Odonata species richness in the Castelporziano presidential estate, present and past

Abstract

The Castelporziano estate, a former game reserve along the Tyrrhenian coast near Rome, is a conserved patch of pristine woodland, in which several species of the Odonates breed in numerous small ponds and a few rivulets. The odonate species of Castelporziano have been recorded since the 1930s, with an in-depth survey carried out in 1997–1998. The present, additional survey on the odonate species of Castelporziano aims at contributing to long-term ecological research, by assessing variations in odonate fauna up to the present, and linking them to environmental changes. The presence of adult Odonata species was assessed in the field by two observers at 20 water bodies (ponds and other sites) from mid-March to early November 2012. The presence of shade, riparian and submerged vegetation, fish and the number of drying-up events during the past decade were also recorded. Results showed a small reduction in the number of odonate species for the entire estate, with several qualitative changes in comparison with previous data. On the contrary, a site-specific analysis of changes from 1997–1998 to 2012 revealed a significant considerable reduction in the average number of species. This was linked to a decrease in riparian and submerged vegetation. Drying-up events did not appear to be a crucial factor, and fish and shade were essentially unchanged. In conclusion, the Castelporziano water environment seems to have deteriorated, probably as a consequence of the trampling by wild ungulates in woodland ponds.