ASSESSMENT OF THE RISK OF NITROGEN SATURATION IN A MOUNTAINOUS FIR STAND

The risk of N saturation was assessed in a mountainous fir stand in central Greece. The motivation of the research was the high content of N in soils as well as the low ratio of C/N in the FH soil horizon. Specifically, the stocks of N in both organic and mineral soil layers at a total depth of 80 cm were found 10,864 kg ha(-1) and the ratio of C/N in the FH soil horizon 19. The ecological parameters measured to assess the N saturation status were the N fluxes in throughfall deposition, the concentrations of nitrate N in soil solution and the N content in current and second year needles over time. The time series statistical analysis showed that the fluxes of inorganic N in bulk and throughfall deposition did not have a significant trend and did not exceed the limit set in literature. It was also found that the average concentrations of nitrate N in soil solution were low although the values varied a great deal. Also the content of N in current and second year needles did not change significantly over time. It can be concluded that the fir stand is not saturated with N. The low concentrations of inorganic N in throughfall deposition, the dense ground vegetation and the stability of organic compounds may have contributed to the N retention in soil.