Essai sur la végétation du Mont Lozère comparée à celle de l'Aigoual

Abstract

Comm!lnication n° 127 d~M!, station intern. de Géobotanlque méditerranéenne et alpine. 1. D'ajJrès WEYD (v. NÈGRE, 1934) deme vieux S111pins existent encore dans la forêt de Gourdouze, versant sud du l\lont Lozère.

Post-grazing Scots pine colonization of mid-elevation heathlands: population structure, impact on vegetation composition and diversity

“…This area was chosen as representative of the forest colonization process on formerly grazed heathlands. The upper plateau is a mosaic of heathlands dominated by Festuca rubra, Calluna vulgaris, Vaccinium myrtillus, Deschampsia flexuosa and Genista purgans [8], and Nardus-dominated grasslands (Nardetea strictae Rivas Goday & Borja Carbonell 61) (see Appendix). These communities (indicated below as 'heathlands') partly result from grazing practices, and naturally evolve towards acidic beech forests [8,32].…”

“…The upper plateau is a mosaic of heathlands dominated by Festuca rubra, Calluna vulgaris, Vaccinium myrtillus, Deschampsia flexuosa and Genista purgans [8], and Nardus-dominated grasslands (Nardetea strictae Rivas Goday & Borja Carbonell 61) (see Appendix). These communities (indicated below as 'heathlands') partly result from grazing practices, and naturally evolve towards acidic beech forests [8,32]. They exhibit low grazing values, but are locally protected because of their spatial regression, and the presence of certain relict alpine species such as Leontodon pyrenaici subsp.…”

“…The database comprised the main biological and auto-ecological traits such as life form [33,45], dispersal mode [33], biogeographic origin [18], grazing value [13], and adaptive strategy according to Grime's CSR-classification [22,23]. Endemic species were listed according to Braun-Blanquet [8] and the personal knowledge of a member of the team. The Ellenberg indicator values [18,33] for light, moisture, nitrogen, acidity, nutrient availability, temperature and continentality were also calculated on the basis of the absence or the presence of species.…”

“…Thorny, scented and/or toxic species (= unpalatable) were set apart and noted CSR-adaptive strategy [22] Competitive (C), stress-tolerant (S), ruderals (R), and intermediate strategies (C-S, S-C, S-R and C-S-R) Phytosociological association [33] Nardetalia-Nardion, Violion caninae, Molinio-Arrhenatheretea, Querceti-robori + Fagetea, indifferent, anthropo-zoogeneous [8]) species such as Nardus stricta were relatively frequent in heathlands. They decreased quite regularly with tree colonization and stand maturation, whereas Cosmopolitan species increased.…”

“…Nardus-dominated grasslands and heathlands on acid, nutrient-depleted and sandy soils occupy the central upper part of Mont-Lozère (150 km 2 ). They are protected according to the "Natura 2000" European regulation owing to their spatial regression and regional rarity, and to the presence of relict alpine species [8]. This mosaic results from traditional extensive grazing, shrub-clearing and burning practices, which have been almost completely abandoned since the 1950's [32].…”