Plant species over-occupancy indicates river valleys are natural corridors for migration

Background/Question/Methods

River valleys are considered as natural corridors for plant species migration, however, there is a lack of studies confirming higher colonisation rate of plant species there. We compare plant species richness between ancient and recent forests located in the river valley, with those located in the surrounding landscape. We assume that closer to a river, higher plant species richness will be associated with recent forests thus indicating a higher colonisation rate. The study area includes part of the Elbe River Valley and its surrounding landscape in the Czech Republic. We sampled an equal number of recent and ancient forests lying at different distances from the river. We used generalised linear models to test the effect of distance from the river in dependence upon forest continuity (recent/ancient forest) on two plant species richness categories, i.e. richness of forest species and overall species richness.

Results/Conclusions

In the surrounding landscape, higher richness of forest species was associated with ancient forests, whereas overall species richness was comparable. In the river valley, richness of forest species as well as overall species richness was higher in the recent forests. Recent forests in the river valley were more saturated by plant species than those in the surrounding landscape, indicating that in the river valley the colonisation rate of plant species is actually higher. These results confirm the importance of river valleys as natural corridors for plant species migration.