Selected biological and chemical properties of forest floors across bedrock types on the north coast of British Columbia

We examined some of the factors related to nutrient availability of forest floors developed over saprolitic and colluvial mineral soils of four bedrock types (granodiorite, gneissic diorite, schist, and limestone) on the outer northern coast of British Columbia. All sites were relatively well drained with old-growth coniferous forests. Forest floor morphology was quite similar across sites, with friable, moderately aggregated horizons dominating the profile. There were significant differences in concentrations of total nitrogen, available phosphorus, total sulphur, and condensed tannins across bedrock types. We found detritivores such as sowbugs, millipedes, and potworms across all sites. We could not detect differences in turnover rates (via laboratory respiration) of organic matter between bedrock types. Turnover rates instead were negatively correlated with forest floor carbon and total canopy cover. Overall, forest floor properties were quite similar across the range in parent materials because of the strong influence of climate and vegetation on soil development.