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The aim of this research was to estimate the ecohydological parameters of the canopy covers including estimated canopy saturation point (P´G Estimated), canopy storage capacity (S), the ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity ( ), free throughfall coefficient (p), computed canopy saturation point (P´G), and stemflow funneling ratio (F) of a Picea abies plantation in Lajim, Mazanderan province, north of Iran. To measure throuhgfall (TF), 45 rain-gauges were installed beneath the crown of the stand. Stemflow (SF) was measured using the average of 12 individual trees equaled to the SF amount. Over the measurement period, the cumulative percentage of TF, SF, and rainfall interception (I) were 41.0%, 5.1%, and 53.9%, respectively. The abovementioned ecohydrological parameters were found to be 4.2 mm, 3.54 mm, 0.38, 0.18, 5.90 mm, and 4.6, respectively. The ecohydrological parameters should be considered while converting natural stands to plantations of exotic tree species as this altering would be alter soil humidity, soil pedogenesis, and forest floor composition.

The study aims to estimate the canopy storage capacity (S) and the ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity (), and the free throughfall coefficient (p) of Pinus eldarica (44 years-old-age) afforestation using three regression-based methods (Minimum, Gash and Morton and Mean methods) in the Chitgar Forest Park, near Tehran, with a semiarid climate zone. To measure gross rainfall (GR), 10 rain gauges were fixed in an open space nearby to the stand and throuhgfall (TF) was measured during a year using the 50 rain gauges randomly placed underneath the canopy cover. Rainfall interception (I) was computed as the difference between GR and TF. Fifty rain storms were recorded with a cumulative depth of 262.5 mm. The TF and (TF:GR)% were recorded 69.5% and 53.2% of the rainfall event on the cumulative-based, and event-based (each GR), respectively. Positive logarithmic correlations were observed between (TF: GR)% and GR during the study period (TF:GR = 16.598 ln GR + 35.494; R2 = 0.630). For dry (from May to November) and wet periods these values corresponded to 0.988 and 0966 by positive linear correlations. The mean value of S,, and p were estimated 1.23 mm, 0.10, and 0.19, respectively. Since measurements of the amount of GR and I are expensive and time-consuming in semiarid and arid regions, and attended measurements in the field are currently carried out, thereto, regression models for estimating I and its components, e.g., S, p, and coefficients can successfully been applied.

Changes in rainfall interception and consequently in water balance cause essential effects on reforestation by indigenous and exotic tree species in the degraded areas of the Caspian forests. The aim of the present study was to compare the interception of Quercus castaneifolia, Acer velutium, and Pinus brutia plantations during the growing season in Darabkola Forest in eastern part of Mazandaran province in northern Iran. The amount of rainfall (GR) and throughfall (TF) were measured from May to November 2012 by 6 and 20 polyethylene manual gauges with 8 cm diameter each. The rainfall interception was estimated as the difference between TF and GR. During the measurement period 20 rainfall events were recorded. The amount of cumulative GR depth was 346.5 mm. Moreover, the cumulative rainfall interception of Q. castaneifolia, A. velutium, and P. brutia were 86.2 mm, 107.9 mm and 178.3 mm, respectively. The results showed that the rainfall interception was higher during the dry season, from April to September. In addition, significant correlations were observed between rainfall interception and the relative interception for the three plantations (r2 =0.781, 0.716 and 0.618 for Q. castaneifolia, A. velutium and P. brutia, respectively). It is concluded that estimating the amount of rainfall interception is crucial for selecting adapted species for reforestation in the Caspian forests. It is also a prerequisite for calculation of the water balance within reforestations.

The aim of this study was to estimate the individual tree-based 1) canopy water storage capacity (S), 2) ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity () by the Pereira method, and 3) direct throughfall coefficient (p) for Cupressus arizonica trees. The trees wereafforested in the Chitgar forest park in Tehran which is classified as a semiarid region. Measurements were carried out from February 2011 to February 2012. To measure the gross rainfall (GR), six rain-gauges were installed in an open space adjacent to the trees. Throughfall (TF) was measured using a number of twenty rain-gauges located under the crown of five individual trees. Rainfall interception (I) was calculated as the difference between GR and TF. During the measurement period, 55 rainfall events were recorded with a cumulative depth of 234 mm. The C. arizonica trees intercepted 21.8% and 32.1% of the incident rainfall on cumulative-based and event-based (each GR) manner, respectively. Positive and negative power correlations were observed between I and GR (r = 0.89)as well as between(I: GR) % and GR (r = 0.69) for the mean value of five individual trees. Mean values of S,, and p were estimated as 0.38 mm, 0.14, and 0.46, respectively. I and its elements (), S, and p as well as transpiration of trees are, therefore concluded as necessary parameters to be considered when selecting suitable species for afforestation projects in the arid and semiarid zone. In addition and as a key parameter for calculating I, S can be optimally estimated by Pereira method which is exclusively proposed for tree-based measurements.

