Plant community, ecology and functional strategy of Linaria tonzigii Lona, a steno-endemic species of the Italian pre-Alps

Linaria tonzigii is a rare steno-endemic species of Community interest that grows on some limestone screes in the Orobie Bergamasche Regional Park (Italian Alps) (Fig. 1). Currently, its presence is certain in just a few sites of the Orobic pre-Alps. Many of these sites were refuge areas during the glaciations of the Quaternary Age: Mt. Arera/Mt. Corna Quadra group (locus classicus), Mt. Menna, Mt. Secco, Mt. Ferrante/Mt. Presolana group and Mt. Cavallo/Mt. Pegherolo group. According to the IUCN Red List of threatened species, Linaria tonzigii belongs to the category ‘Endangered D’, and it is therefore subject to strict protection under law LR10/2008 in Lombardy. Information on its ecology (and synecology), and on its Grime's CSR functional strategy are scarce. This study, other than analyzing the floristic composition and ecology of the communities hosting Linaria tonzigii by means of traditional methods (ecological indices), also evaluated its Grime's CSR strategy using the latest methods and tools. Analysis of 24 phytosociological relevés conducted in five different areas revealed that this species is part of a single plant community (Linaria tonzigii-Hornungia alpina community), consisting of basophile and xerophile species, mostly typical of limestone screes. The analysis of the CSR strategy revealed that the main strategy of Linaria tonzigii is R/CSR (Fig. 2), although the species adopts slightly different strategies in different sampling areas. The analysis of plant height showed that the isolated population at the northern limit of the distribution range has significantly taller, and less stress-tolerant individuals, than those in other areas, suggesting that this population may be a different ecotype (1). This study aims at stimulating researchers to study poorly known endemic species, in order to preserve and valorize the biodiversity of protected areas, and hence that of the planet.