The measurement and modelling of the variation of stemflow in a laurel forest in Tenerife, Canary Islands

The stemflow of 30 sample trees belonging to six different species was quan tified in the laurel forest of Agua Garcia, Tenerife, Canary Islands, durin g a complete year. Different methods described in the literature, for scali ng up the stemflow values from tree level to stand level were applied. The best for this type of forest is based on the application of annual regressi ons between basal area and stemflow in each species, giving a total annual stand stemflow of 42.861 m(-2). This represents 6.85% of annual gross preci pitation. This is not a very high value but important to be taken into acco unt in the determination of the water balance of the forest. An antecedent precipitation of 2 mm was necessary for the initiation of the stand stemflo w. Stemflow attained 10% of gross precipitation during big rain events, bei ng positively correlated with the mean hourly rain intensity. Differences among trees and species were also studied resulting that trees with the biggest crown area, not dominated by their neighbours, and with th e smoothest bark collected the largest volumes of stemflow in the stand. Ba rk roughness, divergence angle of the branches with respect to the trunk an d also the size of the leaves, were responsible for the differences between species. As a consequence of the stemflow the rain can be concentrated up to 12.8 ti mes in the infiltration areas of the trees which could produce better soil conditions for tree growth. The results obtained in the Agua Garcia laurel forest stand are the first stemflow data obtained for the Canarian laurel f orest and they are in the range found in other types of forests. (C) 1999 E lsevier Science B.V. ALI rights reserved.