Rainfall Interception by a Fraxinus rotundifolia Stand in a Semi Arid Climate Zone of Iran

Research on the forest hydrology will help our understanding in the functions of forest ecosystems. Forest canopy is the first interface factor when gross rainfall (GR) goes into forest, and directly influences the process of water cycle. No research has been reported, to our knowledge, concerning the stand-based measurement of rainfall interception (I) for Fraxinus rotundifolia plantations in Iran. The aim of this research was then to gain a better understanding of the I processes in a semi arid climate zone. The study was conducted in a nearly closed canopy, forty two-year-old pure and evenaged F. rotundifolia afforestation located in the Chitgar Forest Park of Tehran, Iran. Cumulative GR for 22 rainfall events was 91.5 mm. Cumulative I during the measurement period for F.rotundifolia were 16.1% corresponding to the mean net rainfall loss of 14.7 mm. F.rotundifolia in leaf (LP), and leafless periods (LLP) intercepted 21.1%, and 8.8% of GR, respectively. On the event-based (each GR), average I:GR in F.rotundifolia within LP, and LLP periods were 24.6%, and 9.7%, respectively. Negative logarithmic correlations were observed for LP (R2 = 0.62), and LLP periods (R2 = 0.19). The result of this research demonstrates I an important component of the GR that reduces the amount of water that reaches the forest floor.

Afforestation, Fraxinus rotundifolia, Rainfall interception, Semi arid climate.