Testing the predictivity of ecological indicator values. A comparison of real and 'virtual' relevés of lichen vegetation

A complex database on the lichens of Italy was used to combine ecological indicator values assigned to each species (pH, eutrophication, light and aridity), in such a way as to simulate 'virtual habitats' from a beech forest of northern Italy. For each habitat, a list of species was obtained ('virtual releve'). A matrix of real and virtual releves was submitted to classification and ordination, obtaining six main community-types, all of which include both real and virtual releves. Two ordinations of species were carried out, one on the matrix of real releves, the other on that of virtual releves: their comparison shows that the consistency and the resolving power of the indicator values was high, but it also permits to detect and correct some errors. The results indicate a high predictivity of the indicator values for constructing ecological scenarios.