Stemflow generations in natural and pure stands of Chestnut leaved oak (Quercus castaneifolia C.A.M) and Oriental beech (Fagus orientalis Lipsky) within the summer

Measurements of stemflow (SF) were conducted during the 2009 summer season in pure and natural oriental beech (Fagus orientalis Lipsky) and oak (Quercus castaneifolia C.A.M) forests located in the Kheyrud Forest Research Station of Tehran University. Measurements were made inside two plots of beech and oak forests with areas of 0.56, 0.12 ha, respectively. SF was collected from six beech and oak trees with different diameters by the spiral-type SF collection collars installed at diameter at breast height. Gross rainfall (GR) was collected by means of three manual collectors placed in a neighboring open area from the study plots. All the measurements were performed on a rainfall event basis. During the study period, 10 events were recorded with cumulative GR of 257 mm. The cumulative SF depths for beech forest was 8.1 mm, whilst for oak forest was 0.7 mm. At the event scale, the averages intercepted rainfall by the stemflow in beech and oak forests, i.e. SF/GR, were 2.6%, 0.2%, respectively. A strong positive correlation was observed between [(SF/GR)/GR] (R2= 0.93) in the beech forest, while a weak positive correlation was observed in the oak forest(R2= 0.43). Averages bark roughness indices calculated by the number of bark furrows and furrows depths were measured 2.10 and 0.50 for oak and beech trees, respectively. Although the study indicated that GR allocated to SF is not a remarkable amount in both oak and beech forests, the SF volume in the beech trees is higher than that of oak which was found to be highly correlated with higher bark water storage capacity as well as higher bark roughness of the oak trees