Decision-making in road ecology: developing the framework. Prof. John Bissonette. Part 3

The built infrastructure of the roaded landscape has changed the nature of nature. Landscapes that once provided access to resources for abundant wildlife populations have been changed. In many cases landscape integrity (nutrient cycling, energy flow) and permeability (scaled animal movement) have been compromised and biodiversity impacted. Species that once were able to move across the landscape to find needed resources with little difficulty, now find the built infrastructure as barriers to free movement.

In many areas the most vulnerable species (high trophic level, narrow habitat requirements, and those with large area requirements) have been severely reduced or eliminated. Piecemeal and local solutions have been developed, but larger extent landscape-wide efforts are needed to insure the well being of a countrys biota. This is not a trivial task. Given increasing human populations, higher traffic volumes and speed, as well as a dramatically increasing number of vehicle miles driven each year, the problem for engineers and planners concerned with highway construction has become one not only of providing the transportation services that people demand but at the same time, maintaining the ecosystem services (clean air, water, fertile soil) as well as open space and landscape permeability that insure the wellbeing of both humans and wildlife.

These issues are global. In the U.S., we have addressed the roaded landscape issue with the development of a web-based Decision Guide for engineers and biologists (www.wildlifeandroads.org) funded by the U.S. National Academy of Sciences and Engineering-Transportation Research Board-National Cooperative Highway Research Program. The guide is intended to be used in mitigation decisions involving wildlife crossings. The overarching purpose is to restore landscape permeability while at the same time improving human safety on the roads. The decision guide provides background ecological information on the installation of wildlife crossings, including an assessment of appropriate spacing for structures in hotspot areas of wildlife mortality on the road. In this presentation, I discuss the elements of the Decision Guide, address some technical issues of maintaining a well functioning web site, and end with some take-home lessons for biologists and engineers who will need to work together to construct wildlife friendly crossing structures.

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