Ontsnippering van natuurgebieden: effecten op natuur, mobiliteit, bereikbaarheid, verkeersveiligheid en geluid. Achtergronddocument bij de Nationale Natuurverkenning 2.

Road infrastructure has important impacts on the quality and quantity of animal habitats. Animals are killed by road traffic and roads "fragment" habitats dividing wildlife populations into smaller, more isolated units. This may threaten wildlife species that have to cross roads to meet their biological needs. This report analysed the impacts of wildlife habitat defragmentation due to provincial and municipal roads (by restricting them to local traffic only) in nature areas in the Netherlands. The study analysed both impacts on wildlife (habitat quality, noise levels in nature areas) and humans (passenger mobility, accessibility impacts, noise levels in residential areas, road safety). The study concludes that habitat defragmentation has important benefits for the quality of animal habitats, traffic safety and noise levels in natural and residential areas at the local level, but important negative impacts on accessibility: congestion levels and average travel times increase. A conclusion on the balance of impacts, expressed in monetary terms, can not yet be given. The uncertainty in impacts and their monetary valuation for the impacts on humans is very large, and the impacts on wildlife are difficult to express in monetary terms. Furthermore, it can not yet be concluded if large scale habitat defragmentation by restricting road traffic on local roads is desirable. More research is necessary on alternative measures for habitat defragmentation, relevant impacts, and their costs and benefits