The synergistic effect of combining woodlands and green veining for biodiversity

Combining nature reserves with small semi-natural elements (green veining) may improve the persistence of plant and animal species in fragmented landscapes. A better understanding of this synergy is essential to improve species diversity in the European Natura 2000 sites and in green veining elements. To test this hypothesis, we investigated the relationship between the occurrence of 40 forest plant and animal species in 1,000 km grid cells in the Netherlands and the spatial cohesion of the surrounding large woodlands and small woody elements. Two types of synergy were found. First, nine species were more often present if there was more cohesion of large elements; small elements enhanced this effect. Second, 11 other species were more often present when there was more cohesion of small elements; large elements enhanced this effect. Eight species showed both effects, indicating two-way synergy. The remaining 12 species preferred landscapes dominated by either large or small elements, or displayed no positive relationship whatsoever to woody elements. Species showing synergy often had a low dispersal capacity; the type of synergy seemed to be related to their habitat preference. These results imply that species diversity could be improved by integrating different policy instruments used for nature reserves and green veining. Using a zoning principle where green veins surround and connect nature reserves, the different spatial and habitat preferences of species can be secured. In this way a coherent network could become reality.