At a glance
- The data on undissected low-traffic areas are used to describe the fragmentation of the landscape by transport routes.
- In 2010 undissected low-traffic areas accounted for 23.2 % of Germany’s total land area.
- The target of the Federal Government is to retain a proportion of 25.4 %.
Traffic adversely affects biodiversity by fragmenting habitats and creating noise and air pollution. Humans are affected by the loss of recreational areas. The indicator is based on a threshold area of 100 square kilometres (km²), a size originally defined as a recreational space that allows walkers to go on day excursions largely undisturbed by intrusive sights or sounds.
Low-traffic areas are not necessarily near-natural. In Mecklenburg-Western Pomerania and Brandenburg, for instance, low-traffic areas make up more than 50 % of the total land area. This is largely because these Federal States are sparsely populated and have a lower density of transportation networks and less traffic, especially on regional and local roads. Furthermore, these regions are mainly characterised by intensive agriculture.
Assessing the development
In 2010 undissected low-traffic areas with a minimum size of 100 km² accounted for 23.2 % of the total German land area. In 2000 this figure was still 26.5 %. However, the basis for calculation (traffic density counts) was incomplete in 2000 and 2005. Models were therefore used to calculate traffic loads across the entire road network for the year 2010.
In the National Strategy on Biological Diversity, the Federal Government has set itself the target of keeping landscape fragmentation at least at a constant level (BMU 2007). The level of fragmentation in 2005 has been chosen as the target (25.4 %). However, the indicator value for 2010 is not comparable with those for 2000 and 2005 since in these years the data was incomplete. Closer analysis shows that the indicator value is significantly influenced by traffic loads on the subsidiary road network, i.e. the volume of traffic outside the main transport routes. Thus, the indicator is subject to certain fluctuations, depending on the chosen calculation method. This point must be considered when assessing the target attainment.
The indicator is calculated by determining the proportion of Germany's total land area which is not dissected by transport routes. Dissecting transport routes are defined as roads (motorways, national, regional and local roads) with a traffic density of 1000 vehicles per day or above, at least double-track or electrified single-track railway lines and canals with the status of ‘federal waterway’ (Category IV or above). These areas can be identified using geo-information systems. Modelling and traffic counts (to calibrate the model) are needed to fully determine road traffic densities. The modelling approach for 2010 is described in Bosch & Partner et al. (2013).
Bosch & Partner; University of Kassel; TCI Röhling (2013): Ökologische Risikoeinschätzung auf Bundesebene (final report to the F+E-project 3510 82 3100 on behalf of the Federal Agency for Nature Conservation (BfN); unpublished, can be requested at BfN, in German only).