The aim of this research was to estimate the ecohydological parameters of the canopy covers including canopy storage capacity (S) using the Pereira method and the direct throughfall coefficient (p) of individual trees of Pinus eldarica planted in the Chitgar Forest Park with a semiarid climate. To measure GR, six rain-gauges were installed in an open area neighboring to the trees. Throuhgfall (TF) was measured using the twenty rain gauges randomly located underneath the crown of the five individual trees. Rainfall interception (I) was calculated as the difference between GR and TF. From January 2011 to January 2012, 224 mm of cumulative GR in fifty-one rainfall events was recorded. P. eldarica trees intercepted 35.9% and 47.5% of the incident rainfall on cumulative-based, and event-based (each GR), respectively. The mean value of S estimated by the Pereira method, and p were found to be 0.77 mm (SE ± 0.08), and 0.44 (SE ± 0.07), respectively. The results indicated that I allocated a considerable portion of GR in P. eldarica trees in arid and semiarid regions. Hence, I should be considered while calculating the water budget for P. eldarica plantations. S which is a critical parameter for controlling I can be usefully estimated by a sole newly proposed method by Pereira for individual trees.

The main goal was to measure interception loss (I) and to determine the contribution of the meteorological parameters as well as rainfall size in Pinus eldarica Medw. and Cupressus arizonica Green. in the arid climate zone of Iran. The selected trees were located inside a forest plantation in a dry area at Semnan province, where mean annual precipitation, and air temperature are 127 mm and 16˚C, respectively. The gross rainfall (GR) was measured by the mean of three hand-made collectors placed in an open area neighboring to the chosen trees. Eight throughfall (TF) collectors were positioned beneath the tree canopies to average into TF mean per species. Measurements were made on a rainfall event basis in a year, from March 2009 to March 2010. We investigated the correlations between intercepted rainfall (I:GR) with rainfall size (GR) and combination of the daily meteorological parameters of wind speed (WS), relative humidity (RH), evaporation (E) and air temperature (Ta). Averaged over all 26 events during a one-year measurement, approximately 44.6% of GR for P.eldarica and 32.6% for C. arizonica did not reach the soil surface beneath the afforestation and lost through evaporation process. The results showed that rainfall size was highly correlated with I:GR. However combinations of the meteorological parameters of Ta, RH and E improved the suggested models for estimation of I:GR. We concluded that the meteorological parameters could be usefully applied for estimation of interception of P. eldarica and C. arizonica planted in arid climate zone and in particular near meteorological stations like urban plantations.

Measurements of gross rainfall (GR), throughfall (TF), and stemflow (SF) were conducted inside oriental beech (Fagus orientalis Lipsky) and oak (Quercus castaneifolia C.A.M.) forests in Kheyrud Forest Station of University of Tehran. GR was collected by means of three manual collectors placed in neighboring open areas from the study plots. TF was collected by thirty five TF manual collectors positioned randomly underneath the trees canopies. SF was collected from beech and oak trees, with different diameters by the spiral-type SF collection collars installed at diameter at breast height. Rainfall interception (I) was calculated indirectly as the difference between GR and sum of the TF and SF. The cumulative GR depths of 13 and 14 events for oak and beech forests were 297 and 270 mm, respectively. On the event scale average ratios of TF:GR, SF:GR, and I:GR in the oak forest were 75.50%, 0.26%, and 24.24%, respectively, whilst those of the beech forest were 71.30%, 2.70%, and 26%. Strong positive correlations were observed between ‏TF and GR in both oak and beech forests. Results showed fairly strong negative relationships between I:GR and GR in both forests. Rainfall interception contributes a notable amount of incident rainfall in the oak and beech forests and its measurement, therefore, is an essential element while assessing water balance on the catchment scale.

The main aim of the present research was to measure interception (I) by individual trees of Pinus eldarica and Cupressus arizonica that extensively planted in afforestation projects of the arid zone in Iran. The selected trees were located inside a forest plantation in a dry area at Semnan province, where mean annual precipitation and air temperature are 127 mm and 16˚C, respectively. The gross rainfall (GR) was measured by the mean of three hand-made gauges placed in an open area neighboring to the chosen trees. Five individual trees were selected for measurements of throughfall (TF). Eight TF collectors were positioned beneath the tree canopies in the four main directions to average into TF mean per species. I was calculated as the difference between GR and TF for each tree and I was finally averaged into the means of P. eldarica and C. arizonica. Measurements were made on a rainfall event basis during 2009 summer season, from March to October. The cumulative GR depth of 12 events was 37.9 mm; I (P. eldarica): 17.2 mm, and I (C. arizonica):12.3 mm. On the event scale average ratios of I:GR were 68% (1.4 mm per event) and 55% (1 mm per event) for P.eldarica and C.arizonica, respectively. Strong positive correlations were observed between I and GR (P.eldarica, R2=0.94; C.arizonica, R2=0.87). Our measurements suggested that intercepted GR or I:GR ratio by the canopies, and loss through evaporation decreased, as the size of rainfall events increased. The results showed that interception is a significant component of the seasonal water balance in the afforestation of the arid zone of Iran.