Chemical content and seasonal variation of throughfall and litterflow under individual trees in the Hyrcanian forests of Iran

We assessed the effect of seasons and the tree species velvet maple (Acer velutinum Boiss), Hainbuche hornbeam (Carpinus betulus L.) and chestnut-leaved oak (Quercus castanefolia C. A. Mey.; Fagaceae) on nutrient fluxes (Na+, K(+)and Ca2+) in throughfall (TF) and litter flow (LF) from January 2012 to February 2013. Potassium (K+) and calcium (Ca2+) in total TF and LF over the measurement period significantly differed between 3 the species (p < 0.05). Maple and oak trees had significantly higher fluxes of K+ and Ca2+ in their TF, respectively. The average quantity of nutrients in LF was significantly higher in the leafy season than in the leafless season for all cations except for Na+. Under velvet maple trees, the average flux of nutrients (Na+, K+ and Ca2+) in TF was significantly higher than LF. Lastly, leaching of potassium (K+) and calcium (Ca2+) in LF during the measurement period was significantly lower than TF under the hornbeam trees. Our results suggest that different tree species may impact the nutrient availability and possibly the sustainability of Hyrcanian forests. Further research is needed to determine how managing different species will affect the long-term nutrient status of these forests.