| Manderscheid, B; Matzner, E: Spatial and temporal variation of soil solution chemistry and ion fluxes through the soil in a mature Norway spruce (Picea abies (L.) Karst.) stand, Biogeochemistry, 30, 99-114 (1995) | |
| Abstract: In this study we investigated the spatial and temporal variation in soil solution chemistry and of water and ion fluxes through the soil in a forest ecosystem. Our aim was to evaluate the relevance of these variations for the accuracy of average area1 soil solution concentrations and ion fluxes with seepagea t 90 cm depth. Twenty spatially distinct ‘subcompartments’ of approximately 1 m2 were established within a mature stand of Norway spruce and ceramic suction lysimeters were installed at depths of 20, 35 and 90 cm. A tensiometer was placed close to each suction lysimeter, and one throughfall sampler was established for each subcompartment. Soil solution samples were analysed for major ions (H+, Nat, Kt , Cazt , Mg*+ , Mnzt , Fe3+,A 13+,C l-, NO,, SO:-). We calculatedw ater fluxes for eachs ubcompartmenst eparately by a numeric simulation of the soil water flux close to the lysimetets. The ion fluxes at each lysimeter were calculated by multiplying the simulated water fluxes with the ion concentrations on a fortnightly base. Averaging these 20 independent ion fluxes gave the area1 average flux and an estimate of its statistical accuracy. The spatial variation of ion concentrations in the soil solution was high with coefficients of variance ranging from 5% to 128%. Part of the spatial variation was related to stem distance. Temporal variation of the concentrations was less than spatial for most ions. The spatial variation of water and ion fluxes with seepage was also substantial; for exam le the fluxes of SOi--S calculated for each subcompartmentr anged from 21 to 119 kg ha- P yr -I , with an arithmetic average of 47 kg ha-’ yr-‘. For HrO, Mg2+, Cl-, and SO:-, the spatial heterogeneity of seepage fluxes was largely explained by the heterogeneity of throughfall fluxes. No such relationship was found for nitrogen. Despite using 20 replicates,t he 95% confidencei ntervals of the averagea nnuala rea1fl uxes with seepagew ere found to be 20-30% for most ions. Key words: forest, ion budgets, seepageoutput, soil solution, spatial variation, throughfall Introduction Numerous papers have been published on soil solution chemistry, ion fluxes with percolation water and on element budgets of terrestrial ecosystems over the last three decades (for overview see Harrison et al. 1989). However, little attention has been given to the problem of spatial variation of soil solution concentrations and water fluxes in the soil and their relevance for the accuracy |
