34.322 - Middle European Bromus erectus semidry grasslands (Classification Paléarctique (PHYSIS 2001))

34.322 - Middle European Bromus erectus semidry grasslands

34.321 - Northwestern semidry calcareous grasslands

34.323 - Middle European Brachypodium semidry grasslands

Classification des habitats du Paléarctique (2001)

Description

Mesophile and mesoxerophile calcareous grasslands of the sub-Atlantic domaine in the Low Countries, Germany, the Czech Republic, Switzerland, northern, central and western France and northwestern Spain. They are faunistically and floristically rich and the highly discontinuous nature of their distribution gives rise to a considerable geographical variation in the composition of plant and animal communities, marked by the occurrence of numerous species of local or disjunct occurrence in addition to the basic cortŠge common to most of them. Besides this geographical variation, the nature of these grasslands also depends, to a great extent, on hydric regime, substrate characteristics and agropastoral treatment, notably on whether they are mowed or grazed and how intensively. In particular, the relative abundance of the main constituent grass species, Bromus erectus, Brachypodium pinnatum s. l., Sesleria albicans and Koeleria pyramidata, varies both geographically with climatic conditions and locally with topography and agropastoral regime. Thus, although separate geographical entities may differ in that relative abundance, similarly differing facies may also coexist locally, producing sharply distinct habitats. To accomodate for these concurrent axes of variation, formations dominated by Brachypodium or by Sesleria, as well as all semidamp formations, are removed from this division and placed in units 34.323, 34.324 and 34.325. Geographical subdivisions, most apt at identifying distinctive plant and animal communities, may be used in the four sections by addition of a fourth decimal digit common to all of them. The regions encompassed by the geographical subdivisions corresponding to each value of this fourth digit are in all cases described under this section although in some of them, or in parts of some of them, there may be no grasslands belonging to unit 34.322, but only grasslands belonging to units 34.323, 34.324 or 34.325; these cases have, as much as possible, been identified under each of the subdivisions below.

Bibliographie

Devillers P., Devillers-Terschuren J. & Vander Linden C., 2001. PHYSIS Palaearctic Habitat Classification Database. Updated to 10 December 2001. Institut Royal des Sciences Naturelles, Bruxelles. (Source)

Lebrun & al., 1949; Tüxen and Oberdorfer, 1958; Ellenberg, 1963, 1988; Braun-Blanquet, 1976; Petit and Ramaut, 1970, 1985; Guinochet and Vilmorin, 1973; Lambinon, 1974; Schumacher, 1977; Rivas-Martinez, 1977a; Gruber, 1978; Bournérias, 1979, 1984; Sipkes, 1980; Wolkinger and Plank, 1981; Ozenda, 1981; Noirfalise and Dethioux, 1982; Duvigneaud, 1982a, 1982b, 1983a, 1983b, 1985; Moravec & al., 1983; Rivas-Martinez & al., 1984b; Polunin and Walters, 1985; Dupias, 1985; Bobbink and Willems, 1987; Loidi Arregui, 1987; Diaz Gonzalez and Fernandez Prieto, 1987; Vigo and Ninot, 1987; Chas, 1989; Zimmermann & al., 1989; Oberdorfer, 1990, 1993a; Mucina and Kolbek, 1993a.