FO5 Forest roads

>> Background information

Development

At present, the total length of the Finnish forest road network is more than 130 000 kilometres. This equals almost 30% of the country's complete road network of 450 000 kilometres. In 2011 altogether 652 kilometres of new forest roads were constructed, which is one of lowest figures since the 1950s. The building of new forest roads peaked at the turn of the 1970s and 80s when more than 4 000 kilometres of roads were built annually.

In many locations the forest road network has reached the optimal density defined on the basis on economic criteria. According to the Act on the Financing of Sustainable Forestry, the maximum density of forests roads is 1.5 km/km2 on productive forest land.

In practice, the optimal distance to nearest forest road has been most commonly defined as either 200 or 400 metres. In a study covering five municipalities in central Finland 10% of forest land was found to lie further than 200 metres and 1% further than 400 metres away from the nearest road in the early 2000s.

In recent years, focus has been shifted from building new roads into improving existing ones. In 2011 more than 3 800 kilometres of forest roads were subject to basic improvement measures.

Impact on biodiversity

Together with clear fellings, the dense forest road network is one of the main factors causing forest fragmentation. Forest roads divide continuous forest areas into smaller patches and increase the area and proportion of patch edges. The fragmenting effect of forest roads has been evaluated as even stronger than that of loggings. Whereas clear felled areas regain their forest cover in time, roads represent more permanent open elements in a forest landscape.

Although the forest road network does take up a considerable land area - the present 130 000 km covers some xxx of forestry land - the most important impact of forests roads on biodiversity comes rather through edge effects than direct habitat loss. Species that benefit from the shading, shelter or micro-climate provided by interior forest areas do not thrive in the more exposed patch edges. Some species may entirely shy away from edge habitats while the reproduction success others may may be inferior there. Some species may also fall prey more easily in edge habitats.

The movement of species may be restricted by the road clearings although clear felled areas are much stronger movement barriers in this respect. The average width of a forest road clearing is xx metres.

For some species forest roads provide new opportunities in the form of passageways into forest interiors and new areas. Species that have most likely benefited from this include several mammalian predator species, such as the Grey Wolf and Raccoon Dog. Forest road open up passageways also for invasive species of which the last-mentioned is a good example.

As a result of the forest road network, effective forestry can now be exercised in all parts of the country. According to studies, the probability of fellings appears to increase at least at the distance of 200 to 300 metres from a new forest road. This is quite expected since better access to loggin areas has normally been the primary reason for the construction new forest roads.