Is canopy interception increased in semiarid tree plantations? Evidence from a feld investigation in Tehran, Iran

Abstract

From 30 January 2011 to 30 January 2012, we measured the rainfall interception (I) and canopy storage capacity (S ) ofindividual trees of Pinus eldarica and Cupressus arizonica planted in the Chitgar Forest Park near Tehran, Iran. Gross rainfall (GR) inthis semiarid region was measured using the mean of 6 plastic rain gauges placed in an open area adjacent to the trees. To measurethroughfall (TF), 20 plastic rain gauges were installed beneath the crowns of 5 individual trees of each species. I was calculated as GRminus TF. S was estimated using indirect methods: the minimum, Gash and Morton, mean, and Pereira methods. Te cumulative meanvalues of relative percentage of I (I:GR) for P. eldarica and C. arizonica trees averaged 44.2% and 34.4%, respectively. Signifcant negativerelationships were observed between the percent of I:GR and GR for P. eldarica (R2 = 0.63) and C. arizonica (R2 = 0.67) trees. For P.eldarica , S was estimated to be 1.10 mm, 1.00 mm, 1.09 mm, and 1.05 mm using the minimum, Gash and Morton, mean, and Pereiramethods, respectively. For C. arizonica , the corresponding values are 0.58 mm, 0.52 mm, 0.56 mm, and 0.55 mm. Tis study proposesthat in this climate dominated by small storms, planting C. arizonica is preferable to planting P. eldarica . However, the diferences in thetranspiration of these species should be quantifed. Our results also indicated that the I value in this semiarid climate was higher thanthat of a humid climate.