Root and shoot hydraulic conductance of seven Quercus species

The root (K R ) and shoot (K S ) hydraulic conductances of seven different Quercus species, as well as the leaf blade hydraulic resistance (R LL ), were measured in potted plants with the aim of understanding whether a relationship exists between the hydraulic architecture and the general ecological behaviour of different species of this genus. The K R values were scaled by dividing by root surface area (K RR ) and by leaf surface area (K RL ) and the K S values were scaled by dividing by leaf surface area (K SL ). The likely drought-adapted species (Quercus suber, Q. pubescens, Q. petraea) showed lower K RL and K RR , lower K SL and higher R LL with respect to the known water-demanding species (Q. alba, Q. cerris, Q. robur, Q. rubra). The possible physiological and ecologi- cal significance of such differences are discussed. ( © Inra/Elsevier, Paris.) root hydraulic conductance / shoot hydraulic conductance / leaf blade resistance / Quercus / high pressure flow meter Rsum -Les conductivits hydrauliques de la racine et de la tige de sept espces de Quercus. Les conductivits hydrauliques de la racine (K R ) et de la tige (K S ) et la rsistance hydraulique des feuilles (R LL ) des sept espces de Quercus ont t mesures avec pour objectif la comprhension de la relation qui existe entre l'cologie de l'espce et son architecture hydraulique. Les valeurs des K R ont t divises par les surfaces des feuilles (K RL ) et des racines (K RR ), celles des K S par les surfaces des feuilles (K SL ). Les K RR , K RL et K SL des espces adaptes aux environnements arides (Q. suber, Q. pubescens, Q. petraea) sont infrieures et leurs R LL suprieures par rapport aux valeurs de celles adaptes aux environnements humides (Q. alba, Q. cerris, Q. robur, Q. rubra). Cet arti- cle se propose d'illustere ces diffrentces au plan physiologique et cologique. conductivit hydraulique de la racine / conductivit hydraulique de la tige / Quercus / HPFM