Effects of Robinia pseudoacacia in Natura 2000 sites in Italy: a comparison with Castanea sativa woods

Robinia pseudoacacia is the most commonly spread and well-known alien species forming forests in Europe. Many of these forests are found within protected areas (e.g. Natura 2000 sites). However, little is known of the specific impacts that this species can have on the structure and functions of protected natural and semi-natural habitats. In this study we report results from an investigation of paired plots dominated by black locust and chestnut within the Natura 2000 network in the Veneto region (north-eastern Italy). Paired plots have a minimum distance of 1 km and are a commonly applied sampling method for studying effects of invasive species. We surveyed and analysed vascular plant species composition and forest structure. Management was also recorded by differentiating between coppiced and abandoned stands. Results are discussed with reference to the possible effects on biodiversity and structural and functional changes as those derived from variations in snags and logs quantity. These outcomes can help to indicate possible guidelines for the application of prevention and management actions to contrast the threat posed by invasive alien tree species.