Over The Horizon

Roads Must Roll?

The ecological impact of new roading and how such impacts can be mitigated is the subject of common research at Lincoln University and the University of Southampton, England.

Ian Spellerberg, head of Lincoln's newly established Department of Resource Management, has been contracted by the Department of Conservation to undertake research on the ecological effects of new roads in protected areas. Previously Spellerberg was director of the Centre for Environmental Sciences at the University of Southampton, where he and colleague Martin Gaywood researched the role of roads as "wildlife corridors".

The objectives of the New Zealand research are to identify and assess the ecological impacts (during construction and use) of new roads on the natural environment, habitats and species of protected areas; and to identify ways of mitigating such impacts, such as by ecological buffer zones. These would be constructed as natural vegetation communities, and possibly changes in landform, based on research on the extent to which perturbations from roads enter the natural communities and alter those communities. Spellerberg supervised this area of research while in England.

In the UK, the edges of roads and motorways have long been thought to act as wildlife corridors, providing habitats and movement routes for a range of local fauna. The research undertaken by Spellerberg and Gaywood showed that there are comparatively few studies which support the idea that such corridors facilitate dispersion between populations. They did draw attention to the environmental and amenity benefits of what were termed "linear landscape features" which may act as corridors.

Linear landscape features include natural features such as river banks and forest edges, and also artificial features such as railway lines, powerline swathes, wind breaks and hedgerows. Some of these may help to facilitate dispersion and could therefore be called wildlife corridors. Environmental benefits of linear landscape features include moderated microclimates, avenues of trees in cities helping to take up pollutants, shielding houses from car lights. Along some linear landscape features, such as river banks, are developed walkways or "greenways".

Spellerberg and research assistant Toni Morrison are undertaking a literature search, including electronic media such as the World Wide Web, for information on the ecological effects of roads on natural areas, hoping to build up objective, quantifiable material on the issue.

"It is timely that such research was undertaken. The costs and benefits of new roads should include an appraisal of the ecological effects," says Spellerberg. "This is particularly so when the process of fragmentation of habitats is one of the greatest, if not the greatest, threats to wildlife in New Zealand and overseas."