Nuove segnalazioni di Buxbaumia viridis (Bryopsida, Buxbaumiaceae) in Alto Adige

Buxbaumia viridis is a rare species of moss listed in the Annex II of the Habitat Directive and in many other national Red List in Europe. It is an epixylic species preferring dead-wood in advanced stage of decay in moist and cool woods. The distribution of Buxbaumia viridis in South Tyrol is almost unknown, as it is based on only three records. Aims of this study were: (i) to update the species distribution in South Tyrol; (ii) to examine the ecological characteristics of the species; (iii) to assess if the species could be considered a useful indicator of forest integrity correlating its occurrence with the deadwood amount. We ascertained the presence of the species in 14 sites, including the three known records. The measure of the most significant environmental variables, allowed to delineate the ecological niche of the species. In South Tyrol the species inhabits the coniferous forests (mostly spruce forests). Its presence is determined by rainfall, aspect, canopy cover and the amount of necromass. In particular, the probability to detect the species in forests with less than 10 m³/ha of necromass, was very low (about 5 %); instead, if the amount of deadwood increases for example to 30 m3/ha, the probability raised to 60 %. This result confirmed that Buxbaumia viridis could be used as indicator of a silvicultural model which aims to the functionality of the forest ecosystem.