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UBC Theses and Dissertations

Dark soils of the Victoria area, British Columbia Broersma, K.


Seven soils with deep surface horizons high in organic matter occurring in south-eastern Vancouver Island in an unique environment were elucidated. The climate is similar to that of the northern Mediterranean. The vegetation consists of a grass and Garry oak (Quercus garryana) parkland on the more xeric sites. This vegetation is believed to be part of a biosequence of grass, Garry oak and Douglas fir (Psuedotsuga menziesii). Four sites were located under vegetation consisting of grass and scattered Garry oak, two sites under Garry oak and one under Douglas fir. In the first paper, Dark Soils of the Victoria Area, Vancouver Island I Environment, Morphology and Genesis, the soils and the environment are described. All the soils were classified into the Canadian and American Systems of Soil Classification. The soils were all classified as Sombric Brunisols except for the one under Douglas fir which was classified as a Sombric Podzol according to the Canadian System of Soil Classification. In the second paper, Dark Soils of the Victoria Area, Vancouver Island, II Physical, Chemical, Mineralogical Properties and Genesis, the results of the physical, chemical and mineralogical analysis are discussed. The soils are coarse textured and are all characterized by high amounts of organic matter in the surface horizon. The organic matter has an influence on many of the soil properties. Most weathering in these soils occurs in the surface horizons. In the third paper. Natural Organo-Mineral Complexes in Some Sombric Soils of the Victoria Area, Vancouver Island, the natural complexes of surface horizons were separated and studied. The separates in this study included: coarse silt (50-20M), fine silt (20-2u), coarse clay (2-0.2y) and fine clay (<0.2y). Most of the soils organic matter was found to be associated with the fine silt and coarse clay fractions. The amount of organic matter per centimeter square in the coarse and fine clay was found to be nearly constant. The finer fractions were associated with the more humified organic matter. The importance of the binding or bridging cations were found to be in the order: Al, Ca, Fe, Mn, Cu, Zn = Mg in these soils.

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