Can plant species migrate through the European Ecological Network?

Climate change forces plant species to either adapt or migrate to new suitable habitat. On a European scale the plant species will have to migrate through a highly fragmented landscape, where suitable habitat is surrounded with unsuitable agricultural and built-up areas. The European Ecological Network (EEN) is designed to link the natural areas in Europe and make migration through Europe possible. It is assumed that in the near future the Netherlands and North Germany will have the temperature of Southern France. This may force plant species to migrate over 1300 km to stay in the same temperature zone.

We applied the dispersal model DIMO to evaluate the EEN by varying the dispersal capacity, habitat and dispersal vector (wind, animal). The model runs were initiated with fictive dispersal capacities in Southern France and run until the North of Germany and the Netherlands was reached or when dispersal was limited due to lack of connectivity (Fig. 1).

For the combination forest and dispersal by animals, without barriers, the maximum distance is almost reached with a dispersal capacity of 7 km per year as is the occupied area of available habitat (99%, Table 1). With a dispersal capacity of 15 km per year the most Northern part of our research area is reached. All available habitat is occupied with a dispersal capacity of 50 km per year. For heathland in combination with wind dispersal the minimum dispersal capacity needed to reach the North of the research area is 35 km per year. This indicates that the heathlands in Europe are more fragmented than the forest.

The results show that on a European scale both forest and heathlands are highly fragmented, at least for plant species. Even for forest a dispersal capacity of 7 km per year is needed to reach the target area. Of the over 900 Dutch plant species present in DIMO with known dispersal capacity, only 18% of the species fulfil this criterion and should thus in principle be able to migrate from the South of France to the Netherlands and North Germany. If species from the South of France have the same dispersal capacity as in the Netherlands this would imply that the major part of the species should adapt to the new climate circumstances or they may become extinct. Improvement of the connectivity of the forest may be possible by to be developed forest corridors at the major bottlenecks situated just south of the Netherlands. When implemented the dispersal capacity could be downsized to 2 km per year, which will allow 52% of the species to migrate.