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Báo cáo khoa học: "Water acquisition patterns of two wet tropical canopy tree species of French Guiana as inferred from H218O extraction profile"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Water acquisition patterns of two wet tropical canopy tree species of French Guiana as inferred from H218O extraction profiles. | 717 Ann. For. Sci. 57 2000 717-724 INRA EDP Sciences Original article Water acquisition patterns of two wet tropical canopy tree species of French Guiana as inferred from H218O extraction profiles Damien Bonala Claire Atgerb Têté Séverien Barigaha André Ferhic Jean-Marc Guehld Bruno Ferryb aSilvolab Guyane Écophysiologie Forestiere INRA Kourou BP 709 97387 Kourou Cedex Guyane Frangaise bLaboratoire de Recherches en Sciences Forestieres ENGREF 14 rue Girardet 54042 Nancy Cedex France cCentre de Recherches Géodynamiques Université Paris VI 47 avenue de Corzent 74203 Thonon-les-Bains France dUnité d Écophysiologie Forestiere INRA Nancy 54280 Champenoux France Received 3 January 2000 accepted 9 May 2000 Abstract - We inferred water acquisition patterns of two major tropical rainforest canopy tree species during wet and dry seasons in different soil drainage conditions based on the natural abundance of 18O in soil and xylem water and on descriptions of the vertical extension of root systems. Vertical 18O patterns in the soil were not monotonic and spatially distinct soil layers displayed similar 18O values. Therefore vertical patterns of water extraction could only be interpreted by combining the isotopic data with observed root and soil moisture vertical distributions. On sites with deep vertical drainage DVD Eperua falcata was able to absorb water down to at least -3.0 m depth whereas Dicorynia guianensis depended solely on superficial layers. On sites with superficial lateral drainage SLD the rooting system of both species was less deep but Eperua falcata was still able to extract water around -2.0 m depth. Despite these distinct patterns there was no effect of seasonal soil drought on leaf water status. In terms of adaptation to seasonal soil drought the strategy of Eperua falcata might be advantageous under occasional severe soil moisture stress. H218O rainforest canopy tree water acquisition Eperua falcata Dicorynia guianensis water-use efficiency Résumé - .