Seasonal Changes in Tissue Water Relations of Three Woody Species of the Quercus‐Carya Forest Type
1982
Parker, William C. | Pallardy, Stephen G. | Hinckley, Thomas M. | Teskey, Robert O.
Tissue water relations of white and northern red oaks and mockernut hickory were studied during the growing season of 1979. In all species, osmotic potentials at full saturation and turgor loss point decreased during the period of leaf maturation; subsequently, osmotic potential responded to soil moisture availability. Estimates of the bulk modulus of elasticity and the relative water content at the turgor loss point revealed that white oak possessed less elastic leaf tissue than did either northern red oak or hickory. The bulk leaf pressure potential associated with the initiation of stomatal closure was lower in white oak and hickory (0.2 MPa) than in northern red oak (0.4 MPa) and remained seasonally constant, while total leaf water potential associated with stomatal closure was lower during periods of drought as osmotic potential decreased. The drought—tolerating behavior of white oak is consistent with its frequent occurrence and success in xeric habitats. Northern red oak and mockernut hickory exhibited responses more typical of drought—avoiding species, which would result in sustained turgor—mediated processes essential for growth and high competitive ability at moderate moisture stresses characteristic of more mesic habitats.
显示更多 [+] 显示较少 [-]