Conservation of the Mediterranean coastal pine woodlands: How can management support biodiversity?

Forest management decisions may have unintentional effects on what they were originally not designed for, including effects on woodland species and communities. In protected areas of coastal dune woodlands, some sites are fenced as a part of forestry management. In this study, we hypothesised that different states of disturbance (disturbed vs non-disturbed) created by fencing generate unintentional heterogeneity in species composition (and possibly richness) in plant communities and soil biota. We surveyed vascular plants, oribatid mites and soil properties in fenced and nearby non-fenced places in protected coastal pine woodlands in Italy. The fenced areas were undisturbed for at least 30 years, whereas the non-fenced areas were subjected to thinning and trampling. Effects of fencing on community composition and soil properties were assessed by (distance based) redundancy analysis. Congruence between plant and mite community composition in response to fencing was tested using a series of (partial) Mantel tests. Finally, linear mixed-effects models were used to study species richness. Both plant and mite community composition showed a significant congruent response to fencing. Species richness of plants decreased due to fencing, while that of mites was unaffected. We conclude that the fencing of small areas creates biotic heterogeneity and increases beta diversity in the Mediterranean coastal woodlands. Therefore, we support the use of fencing as a relatively cheap and effective method of conservation management for maintaining the biodiversity of both above- and belowground communities in the coastal pine woodlands of the Mediterranean area.