tailieunhanh - Báo cáo lâm nghiệp: "Water relations of adult Norway spruce (Picea abies (L) Karst) under soil drought in the Vosges mountains: whole-tree hydraulic conductance, xylem embolism and water loss regulation "

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài:"Water relations of adult Norway spruce (Picea abies (L) Karst) under soil drought in the Vosges mountains: whole-tree hydraulic conductance, xylem embolism and water loss regulation. | 113 Ann Sci For 1996 53 113-121 Elsevier INRA Original article Water relations of adult Norway spruce Picea abies L Karst under soil drought in the Vosges mountains whole-tree hydraulic conductance xylem embolism and water loss regulation p Lu 1 p Biron 2 A Granier1 H Cochard 1 Laboratoire d ecophysiologie et bioclimatologie INRA 54280 Champenoux 2 CEREG ULP 3 rue de I Argonne 67000 Strasbourg cedex France Received 27 February 1995 accepted 22 August 1995 Summary Drought-induced changes in whole-tree hydraulic conductances gL were monitored throughout a growing season in a 30-year-old stand of Picea abies. gL was derived from concurrent measurements of leaf water potentials and sap flux densities through the trunk. Soil water deficits clearly reduced gL the reduction being most likely located in the soil-root compartment of the soil-plant sap pathway. The decreases in gL did not result in large decreases in midday leaf water potentials because midday sap flux densities were reduced proportionally to gL. Ne therefore hypothesized that maximum sap flux densities in Picea abies are adjusted under dry conditions according to changes in whole-tree hydraulic conductances with effect of maintaining midday water potentials above the point of xylem dysfunction caused by water stress-induced cavitations. hydraulic conductance I cavitation I stomatai conductance drought I sap flux water potential Picea abies Resume Relations hydriques Chez répicéa commun Picea abies L Karst soumis à une sécheresse édaphique dans les Vosges conductance hydraulique totale embolie du xylème et regulation des pertes en eau. Les variations de conductances hydrauliques totales induites par une Correspondence and reprints. Abbreviations F water flow dF. sap flux density dFmidday and predawn dF at midday and predawn respectively GL whole-tree apparent hydraulic conductance gL sapwood-area-specific GL gs. stomatai conductance for H2O K hydraulic conductance of a xylem segment Kịnit initial K Kmax K at