Access and impact: The spatial effects of off-road vehicles on a saltmarsh wetland in Canterbury, New Zealand : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Landscape Architecture at Lincoln University

Abstract

Saltmarsh wetlands are highly productive environments that provide a wide range of ecosystem services, yet many of them have been lost globally and continue to be degraded. Significant impacts can occur when wetlands are used by off-road vehicles. However, little is known about the extent or significance of their impacts on saltmarsh wetlands, and how to mitigate them through planning, design and management. Using a saltmarsh wetland at Greenpark Sands Conservation Area, along the shore of Te Waihora/Lake Ellesmere, as a case study, this research uses GIS spatial analysis to measure the areal extent and intensity of off-road vehicle damage. The wetland is co-managed by Te Rūnanga o Ngāi Tahu and the Department of Conservation, according to a management plan which seeks to protect mahinga kai, restore and protect indigenous wetland biodiversity and improve the mauri of the lake. Results demonstrated that the total impact of off-road vehicles on the saltmarsh wetland was substantial, being both extensive and intensive. Damage measured in transects stretching from the park’s inland edge to the water’s edge showed that the entire park width had been damaged. Of the 7403 quadrats sampled, impacts were present in 66%, of the samples. Proximity to access increased the intensity of impacts, with an average 19% of off-road vehicle track cover in transects adjacent to roads; compared with 8% cover of damage in transects not adjacent to access gates. With an average vehicle impact cover of 28.3%, glasswort (Sarcocornia quinqueflora)-grass herbfields had the highest concentration of vehicle track cover of any vegetation community, demonstrating a low resistance to off-road vehicle use. Across the park were pockets of very high (50-75%) and extreme (75-100%) cover of off-road vehicle tracks, indicating a high frequency of vehicle use in those locations. The results of this study strongly suggest that the objectives of Te Waihora’s Joint Management Plan are not being met under the current management strategy of Greenpark Sands Conservation Area and that actions must be taken to prevent further off-road vehicle use impacts. Recommended planning, design and management strategies include: limiting the area of ORV use to specified zones with well-defined and hardened routes, protecting areas of ecological importance through permanent or seasonal closure, and altering behaviour of use through site design that both filters the type of use and enhances visitor’s perceptions of the site.