Contribution au prodrome des végétations de France : les Carpino betuli - Fagetea sylvaticae Jakucs 1967

Here is proposed the declination of the Carpino betu- li-Fagetea sylvaticae Jakucs 1967 class, for the second version of the French vegetation prodrome (PVF2). Divided in 2 sub-classes, it contains 177 associations (165 are fully described in separated sheets), 16 sub-alliances, 17 alliances, 8 sub-orders and 5 orders. This class comes from the splitting of the Querco robo- ris-Fagetea sylvaticae Braun-Blanq. & Vlieger in Vlieger 1937 « superclass », chosen in the first French vegeta- tion prodrome (PVF1, Bardat et al., 2004), as two other ones (Quercetea pubescentis Doing-Kraft ex Scamoni & H. Passarge 1959 and Quercetea robori-petraeae Braun-Blanq. & Tüxen ex Braun-Blanq., Roussine & Nègre 1952).Some other changes has been made compared to the PVF1, also based on an analysis of 16,455 relevés and a critical analysis of choices made in the main vegetation prodromes across western and central Europe. Ecological determinism of each vegetation units has not been forgotten, neither than structural matters and a special importance granted to the trees dominating the canopy in mature stands. Carpino betuli-Fagetea sylvaticae class is split in 2 sub- classes. The first is the Geranio robertiani-Fraxinenea excelsioris and correspond to wet, ravine or scree broadleaf hardwood forests, sharing many nitrogen rich tall herbs with the Galio aparine-Urticetea dioicae H. Passarge ex Kopecky 1969, because of the natural disturbances (flooding, rock avalanches…). The se- cond is the Fagenea sylvaticae, dominated by shade tolerant climax species (mostly beech and white fir). Compare to the PVF1, the main changes deriving from this structure concerns ravine or scree forests and non-alluvial wet oak forests. 2 new orders are proposed in the Geranio robertiani-Fraxinenea excel- sioris, in addition to the former and unchanged order Populetalia albae Braun-Blanq. ex Tchou 1949: the Ulmo-Fraxinetalia excelsioris H. Passarge 1968 corres- pond to non-alluvial wet oak forests, the Aceretalia pseudoplatani Moor 1976 to scree forests. Concerning the Fagenea sylvaticae, the acidophilous order Luzulo luzuloidis-Fagetalia sylvaticae Scamo- ni & H. Passarge 1959 is proposed in addition to the Fagetalia sylvaticae Tüxen in Barner 1931. The last im- portant change is the distinction of the beech-oak- hornbeam alliance Carpino betuli-Fagion sylvaticae R. Boeuf, Renaux & J.-M. Royer in R. Boeuf 2011 from the Carpinion betuli Issler 1931, dry oak-hornbeam vege- tation described in the Quercetea pubescentis Doing- Kraft ex Scamoni & H. Passarge 1959 class. A new sub-order, the Corylo avellanae-Fraxinenalia ex- celsioris Rameau, Mansion & Dumé 1989 subord. nov., is proposed, including secondary pionneer stands, growing on former agricultural or industrial lands, or resulting of heavy overexploitation. Keywords: Querco roboris-Fagetea sylvaticae, Geranio robertiani- Fraxinenea excelsioris, Fagenea sylvaticae, broadleaf, foothill zone, mountain zone, beech, white fi r, linden, marple, oak, hornbeam, ash