The impact of canopy composition on the nutritional statusof an admixed spruce and beech forest at Solling,central Germany

摘要: It was hypothesised that in mixed spruce-beech forest ecosystems the heterogeneity canopy composition may create different micro-sites (units) forest floor and mineral soil with ecological characteristics. Therefore, types of canopy compositions (canopy classes) were used to identify variability water and element fluxes (via throughfall litterfall), soil solution chemistry, litter decomposition respiration. The investigation carried out a mixed sprucebeech stand in Solling, central Germany. Two plots selected for this study representing most contrasting cases forests types, which i) site greatly dominated by spruce trees (the spruce plot, SDP) two beech in-between ii) a directly neighbouring and having single tree (the plot, BDP). The canopies classified four categories: pure beech, spruce, gap. Throughfall significantly lower major element fluxes were higher under than both plots. This indicated nutrient inputs individual trees driven species-specific properties canopies and quite independent degree admixture. With the exception K+, showed intermediate inputs via throughfall, compared classes. K+ input, however, greater due to interactions canopies, leading leaching rates for K+. Throughfall main source nutrient inputs, while foliar litterfall input almost equal between sub-plots thus had homogenising effect on annual nutrient fluxes beech-spruce stands. Differences chemistry classes were mainly observed floor top layers. Significant effects composition pH (CaCl2) values of detected between gap (significantly higher) (significantly lower) sub-plots in plot (SDP). (lower under spruce) (higher concentration elements could explain theses differences. In spite of inputs, masses organic matter (humuslayer) different sub-plots for plots, SDP BDP. Differences most pronounced gap sub-plots (spruce ≥ beech ≥ gap). The solution at 10 cm depth higher pH values sub-plots, spruce sub-plots. This finding be linked via sub-plots. A significant rate of litter decay CO2 efflux beech dominated (BDP). Here, showed significantly remaining end incubation period (about one year after incubation) spruce sub-plot. indicate early stage the decomposition process not governed given canopy composition. sub-plot soil respiration, sub-plot. An estimation the root-associated production revealed considerably root respiration other BDP. In total, it shown able to specific biogeochemical patterns investigated mixed forest. However, impact an individual spruce beech-dominated induced obviously higher degrees spatial respect respiration compared to individual site.