tailieunhanh - Báo cáo lâm nghiệp:"Post-grazing Scots pine colonization of mid-elevation heathlands: population structure, impact on vegetation composition and diversity"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Post-grazing Scots pine colonization of mid-elevation heathlands: population structure, impact on vegetation composition and diversity" | Ann. For. Sci. 60 2003 711-724 INRA EDP Sciences 2004 DOI forest 2003065 711 Original article Post-grazing Scots pine colonization of mid-elevation heathlands population structure impact on vegetation composition and diversity Thomas CuRTa Bernard PREVOSTOa Mario KLESCZEWSKIb Jacques LEPARTb a Cemagref Applied Ecology of Woodlands 24 av. des Landais BP 50075 63172 Aubière Cedex France b CNRS Centre d Ecologie Fonctionnelle et Evolutive 1919 route de Mende 34293 Montpellier Cedex 5 France Received 24 June 2002 accepted 10 February 2003 Abstract - Scots pine Pinus sylvestris L. pioneer woodlands have established spontaneously on former grasslands and heathlands on Mont-Lozère Cévennes National Park France since their abandonment in the 1950 s. Subsequently late-successional beech Fagus sylvatica L. has progressively invaded the ageing pine stands. We studied 44 plots according to a gradient of forest colonization and maturation from heathlands to mature beech stands. The objective was to assess the impact of forest colonization on the vegetation composition and richness of legally-protected grasslands and heathlands. Dendrometric characteristics and demography were assessed on each 20 X 20 m plot. An extensive ground vegetation analysis was carried out focusing on plant functional traits that may be sensitive to canopy closure. Results indicated the persistence of most heathland species under pure and young Scots pine stands but quite high species turnover. Xerothermic and strictly shade-intolerant species rapidly disappeared whereas thermophilic forest species were apparent. In submature and mature pine stands the establishment of a beech understorey entailed considerable species turnover and prevent pine regeneration. In pure beech stands ruderal and stress-tolerators were replaced by shade-tolerant and competitive species. Ellenberg s scores for light nutrients and water confirmed the changes in vegetation composition and plant life traits whereas the .