temporal stability of throughfall spatial pattern under individual oak trees in the zagros region (case study: neighboring forests of ilam)

spatio-temporal variability of throughfall (tf) has an important role on the biogeochemical processes,soil, watershed hydrology as well as the nutrient cycle in forests. spatial distribution and temporalstability of tf patterns by five individual persian oak trees (quercus brantii var. persica) in thezagros forests of western iran, ilam, was quantified. sixteen tf manual gauges were placed beneaththe five selected tree canopies in the eight geographic directions and the gross rainfall (gr) wasmeasured by the mean of six homemade gauges records placed in an open area adjacent to the studysite. rainfall interception (i) was indirectly estimated as the difference between gr and tf. themeasurements were recorded during three months from end of december 2010 to beginning of april2011. during this period, 24 rainfall events with cumulative depth of 302.4 mm was collected, ofwhich on average 14.3% evaporated as i or expended as canopy storage by individual persian oaktrees. less than 6% of sampling points in the time stability plots deviated consistently (α= 0.05) fromthe mean normalized tf, meaning lower heterogeneity of tf compared to other studies on the foreststands. moreover, generally ranking of tf collectors of time stability plots confirmed lower tfconcentrations near the tree trunks for individual persian oak trees. time stability plots in the currentstudy were appeared a useful tool to quantify tf distribution of individual persian oak trees.