RESEARCH ARTICLE OPEN ACCESSorientalis Lipsky), has been degraded dramatically due to the industrial over exploitation of wood and livestock overgrazing. ) and Ca 2+ (0.9 mg L -1 ) were higher (for both elements, p = 0.001) in the TF of P. abies compared to those of F. orientalis (6.8 and 0.5, mg L -1 , respectively) and GR (3.2 and 0.37 mg L -1 , respectively). Conversely, mean P concentration was doubled (p = 0.022) in the TF of F. orientalis (11.1 mg L -1 ) compared to GR (5.8 mg L -1 ). Research highlights: P. abies plantations may provide a solution for reforestation of degraded F. orientalis forests of northern Iran, yet how P. abies plantations differentially affect the quality and quantity of rainfall reaching subcanopy soils (TF) compared to F. orientalis is unknown. Understanding the connection between hydrological processes and nutrient cycling in forest ecosystems is crucial for choosing the appropriate species to rehabilitate the degraded indigenous forests with nonindigenous species.

Aim of study: To measure the nutrient leaching from canopy and the O layer in a natural oriental beech (Fagus orientalis Lipsky) forest and a Norway spruce (Picea abies) plantation.Materials and methods: From mid-July to early November, 2013, we measured throughfall (TF) (n=45), stemflow (SF) (n=12) and leaching from the O layer (n = 30) in a 0.5 ha sample plot in the Caspian region, Mazandaran province in northern Iran.Main results: Concentrations of PO43-, Na+, Mg2+, Ca2+ and K+ in the throughfall and the O layer in both beech and spruce forests significantly increased relative to gross rainfall. Concentrations of Ca2+ and Na+ in TF and SF were significantly higher in the spruce forest compared with the beech forest. Furthermore, in both forests, cumulative fluxes of all studied elements (with the exception of NH4+ and NO3-) during the study period were statistically different from those of GR (P<0.05).Research highlights: This study demonstrates that changing from a natural beech forest to a spruce plantation significantly alters nutrient fluxes exiting the canopy and the O layer. This information provides essential information on how planting exotic species will affect nutrient cycles in this region.Keywords: Beech forest; Norway spruce plantation; Throughfall; Nutrient leaching; O layer.