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UBC Theses and Dissertations

The major soils of the Tofino area of Vancouver Island and implications for land use planning and management Baker, Ted Edgar


'The soils resource in the Tofino area of Vancouver Island is considered for land-use planning and management purposes. This was done by completing a series of four studies. The first study describes the study area by looking at those components which were considered to have a major impact on the function of the soils in the landscape. This included geology (bedrock and surficial), soil morphology, depth to water table, vegetation, climate and water quality. The soils exhibit a range of soil development from very little to strongly expressed genetic characteristics including cemented horizons. The presence of many lithologic discontinuities confirms a complex mode of material deposition in the area. The second study is concerned with the physical, chemical and mineralogical properties of the soils. Soil genesis is also discussed. The analyses show a wide range of textures in the soils and varifies the presence of lithologic discontinuities. Pedo-genic processes have changed the structure in some soils by aggregating the Fe and Al oxides into larger sized particles. The soils are low in natural fertility with nutrient cycling occurring primarily in the organic horizons or above restricting layers in the mineral horizons if these are near the surface. Vermiculite is the dominant clay mineral in the surface mineral horizons indicating a weathering environment of moderate intensity. The third study discusses the characteristics and genesis of some placic horizons (thin pans) which have developed in some soils in sand deposits. These horizons exhibit considerable variation in morphology and chemical composition. The primary cementing materials are organic matter (mainly fulvic acid), and Pe which is present as either inorganic amorphous or organically complexed Fe. The morphological characteristics and stability of the placic horizons are dependent upon the amount of OM present and the form in which the Fe occurs. The genesis of these pans is initiated at lithologic discontinuities under differential redox conditions. Diffusion is active in material transport with the pan acting as a template upon which the material is precipitated. The fourth study is an assessment of-the soils for land-use planning and management purposes. Emphasis is given to the identification of processes which control the function of the soils both internally and externally. The soils are grouped into three categories characteristic of the dominant control. The categories are; landscape components, inherent characteristics and genetic features.

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