Il monitoraggio di Specie/Habitat nei Siti Natura 2000: criteri di prioritizzazione nel contesto regionale

Natura 2000 Network in Umbria Region (Central Italy) currently includes 104 Sites (97 SCI and 7 SPA), with a total area of about 135,000 ha corresponding to 15.9% of the regional territory. Thanks to a process coordinated by the Regional Office, Annex I Habitats have been mapped in each Natura 2000 Site at a detailed scale (1:10.000), by a large group of experts, in order to provide basic tools to develop management plans. On the ground of the last updatings, 41 Habitats from Annex I and 4 species from Annex II and have been detected; more than half of the whole regional Network appears to be covered by Habitats. According to Art. 17 of 92/43/EEC Directive, their conservation status should be monitored each 6 years. Even if Umbria is a relatively small Region (one of the smallest in Italy, about 845,600 ha), it is evident that this task represents an exacting job and calls for a serious planning, based on the use of priority criteria. Do all the Species/Habitats need the same type/recurrence of monitoring? If not, which criteria might be followed to create a priority list? Which aspects count more at the regional scale? A discrimination among priorities for each Species and Habitat becomes absolutely necessary. Aim of the present analysis is to discuss models and indicators which can offer a support for the assessment of the intrinsic value of Species/Habitats in order to prioritize their importance in the actual and potential biodiversity of a territory. Among the possible criteria for evaluating their relevance, these should be considered: presence/number of relevant Species (Annex II, Red Lists...); Habitat's phytocoenotic diversity; Habitat's extent, fragmentation and isolation; local potential diversity, with reference to Natural Potential Vegetation; dynamic processes (need of active management); number of Habitats per ecosystem/mosaic; type and number of specific threats. The information deriving from the regional knowledge (Vegetation Series/NPV, floristic and phytosociological data, land use) may be combined in order to create a priority list including the most changeable/threatened to the most stable Habitat/Species, offering an important tool for monitoring plans. Furthermore, a crossed analysis with the distribution of the Vegetation Series may offer the possibility to point out the uneven distribution of Natura 2000 Sites with respect to the actual and potential coenotical diversity of the territory. Besides a methodological screening, the present contribution provides an overview of some case studies about Annex II species [Ionopsidium savianum (Caruel) Ball ex Arcang., Klasea lycopifolia (Vill.) Á. Löve et D. Löve] and Annex I Habitats (H3150, H3170*, H6210*), which resulted to be among the most susceptible of changes and thus more requiring in monitoring. The regional scale appears to be the most suitable for a realistic evaluation of what, when and where should be done on Habitat and Species.