Diversità e conservazione degli Odonati nella Tenuta Presidenziale di Castelporziano: ruolo degli abbeveratoi artificiali

Artificial habitats are useful study systems for testing ecological processes due to natural seriality (i.e., they shared a same physical structure) and the relatively low number of environmental parameters compared to natural habitats. In the Presidential Estate of Castelporziano, there are several drinking troughs dispersed in a system of natural ephemeral pools and ponds. This work used Odonata as model organism to assess species composition and diversity in these artificial aquatic habitats and to compare Odonata fauna between drinking troughs and natural wetlands. Twenty troughs were sampled by dip-netting, collecting Odonata larvae and identifying the species. The diversity of species present in the troughs was characterized and compared with data from a previous study conducted in the natural pools of the Estate. Nearly half (40%) of the species pool recorded from the natural wetlands was also found in the drinking troughs. Larval species richness estimated in troughs was affected by the percentage of submerged vegetation and the isolation (linear distance between the troughs and the nearest natural waterbody) with positive and negative effects, respectively. In addition, the troughs and the ponds were compared by analyzing the “species richness / area of waterbody” relationship: when the area is considered, no difference in the diversity of species between ponds and drinking troughs was found. Overall, our findings underlined how dragonflies perceive and use drinking troughs as a surrogate of natural habitats. This demonstrated that these artificial habitats extended the total area suitable for colonization by small aquatic fauna in the study area and guaranteed the availability of wetlands even during the summer when most natural lentic environments dries up and emphasized the importance of studying and managing drinking troughs within a conservation framework of aquatic organisms.