherman (1987) examined ORV impacts on the coastal foredunes of Fire Island in New York. Here beach grass assists in promoting sand accumulation; this accumulation creates a broad foredune that helps dissipate storm wave energy. In ORV impacted areas the beach grass was eliminated, thereby inhibiting sand accumulation. The end result was a steeper foredune profile that did not dissipate wave energy as effectively as the natural dune face, creating a greater potential for beach erosion (Anders and Leatherman, 1987). 

Dune and beach dwelling birds tend to nest in or around the dunes above the high water mark. Since most beach traffic is concentrated at or below the high water mark, nests may be relatively safe from vehicle disturbance. However, once chicks hatch, they move from their nests to the intertidal zone where they feed and roost. This puts them directly in the path of ORV traffic. Both Watson et al. (1996) and Melvin et al. (1994) found the feeding and roosting behavior of various bird species [whitefronted plovers (Charadrius marginatus), damara terns (Sterna balaenarum), African black oystercatchers (Haematopus moquini), and piping plovers (Charadrius melodus)] to coincide with the main ORV driving areas. Specifically, Melvin et al. (1994) found that ORV use, even at very low levels (5-10 vehicle passes per day), is enough to threaten unfledged piping plover chicks and adults during brood rearing periods. 

ORV traffic negatively impacted Loggerhead turtle (Caretta caretta) hatchlings (Hosier et al. 1981). ORV ruts created difficult terrain for turtle hatchlings to negotiate on their journey from nest to sea. On flat, water-smoothed beach surfaces turtles could orient themselves toward the surf phototactically (using light intensity in order to determine the way to the water), but on a bumpy terrain turtles found their way toward the water less directly. This time-consuming, indirect route left turtles more exposed to the elements and vulnerable to predators. 

Invertebrates make up a large part of the fauna population of sandy beaches (Schlacher et al. 2008a). In monitoring the overlap between invertebrate habitat zones and areas of ORV traffic, Schlacher and Thompson (2007) found the majority of the invertebrates they sampled (65%) lived in areas of vehicle traffic. Ghost crabs (Ocypode cordimana) construct and live in beach burrows during the day and are mostly active at night. Schlacher et al. (2007b) conducted a number of experiments to evaluate ORV impacts on crab populations. When crabs left their burrows at night there was a high mortality rate due to night ORV driving. They found beaches with fewer ORVs had higher crab populations. In addition, crabs buried farther below the sand were more protected from crushing than those shallowly buried. 

Finally, the surf clam (Donax deltoids) was also adversely affected by ORV traffic on beaches in Australia. As the number of vehicle passes increased, so too did the number of clams killed (Schlacher et al. 2008). 

Any management strategy considered or implemented must take into account myriad factors from environmental to recreational to economic. From a conservation perspective all ORV traffic should be eliminated from sand dunes and sandy beach ecosystems. In the event this is not feasible, other options are available that can mitigate ORV impacts.  Mitigation strategies include: seasonal closures during bird breading periods; only allowing riding on designated routes; limiting driving during times of high water; and prohibiting night beach driving especially on beaches where there is night activity among fauna.  There should also be mandatory vehicle registration and educational programs.  And in areas with damage, sand dunes should be rehabilitated and stabilized. 

A study by Celliers et al. (2004) outlined an integrated coastal management system to determine which coastal areas were suitable for ORV use. Their management strategy concentrated ORV use in small pockets, leaving other areas of the coast free from harmful impacts. Celliers et al. (2004) developed seven attributes that determine if areas are too vulnerable to allow ORV use. This system gives managers baseline criteria that unequivocally protect areas from ORV use. Though this system was applied to a specific area of South Africa, it can be modified and used as a model for coastal land managers in other parts of the globe. 

Off-road vehicle use on sandy beach and sand dune habitats exists within economic, environmental, and social contexts.  Off-road vehicle recreation has economic and social benefits and drawbacks.  It also negatively impacts the flora, fauna, and physical landscape of these areas. It is essential that integrated, thoughtful, and site-specific management programs be implemented to mitigate and prevent ORV impacts to sand dune and sandy beach ecosystems.  

— Beth Gibson is a graduate student in Environmental Studies program at the University of Montana. 

Anders, F. & S. Leatherman. 1987. Effects of off-road vehicles on coastal foredunes at Fire Island, New York, USA. Environmental Management 11(1): 45-52. 

Celliers, L., T. Moffett, N.C. James, & B.Q. Mann. 2004. A strategic assessment of recreational use areas for off-road vehicles in the coastal zone of KwaZulu-Natal, South Africa. Ocean and Coastal Management 47: 123- 140. 

Godfrey, P. & M. Godfrey. 1980. Ecological effects of off-road vehicles on Cape Cod. Oceanus 23: 56-67. 

Hosier, P., M. Kochhar, & V. Thayer. 1981. Off-road vehicle and pedestrian track effects on the sea-approach of hatchling loggerhead turtles. Environmental Conservation 8(2):158-161. 

Melvin, S., A. Hecht, & C. Griffin. 1994. Piping plover mortalities caused by off-road vehicles on Atlantic coast beaches. Wildlife Society Bulletin 22(3): 409-414. 

Rickard, C.A., A. McLachlan, & G.I.H. Kerley. 1994. The effects of vehicular and pedestrian traffic on dune vegetation in South Africa. Ocean and Coastal Management 23: 225- 247. 

Schlacher, T., J. Dugan, D. Schoeman, M. Lastra, A. Jones, F. Scapini, A. McLachlan, & O. Defeo. 2007a. Sandy beaches at the brink. Diversity and Distributions 13: 556-560. 

Schlacher, T., L. Thompson, & S. Price. 2007b. Vehicles versus conservation of invertebrates on sandy beaches: quantifying direct mortalities inflicted by off-road vehicles on ghost crabs. Marine Ecology 28: 354-367. 

Schlacher, T. & L. Thompson. 2007. Exposure of fauna to off-road vehicle traffic on sandy beaches. Coastal Management 35: 567-583. 

Schlacher, T. & L. Thompson. 2008. Physical impacts caused by off-road vehicles to sandy beaches: Spatial quantification of car tracks on an Australian barrier island. Journal of Coastal Research 24: 234-242. 

Schlacher, T., L. Thompson, & S. Walker. 2008. Mortalities caused by off-road vehicles (ORVs) to a key member of the sandy beach assemblages, the surf clam Donax deltoides. Hydrobiologia 610: 345-350. 

Watson, J. J., G. I. H. Kerley, & A. McLachlan. 1996. Human activity and potential impacts on dune breeding birds in the Alexandria coastal dunefield. Landscape and Urban Planning 34:  315-322.