Differences in Rainfall Interception during the Gro wing and Non-growing Seasons in a Fraxinus rotundifolia Mill. Plantation Located in a Semiarid Climate

Abstract

We estimated the rainfall interception loss ( I ), canopy storage capacity ( S ), the ratio of mean evaporation rate from the wet canopy ( E ) over the mean rainfall intensity ( R ) (mm h -1 ) ( R E / ), and free throughfall coefficient ( p ) in a Fraxinus rotundifolia Mill. stand located in an afforested Park land in a semiarid re gion of Iran. For each storm event, I was calculated as the gross rainfall ( GR ) minus throughfall ( TF ). S was estimated by indirect methods: the minimum, the mean, and the Ga sh and Morton. Fifty-five rainfall events were recorded (cumulative GR 197.2 mm), with 31 events occurring during the growing season (total GR 88.0 mm) and 24 events measured during the non-gro wing season (total GR 109.2 mm). The mean ratio of I to GR equalled 39.2% during the growing season vs . 23.9% during the non-growing season. For the grow ing season, S was estimated to be 0.27, 0.21, and 0.23 mm using the m inimum, mean, and Gash and Morton methods, respectively. For the non-growing season, these values were estimated to be 0.17, 0.13, and 0.15 mm, respectively. During the growing and non-growing seasons, R E / were estimated to be 0.13 and 0.11, respectively, with t he corresponding p values of 0.39 and 0.52. The loss of the leaves resulted in decline in I , S , and R E / , and increase in p . For semiarid regions, these values are useful for solvi ng some water management problems. Keywords : Canopy storage capacity, Free throughfall coeffic ient, Seasonal variability.