Diaspore bank of bryophytes in Mediterranean temporary ponds

Diaspore banks are crucial for the maintenance and resilience of bryophytes species in Mediterranean temporary ponds, but the analyses of bryophyte’s spores remain poorly known. In Europe, Mediterranean temporary ponds are indicated as priority natural habitats under the Habitat Directive 92/43/EEC (1): in those habitats bryophytes are recognized to have an important ecological function. Although little is known about the role and function of bryophyte diaspore banks in Mediterranean temporary ponds, bryophytes are a large and important component in these habitats, contributing to the high species richness and diversity (Cogoni et al., 2016). Several authors have studied the population dynamics of some bryophytes confined to fragmented and temporary habitat (Gumey and Nisbet, 1978; Roughgarden and Iwasa, 1986; Fahrig and Paloheimo, 1988) and, in particular, studies conducted by Herben & Söderström (1992) show that the most important factor that regulates the survival of the species is the ability to form new colonies on fragmented substrates. Our aim is to determine what are the species that show a better fitness for survival and adaptation in Mediterranean temporary ponds, in order to evaluate the conservation status of the studies ponds. The sites selected for this study are located in Southern Sardinia, Italy (Usellus and Giara of Gesturi). Soil samples were sampled in the rainy season; samples were collected to test an ex situ germination of spores. The first results showed the capacity of species to germinate in ex-situ conditions, in particular: Archidium alternifolium (Hedw.), Dicranella humilis R.Ruthe, Epipterygium tozeri (Grev.) Lindb, Brachythecium rivulare Schimp, Riccia canaliculata Hoffm. and Mitt. Bryum sp., Tortula sp., Fossombronia sp. and Tortella sp. It is possible to observe as these bryophytes are the most recurring in the study area, showing a better fitness for survival and adaptation to these environments. Species characterized by shuttle life strategy, such as Riccia, achieve their establishment and survival by the large spores which are present in the diaspore bank. The presence of large numbers of viable spores in deeper soils could serve as “insurance” against local extirpation and it might be a winning strategy in Mediterranean temporary.