Physical impacts caused by off-road vehicles to sandy beaches: Spatial quantification of car tracks on an Australian barrier island

Beach traffic can substantially modify the physical environment on sandy beaches. Vehicle impacts on beaches were quantified on North Stradbroke Island, a barrier island on the east coast of Australia where large volumes of recreational off-road vehicle (ORV) traffic are concentrated on two beaches (Flinders Beach and Main Beach). The distribution, density, and depth of vehicle ruts on these beaches were quantified during the peak holiday period around late December and early January 2005-06. The density of tyre tracks per meter of beach face ranged from 2.69 to 6.35 on Flinders Beach and from 2.38 to 8.06 on Main Beach, and substantial areas (54-61%) of each beach were covered withy tyre tracks up to a maximum of 90% in some areas. ORVs corrugated the sand as deep as 28 cm (mean depth: 5.86 +/- 4.72 cm), with the deepest rutting occurring between the foredunes and the drift line. On a volume basis, vehicles disrupted 5.8% (Main Beach) and 9.4% (Flinders Beach) of the available faunal habitat matrix (top 30 cm of the sand) in a single day. Traffic density was higher on the lower shore, but ruts were significantly deeper in the soft sand of the upper shore. Thus, half of all sand displaced by vehicles on Flinders Beach originated from the upper shore, although this section represents only 36% of beach width. Similarly, the narrow (13% of beach width) upper shore on Main Beach contributed 55% of the total volume of sand dislodged by ORVs. Beach traffic overlapped to a large extent with the distribution of the invertebrate infauna, and vehicles routinely disturbed the drift line and the base of the foredunes. This study emphasizes the need to develop multifaceted management strategies for recreational ORV use on beaches that balance ecological requirements with sociocultural and economic demands.