عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Background and objective: Nutrient cycles in forests are tightly linked to the hydrological cycle because water acts as the main solvent and transporting agent for nutrient from the aboveground tree canopy to the underlying soil. The aim of this research was to evaluate the monthly and annual changes in chemical properties (calcium, sodium and potassium) of the canopy and litter leaching of hornbeam (Carpinus betulus L.) trees during a year compared with nutrients in rainfall (RF).
Material and Methods: This study occurred from January 2012 to February 2013 in a mixed natural stand at the Shastkolate Forest research Station of the University of Gorgan with similar allometric characteristics. For sampling of RF, throughfall (TF) and litterfall (LF) chemistry. RF, TF and LF were sampled on an event basis within a year. The collectors were emptied after each incident rainfall (as soon as rain ceased) and were thoroughly rinsed with deionized water and dried before being replaced. To analyze the chemical content of RF, TF and LF, samples were transported to the laboratory of Gorgan University and stored at 4 ºC. The concentration of sodium (Na+), potassium (K+) and calcium (Ca2+) were determined by flame photometer. In order to compare amount of nutrients in TF and LF with RF and monthly nutrient dynamics of TF and LF, we used t-test analysis and the one way variance analysis.
Results: Results showed that Na+ amount in TF (116.37 kg ha-1year-1), and K+ and Na+ amounts in LF (158.45 and 78.79 kg ha-1year-1), were significantly lower than K+ and Na+ (217.72 and 172.82 kg ha-1year-1) in RF (p<0.05). Also amounts of nutrient leaching of TF and LF in various months were different significantly. The highest leaching amounts of Na+, K+ and Ca2+ were observed for TF, 24.51, 58.30 and 3.14 kg. ha-1, respectively. However highest amounts of Na+ and Ca2+ were measured in October for LF; 19.93 and 4.17 kg. ha-1, respectively. Also the lowest leaching of Na+, K+ and Ca2+ of TF (0.84, 3.22 and 0.15 kg ha-1 respectively) and LF (0.45, 0.52 and 0.03 kg ha-1 respectively) were measured in September.
Conclusion: In this complex process, in crown cation exchange, the absorption tendency of hornbeam crown was higher than its cation diffusion from leaf and branch tissues, so hornbeam crown tend to absorb nutrition from RF to remove its nutrient need.
Key words: Crown leaching, litter leaching, monthly dynamics of base cations, hornbeam species.