Canopy water storage capacity and it`s effect on rainfall interception in a Pinus eldarica plantation in a semi-arid climate zone

Forest canopy rainfall interception loss (I) and canopy water storage capacity (S) are important components of the water balance in arid and semi-arid climate zones. The goal of this research was to quantify S and free throughfall (p) in a mature Pinus eldarica Medw. afforestation planted in the Chitgar Forest plantation near Tehran, Iran. Measurements of gross precipitation (GR (n=6)) and throughfall (TF (n=45)) were recorded on an event basis from September 2009 to April 2010. I was calculated as the difference between GR and TF. For the measurement period, GR totaled 164.8 mm and rainfall interception loss (I) was 61.2 mm. In this study S was estimated as 1.7 mm, 1.4 mm and 1.8 mm by methods of Leyton, Gash and Morton, and Pypker- Jackson, respectively. Free throughfall (p) was estimated 0.1422. I was estimated 44% and 91.3% of total GR for rainfall events sufficient to saturate the canopy (GR>1.6 mm) and insufficient to saturate the canopy (GR>1.6 mm), respectively. The results demonstrate that canopy storage capacity represents a considerable portion of intercepted rainfall from GR in P. eldarica plantation regions of the semi-arid climate zone of Iran where soil moisture is a limiting factor on plant growth and productivity