Branches ou tronc ? Distribution spatiale des lichens Hypotrachyna lividescens, H. revoluta et Parmelinopsis afrorevoluta sur un même phorophyte

Branches or trunk ? Spatial distribution of the lichens Hypotrachyna lividescens, H. revoluta and Parmelinopsis afrorevoluta on the same phorophyte. The spatial distribution of the three corticolous foliose lichens Hypotrachyna lividescens, H. revoluta and Parmelinopsis afrorevoluta was studied in two oceanic localities in southwestern France on the same phorophyte. The boles and crowns of two Prunus spp. were integrally examined ; the substrate diameter, the distance and the specific identity of the nearest macrolichen(s) were written down for each thallus belonging to the three species. H. lividescens is restricted to the branchlets, where it is often associated with Melanelia subaurifera. H. revoluta is the most frequent species ; it occurs on branches, especially those of a small diameter. P. afrorevoluta can be found on trunk as well as branches ; it is frequently associated with Parmotrema chinense. The positions of the three taxons within the contexts of succession and adaptative strategies is briefly discussed.