Plot-scale spatial patterns of soil water content, pH, substrate-induced respiration and N mineralization in a temperate coniferous forest

Samples of two perpendicular transects from an even-aged Norway spruce ( Picea abies) forest were used for geostatistical analysis of forest floor water content (WC), pH, substrate-induced respiration (SIR, a measure of microbial biomass), and N mineralization (Nmin). Nmin data did not fulfil the stationarity assumptions of geostatistics and had to be detrended prior to analysis. All variables exhibited spatial structure. The degree of spatial dependence was generally high (60%-95%). pH and SIR were isotropically distributed; WC and Nmin were anisotropic. Three different scales of spatial variability were detected at the site. (1) A fine-scale pattern with ranges < 1 m that was attributed to retarded decomposition, poor chemical and structural diversity of P. abies litter, and lacking bioturbatic activity of earthworms. (2) A mesoscale pattern was indicated by sinoidal periodicity of most variograms, with inflection points every 1.0-1.5 m. This periodicity probably reflected the influence of regularly spaced tree individuals. (3) Nmin and WC exhibited unexplained long-range trends that exceeded transect length. (C) 1999 Elsevier Science B.V. All rights reserved.