ORIGINAL PAPER Relationships between local stand density and local species composition and nutrient content in the topsoil of pure and mixed stands of silver fir (Abies alba Mill.) Jaroslaw G. Paluch • Piotr Gruba Received: 12 May 2009 / Revised: 18 November 2009 / Accepted: 9 December 2009 / Published online: 7 January 2010 Ó Springer-Verlag 2010 Abstract This study examined topsoil samples from the humic mineral horizon in four pure silver fir (Abies alba Mill.) and five mixed stands with beech (Fagus sylvatica L.), spruce (Picea abies L.; Karst.) and pine (Pinus syl- vestris L.). In every stand, 60–70 sampling locations were chosen using a stratified random scheme that represented a gradient in local stand density and local species composi- tion. One working hypothesis was that stand density and species composition affect the content of nutrients in the mineral humic soil horizon. Specifically, the analysis sta- tistically tested for relationships between general and spe- cies-specific local stand density measures (basal area, sum of tree diameters weighted by distance, canopy openness) and the contents of total C, total N (in four stands), base cations (Ca 2? , Mg 2? ,K ? , Na ? ) and Mn 2? (in nine stands). A considerable variation in nutrient concentrations was observed; the coefficients of variation ranged from 0.21 to 0.38 for N, from 0.20 to 0.94 for the sum of base cations and from 0.56 to 0.95 for Mn. However, no clear rela- tionship emerged between local stand density and the concentration of N and base cations; in five stands, man- ganese showed a negative correlation with local stand density. In the mixed fir-beech stand, significantly higher concentrations of Ca, K and Mn were found in the vicinity of beeches, and species-specific stand density explained up to 15, 29 and 34% of total variation in the content of these elements, respectively. Similar tendencies also appeared in the mixed stands with pine, although the relationships were weak. The results obtained for two fir-spruce stands were ambiguous. In sum, in the stands studied, small canopy gaps and inter-crown openings might not be considered ‘‘nutrient hot spots’’, and the admixed species, except for beech, had an insignificant effect on nutrient content in the humic mineral horizon. Keywords Forest soils  Micro-site  Stand heterogeneity  Mixed stands  Nutrients Introduction In forest ecosystems, nutrient cycling is governed by a number of inter-related processes and factors (Augusto et al. 2002). The distribution of the above- and below- ground organs of trees and other plants that build forest communities is characterised by a discontinuity resulting from their spatial distribution and the architecture of their crowns and roots (Baldocci and Collineau 1994; Fitter 1994). This heterogeneity may cause patches varying in local stand density to differ in terms of the basic determi- nants of nutrient turnover: interception of precipitation in crowns, canopy throughfall (Raat et al. 2002; Staelens et al. 2006; Dalsgaard 2007) and stemflow (Parker 1983; Beier et al. 1993; Koch and Matzner 1993), topsoil temperature and moisture (Sanesi and Sulli 1973; Gray et al. 2002; Clinton 2003; Ritter et al. 2005), litterfall (Hirabuki 1991), dead biomass accumulation (Liski 1995), nutrient uptake by the roots (Caldwell 1994) and soil microbial community structure (Saetre and Ba ˚a ˚th 2000) and activity (Kanerva and Smolander 2007). Communicated by A. Merino. J. G. Paluch (&) Department of Silviculture, University of Agriculture, Al. 29 Listopada 46, 31-425 Cracow, Poland e-mail: jppaluch@pro.onet.pl P. Gruba Department of Forest Soil Science, University of Agriculture, Al. 29 Listopada 46, 31-425 Cracow, Poland 123 Eur J Forest Res (2010) 129:509–520 DOI 10.1007/s10342-009-0348-5