TAILIEUCHUNG - Báo cáo khoa học: "condary succession of Alnus viridis (Chaix) DC. in Vanoise National Park, France: coexistence of sexual and vegetative strategies"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: econdary succession of Alnus viridis (Chaix) DC. in Vanoise National Park, France: coexistence of sexual and vegetative strategies. | Ann. For. Sci. 59 2002 419-428 INRA EDP Sciences 2002 DOI forest 2002016 419 Original article Secondary succession of Alnus viridis Chaix DC. in Vanoise National Park France coexistence of sexual and vegetative strategies Fabien Anthelme Lionel Cornillon and Jean-Jacques Brun Laboratoire Écologie Spatiale et Fonctionnelle Unité de Recherche Écosystèmes et Paysages Montagnards CEMAGREF Grenoble 2 rue de la papeterie BP 76 38402 St-Martin-d Hères Cedex France Received 23 April 2001 accepted 29 August 2001 Abstract - In the western Alps Alnus viridis expansion on subalpine grasslands brings major modifications in the functioning of ecological systems. The aim of this study was to assess which reproduction strategies were responsible for colonization and persistence of the shrub. Indices of vegetative and sexual reproduction were assessed in four 100 m2 sites distinguished by the date of A. viridis settlement to determine the prevalent strategy as a function of age of the A. viridis stand. Results indicated that sexual allocation to reproduction was effective in all situations whereas layering was absent in the site displaying the most recent A. viridis settlement. The number of cones per individual declined significantly from strictly sexual-related individuals to individuals displaying both reproduction strategies. Mann-Whitney test U 132 P . On these grounds we argue that A. viridis colonization process on secondary succession is supplied exclusively by sexual reproduction. In contrast temporal persistence of dense stands is thought to require layering which is also hypothesized to maintain a mechanism of inhibition towards arboreal coniferous species of late successional stages. land disuse reproduction strategy subalpine succession Résumé - Succession secondaire de Alnus viridis Chaix DC. dans le parc national de la Vanoise France coexistence de strategies sexuelle et vegetative. Dans les Alpes occidentales l expansion d Alnus viridis surpelouses .

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