Ecological profiles of wetland plant species in the northern Apennines (N. Italy)

摘要

Eighteen selected species occurring in the wetlands of the northern Apennines were studied by the ecological profile method. By this method, it is possible to identify the ecological factors mostly influencing species distribution within a particular vegetation. Moreover, it is possible to evaluate both ecological amplitude and ecological preferences of species. Ecological profiles were built for three factors (altitude, pH and electrical conductivity) from a data set of 265 phytosociological relevés, used for altitude, and from a set of 92 measures, carried out in selected sites, for idrochemical variables. By numerical classification, based on chord distance and minimum variance, the ecological species groups for each factor were individuated. Subsequently, they were ordered by correspondence analysis for detecting relationships between ecological groups and classes of factors. By applying a goodness-of-fit test to ecological profiles, the species significantly deviating from uniformity were detected. They can be regarded as indicators for the corresponding ecological factor. We found seven indicator species for altitude (Carex nigra, C. rostrata, Juncus filiformis, J. alpino-articulatus, Eriophorum latifolium, E. angustifolium and Warnstorfia exannulata), four indicator species for electrical conductivity (Campylium stellatum, Carex tumidicarpa, Eriophorum latifolium and Juncus alpino-articulatus) and one indicator species for pH (Sphagnum capillifolium). The ecological profiles of the wetland species in the northern Apennines were compared with those reported in literature for the same species from the Alps (namely Dolomites). In this way, a certain degree of ecological shift in several wetland species of the northern Apennines was documented. For altitude, it is possible to explain the shift considering the reduced elevational amplitude of northern Apennine wetlands with respect to those of the Alps. For pH, Sphagnum capillifolium occurs in less acidic habitats than in the Alps, probably due to the absence of ombrotrophic mires, and Viola palustris occurs mostly in neutro- basiphytic habitats. Some hypotheses to explain the ecological behaviour of this last species were proposed.