SAP FLOW IN CORK OAK TREES AT TWO CONTRASTING SITES IN PORTUGAL

The water use of cork oaks (Quercus suber L.) was studied in two Portuguese oak woodland (“montado”) sites that differed in soil quality and depth and in stand structure.
The thermal dissipation technique was employed on a total number of 26 trees continuously over a period of twelve months.
The results indicate that the sap flux density, J_s, in the outer sapwood (0–2 cm depth) showed no statistically significant trends with stem diameter, and supplementary data for J_s in 2–4 cm sapwood depth seem to back this.
Trees from a less dense stand on poorer shallow soil did not differ in daily values of J_s compared to trees with similar stem diameter from a nearby, denser stand on less poor, less shallow soil.
Sap flow in the outer sapwood (Q) reached highest values > 100 kg d^-1 for a dominant tree with a stem diameter of 50 cm.
Generally, daily and half-hourly maxima of J_s and Q were higher in spring and lower at the peak of the summer drought.
Reductions in J_s or Q in summer compared to spring were similar at the two sites.

VII International Workshop on Sap Flow

M.W.T. Schmidt, D. Schreiber, A. Correia, N. Ribeiro, P. Surový, D. Otieno, J. Tenhunen, J.S. Pereira

Quercus suber, montado, dehesa, competition, tree water use, transpiration

https://doi.org/10.17660/ActaHortic.2009.846.40