摘要：

VRANOVA, V., HOLIK, L., ROHLIK, T., REJSEK, K., FORMANEK, P.: Carbon, nitrogen, C/N ratio and their stand heterogeneity in the soil of Norway spruce stands. Acta univ. agric. et silvic. Mendel. Brun., 2010, LVIII, No. 5, pp. 413–416 This work is aimed to determine the eff ect of thinning of young spruce stands in Moravian-Silesian Beskids Mts. on concentrations and relative stand heterogeneity of Cox, Nt and C/N in soil. Concentrations of Cox and Nt were signifi cantly higher in individual horizons of forest humus fl oor. The thinning did not infl uence signifi cantly (P > 0.05) concentrations of Cox, Nt and C/N ratio in particular soil horizons, with the exception of C/N ration in E horizon. Relative stand heterogeneity of the studied soil properties was mostly higher in soil of dense forest stand. The values of relative stand heterogeneity for individual horizons ranged from 3.1 to 61.9 % in case of Cox, from 4.9 to 55.2 % for Nt and from 5.3 to 42.5 % for C/N ratio. Results of this work are useful to predict stand heterogeneity of soil biochemical properties which are known to correlate with especially Cox in soil on studied plots, especially soil respiration and enzymatic activities. soil, thinning, forest, heterogeneity, carbon, nitrogen Norway spruce (Picea abies [L.] Karst.) is one of the most important commercial tree species in European forests. Norway spruce is o en grown in even-aged, single-species stands and managed using a clear-cutting system. Thinning is a regular component of the management program if this species is to reach the dimensions needed for the timber trade (Slodicak et al., 2005). The thinning process is accompanied by a decrease in stand density and leaf area and an increase in light and nutrient avai la bi li ty. This leads to changes in soil temperature, soil water, regime root density, respiration of roots, leaching of dissolved organic matter from canopy, and changes in soil microorganisms (Tang et al., 2005; Bird et al., 2002). Thinning may reduce possible competition between plant roots and saprophytic mi cro or ganisms for water and nutrients and, in turn, enhance decomposition and nutrient cycling in these ecosystems (Slodicak et al., 2005). As thinning aff ects inputs of aboveand belowground biomass, its decomposition and distribution in soil, it is necessary to determine its eff ect on change in heterogeneity of organic compounds in soil. For this reason, we have performed an experiment to determine the eff ect of young spruce stands thinning on stand heterogeneity of soil carbon oxidable (Cox), nitrogen total (Nt) and carbon / nitrogen ratio (C/N) content in particular horizons of Typic Haplohumod. MATERIAL AND METHODS The "Bil Ki" ("White Cross") Experimental Ecological Research Site, where the experiments took place, is located in the Moravian-Silesian Beskids Mts. in the northeastern part of the Czech Republic at 908 meters a. s. l. (N 49°30'10", E 18°32'20"). The region has a subcontinental climate with a typical mean annual air temperature of 4.9°C and mean annual precipitation of 1.100 mm. The number of days with snow cover is 160 per year (Formanek et al., 2008). The experimental 23-years-old Norway spruce stand is located on slightly descending slope. The stand comprises approximately 99 % Norway spruce and 1 % fi r (Abies alba Mill.). Within the experimental stand, two 0.25 ha study plots were established, each diff ering in intensity of thinning: 414 V. Vranova, L. Holik, T. Rohlik, K. Rejsek, P. Formanek the forest dense (FD) and the forest sparse (FS) plots. The thinning of the plots was performed according to Table I. The plots are located side by side and a fence surrounds each of them. The experimental Norway spruce stand was originally established as the 2nd generative stand on an area created by clearcutting the previous 120-years-old Norway spruce forest. Before thinning in 1995, the experimental stand was of the same initial density of 2,830 trees/ ha throughout. Thinning of the FD and FS plots was then performed on a number of separate occasions as shown in Tab

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