Quercus cerris thermophylous woods in Molise: phytososciological characterization and phytogeographical relationships.

phytosociological study of the Carpinion orientalis and Crataego laevigatae-Quercion cerridis thermophilous hilly woodland in Molise is herein presented. Two matrix containing 99 relevés (published and unpublished) collected in Molise and 31 synoptic tables obtained from the consultation of 22 works published on the thermophilic Quercus cerris woods of the Italian peninsula were statistically analysed. The results of the first classification showed 8 clusters grouped in three associations. The first one refers to the Lonicero xylostei-Quercetum cerridis association (subass. typicum, subass. festucetosum exaltatae, var. with Euphorbia amygdaloides, var. with Quercus ilex) distributed in the Mediterranean areas of the region. The second one refers to the Daphno laureolae-Quercetum cerridis association (subass. rosetosum arvense, var. with Brachypodium rupestre, var. with Festuca exaltata) distributed in the central part of the region on sandy-clayey soils with temperate climate. The third association (Echinopo siculi-Quercetum frainetto) finds the north-eastern limit of its distribution in Molise. It occurs in temperate areas and is connected with level ground or gentle slopes with substrates mainly represented by sandy soils, showing a clear edaphic determinism. For more conservative sites the new subassociation maletosum florentinae is proposed. The Lonicero xylostei-Quercetum cerridis and Daphno laureolae-Quercetum cerridis associations are included in the Carpinion orientalis alliance; the Echinopo siculi-Quercetum frainetto association refers to the Crataego laevigatae-Quercion cerridis alliance. Through the results obtained from the elaboration of the synoptic tables, we tried to relate the thermophilic Turkey-oak associations from Molise with the similar ones described for the Italian peninsula. The resulting relationships are complex. First, we confirm the hypothesis that sets Southern Molise as a phytogeographical limit for several woodland associations (e.g. Tilio-Acerion forests). Therefore, and despite its small surface area, Molise represents a focal point for the Quercus cerris forests where the corotypes of SE European, Euroasiatic and European-Caucasian have a significant presence. Moreover, 17 different associations have been used to describe the thermophilous oak woods of the Italian peninsula. Through the centuries, the thermophilic oak forests have been very much altered by human activity. Therefore, they have been floristically simplified. This may be one the reason why several existing associations are redundant despite many Quercus cerris woods are similar.