UBC Theses and Dissertations
Soil erosion, water quality and revegetation at a sub-alpine ski area development McTavish, Robert Bruce
Earth clearing activities in subalpine areas on the west coast of British Columbia can lead to serious soil erosion and subsequent deterioration in physical stream water quality. This study undertook to measure soil losses on unvegetated slopes, sediment discharge into waterways and methods of vegetative erosion control. This study took place at Hemlock Valley Ski Resort which is located in the mountain-hemlock biogeoclimatic zone on the west coast of British Columbia. Quantification of soil loss on unvegetated slopes using a portable rill meter measured soil losses of 605 t ha¹ over a four-month period and a total soil loss of 1 104 t ha⁻¹ over a twenty-six-month period. This corresponded to measured sediment loading in surrounding waterways of up to 571 mg L⁻¹ of suspended solids and downstream movement of sediment of 120.6 tonnes per hour. Testing of twenty-one agronomic grasses and legumes for their ability to establish adequate ground cover to control erosion, resulted in two recommended seed mixes. For dry areas with well drained soils, the species giving highest observed ground cover were tetraploid perennial ryegrass, redtop bentgrass, penncross bentgrass and creeping red fescue. The species giving highest observed ground cover on areas with topsoil intact and poorer drained soils were hard fescue, annual ryegrass, orchard grass and slender wheatgrass. In most species increases in the rates of fertilizer application from 150 to 300 kg ha⁻¹ (12-20-20) resulted in an increase in observed ground cover. A native sedge Carex mertensii was also tested under both laboratory and field conditions. Germination tests in the laboratory gave a maximum germination of 97.5% when tested on top of moist blotters with a five-day prechill and seed wings on and temperature alternating at 30°C on 12-hour day and 20°C on 12-hour night. Field experiments carried out on a site previously shown incapable of supporting agronomic grasses and legumes showed a maximum observed ground cover of 28% with Carex mertensii applied at a seeding rate of 50 kg ha⁻¹ and 12-20-20 fertilizer at 600 kg ha⁻¹.
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