Dynamics of chemical compositions of throughfall in a natural forest of Fagus orientalis and a Picea abies plantation in the leafed period

The aim of this study was to compare pH, EC, and chemical concentrations of throughfall (TF) (NO₃^-, P, k⁺, Ca²⁺, and Mg²⁺) in a natural stand of Fagus orientalis Lipsky and a plantation of Picea abies in Kelardasht forest, Mazandaran province, Iran. Measurements were conducted from July-2012 to October-2013. Gross rainfall (GR) was measured using four manual collectors in a nearby clearing, and twenty manual collectors, similar to the GR collectors, were located in each stand. Duncan tests suggested that there was no significant difference betweenpH means; however, the EC values were significantly different among GR, TFofF. orientalis and TF ofP. abies. There was a significant difference between NO₃^- concentrations of GR (6.50 ppm) and TF of F. orientalis (3.10 ppm). The amount of P⁺ by F. orientalis (11.08 ppm) was significantly higher than cf. GR (5.80 ppm). The concentrations of K⁺ and Ca²⁺ were higher in the TF of P. abies stand, 13.43 and 0.94 ppm, respectively, cf. TF of F. orientalis, 6.78 and 0.49 ppm, respectively, and GR values, 3.18 and 0.37, respectively. The average inputs of all elements - except Ca²⁺- were significantly difference between TF and GR. The average enrichment of elements -except Ca²⁺- showed no significant changes in the TF of stands and GR. Knowledge of the inputs of nutrients to forest ecosystems is necessary for making a sound and reasonable decision in management and selecting a suitable species for reforestation in derelict areas of the Caspian forests of Iran.