Old-growth forests are natural forests that have developed over a long period of time, without experiencing severe, stand-replacing disturbance a fire, windstorm, or logging. According to UNEP/CBD/SBSTTA definition, an old-growth forest is a primary or a secondary forest which has achieved an age at which structure and species normally associated with old primary forests of that type have sufficiently accumulated to act as a forest ecosystem distinct from any younger age class. In a thematic contribution to the National Biodiversity Strategy, the authors report the following definition of Italian old-growth forests: Forest in which human disturbance is absent or negligible, and in which natural dynamics create a mosaic of all the forest regeneration phases, including the senescing one. Such phase is characterized by large old trees, deadwood (snags logs and coarse woody debris) and a vascular plant species composition that is consistent with the biogeographical context and includes highly specialized taxa related to the small-scale disturbance and the microhabitats resulting from structural heterogeneity. In Sicily, 472 hectare were recognized as old-growth forests mainly distributed in Regional Natural Parks, Reserves, Site of Community Importance (SCI) and, Special Protected Areas (SPA). In particular, 18 forest areas, located over 1000 m of altitude and characterized by high index of woodiness, were surveyed in the provinces of Caltanissetta, Catania, Messina and Palermo. In the frame of a research project granted by the University of Palermo, an investigation was carried out in the “Bosco Pomieri”, an old-growth forest included in the Madonie Park (N.-Sicily). In 2013, a multidisciplinary research team started to analyse vascular plant and the cryptogamic diversity, and also carrying out some plant physiology tests and an environmental monitoring. The “Bosco Pomieri” is a mixed oak wood characterized by the presence of many old trees of Quercus petraea (Matt.) Liebl. subsp. austrothyrrenica Brullo, Guarino & Siracusa and a dense shrub layer with Ilex aquifolium L. In the forest area we also find Fagus sylvatica L., Acer pseudoplatanus L., A.obtusatum W. & K., Ulmus glabra Huds., Sorbus torminalis L., Malus sylvestris (L.) Mill., and, sporadically, Quercus cerris L. and Q. pubescens s.l. Shrubby species, such as Daphne laureola L., Crataegus laciniata Ucria, Ruscus aculeatus L. and, Rhamnus catharticus L., are also present in the investigated area (5, 6). Preliminary results of the investigation carried out in the “Bosco Pomieri” are here reported. At present, 9 benthic algal taxa of algae belonging to the Divisions Cyanophyta, Rhodophyta, Chlorophyta, and Bacillariophyta are currently listed. 74 lichens, mainly epiphytic, belonging to the genera Caloplaca Th. Fr., Lecanora Ach., Physcia (Schreb.) Michx. and Ramalina Ach. Fungi are currently represented by 62 saprotrophic, parasitic and mycorrhizal species.
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