LATERAL VARIABILITY IN SOME PROPERTIES OF DISTURBED FOREST SOILS IN SOUTHWESTERN BRITISH COLUMBIA

Abstract

Lateral variability in a variety of physical and chemical properties was studied in the surface 30 cm of mineral soil taken from beneath young (5–12 yr) Douglas-fir plantations established after clearcutting and slashburning, primarily in the Coastal Western Hemlock Zone in southwestern B.C. Of the 19 soil properties considered, pH was the least variable while available P and extractable Ca concentrations and quantities tended to be the most variable. However, the order of variability was not consistent among the five plots studied. Estimation of mean values with an allowable error of 10% at the 95% confidence level would require a very large number of samples for most of the properties studied. Even with an allowable error of 20% at the 90% confidence level, more than 100 samples would be required in some instances. Methods of overcoming this need for a large sample size are discussed. A comparison of within-plot variability to among-plot variability for three situations produced no consistent trends. However, the among-plot variability of high forest productivity plots was greater than that of low forest productivity plots for nearly all soil properties considered. Key words: British Columbia, forest soil, soil chemistry, soil variability