Nitrogen cycling in a mature mountainous beech forest

Abstract

The nitrogen cycle in a mature, mountainous European beech (Fagus sylvatica) forest in Greece was examined for two hydrological years, 2001–2002 and 2002–2003. Bulk deposition was 1383 mm in 2001–2002 and 2392 mm in 2002–2003. Winter temperatures were mild in the first year and low in the second year. Despite these climatological differences, the inorganic N inputs to the forest floor, by means of throughfall and stemflow, were quite similar for the two years, i.e. 12.4 and 14.6 kg ha yr. Litterfall production was significantly (p < 0.05) higher in the second year but the N amounts in litterfall did not differ. The ratio of N/P in foliar tissue did not change significantly in 2003 compared with ratio values in the last years. The N amounts used for the annual stem and branch increments are rather high preventing, in this way, some nitrogen from being recycled in the near future. The total soil N content to a depth of 80 cm amounted to more than 5000 kg ha, and the C/N ratio in the Oh horizon was approximately 15 but the beech forest did not appear susceptible to N leaching. The concentrations of ammonium and nitrate N in stream water did not reach high values reported in the literature, and did not differ significantly in the two hydrological years. The fluxes of inorganic N in throughfall plus stemflow were higher than those in stream water indicating N retention in soil. Another reason for N retention in the ecosystem is probably the large difference between N requirements and uptake indicating N deficiency. Despite the maturity of the beech trees, the low C/N ratio in the Oh horizon and the relatively high N content in soil, the forest can be considered to be neither saturated nor having reached a N saturation transition stage.–1–1–1

Cloud water interception and element deposition differ largely between Norway spruce stands along an elevation transect in Harz Mountains, Germany

“…The element concentrations were detected separately for each sampler and sampling period and averaged over the whole study period by weighting the concentrations by the water volume in the samples (volume-weighted means; Köhler et al, 2006;Michopoulos et al, 2008). The concentrations of inorganic nitrogen [ammonium (NH 4 + ) and nitrate (NO 3 À )] were determined by continuous-flow injection colorimetry (Cenco/Skalar Instruments, Breda, The Netherlands) with the Berthelot reaction for NH 4 + detection and the copper-cadmium reduction method for NO 3 À detection.…”

“…The concentrations of inorganic nitrogen [ammonium (NH 4 + ) and nitrate (NO 3 À )] were determined by continuous-flow injection colorimetry (Cenco/Skalar Instruments, Breda, The Netherlands) with the Berthelot reaction for NH 4 + detection and the copper-cadmium reduction method for NO 3 À detection. The element concentrations were detected separately for each sampler and sampling period and averaged over the whole study period by weighting the concentrations by the water volume in the samples (volume-weighted means; Köhler et al, 2006;Michopoulos et al, 2008).…”

Controlling factors of temporal variation of soil respiration in a natural beech forest as revealed by natural incubation experiments

“…This might provide an explanation for the correlation between SON and Rs in our study. Therefore, in addition to the C cycle, N also plays an important role in the soil in beech forests (Jussy et al 2004;Kitzler et al 2006;Michopoulos et al 2008). Our model also suggests that N-loss might result from soil warming and emphasized the interaction between changes in N cycling rates and soil water flux in determining potential inorganic-N loss.…”

Impact of regional climatic conditions on tree growth on mainland Greece

“…Detailed characteristics of the plots regarding vegetation status, soil conditions, etc. are reported in Michopoulos et al (2008Michopoulos et al ( , 2015. The data set regarding tree growth was generated according to the guidelines of the ICP-Forests tree growth manual (Dobbertin and Neumann, 2016).…”