The Spatial Variation of pH in the Mor Layer of Some Coniferous Forest Stands in Northern Sweden

The spatial pH-variation is shown to be slightly decreasing when comparing different coniferous stands in northern Sweden with a 200 m(2) respectively a 2 m(2) sample plot within a stand. The result indicates that the pH-variation in the mor layer to a great extent is to be found in a plot <2 m(2). The hypothesis of Hesselman (1926) and Bergholm et al. (1985) that few samples should be enough for a reliable pH-determination of a stand is questioned and critically discussed. The number of samples required to obtain a pH-determination with an accepted accuracy is discussed. The spatial pH-variation from the plots in the study suggests that approximately 12 samples are required to get a mean error of 2% at 95% confidence limits. But one should be aware of that, even with 12 samples, the difference between the highest and lowest value in a 2 m(2) plot will be about 0.6 pH-units.