Throughfall, stemflow and canopy interception loss by oriental beech trees (Fagus orientalis Lipsky) in North Forests of Iran

Water cycle plays an important role in the interaction between soil, vegetation and environment. It is one of the main ecological phenomena in natural biocenoses particularly in forest ecosystems. Throughfall (TF), stemflow (SF) and canopy interception loss (CIL), account for a large portion of the water cycle in them. In the present study throughfall, stemflow and canopy interception loss by oriental beech trees were investigated in North Forests of Iran for one year from Oct. 2009. Gross rainfall (GR) was measured by four rain gauges located in an open area approximately 150 m from the study plot, TF by sixty TF manual gauges randomly placed beneath the beech canopies and SF by SF collectors (diameter 3 cm) from 20 cylindrical beech trees at different diameter classes with symmetrical canopies. CIL height mean was calculated from the difference between gross precipitation height mean and sum of SF height mean and TF height mean. By application of regression and characteristics of oriental beech trees the most appropriate mode was designed to predict throughfall, stemflow and canopy interception loss in the study plot. The result indicated that out of 1497 mm of annual precipitation the share of stemflow, throughfall and interception loss by oriental beech trees are 1.2, 47.5 and 51.3% respectively. By the increase of gross precipitation height the share of stemflow, throughfall and interception went up. The analysis of the Pearson coefficiency showed that there was significant correlation between these parameters at 99% level of probability. It has been found that as tree diameter class increases SF height mean declines and CIL height mean increases.