Evapotranspiration from a forest clearcut was measured over two growing seasons as part of a larger study of the microclimate of forest clearcuts and microclimate modification by site preparation. Pinegrass is the dominant species on clearcuts in the dry southern interior and is the major competitor with coniferous seedlings. This paper examines the water use of a pinegrass dominated clearcut and the response of surface conductance to environmental variables. Evapotranspiration was derived from eddy correlation measurements of sensible heat flux and measurements of net radiation and soil heat flux. 419 hours of daytime energy balance data from the summers of 1987 and 1988 were analyzed. A rearranged form of the Penman-Monteith equation was used to calculate hourly mean surface conductances for the clearcut. Leaf area measurements were used to calculate stomatal conductance from surface conductances. Stomatal conductance was modelled using boundary-line and non-linear optimization techniques. The most successful model (R² = 0.71) was obtained using non-linear optimization with stomatal conductance as a non-linear function of saturation deficit at the leaf surface (D₀) and solar irradiance. D₀ was calculated from measured evapotranspiration and surface conductance. Response of stomata to saturation deficit would be expected to be better correlated to D₀ than D measured at a reference height above the canopy. Stomatal conductance was also modelled as a function of D (measured at 1.3 m) and solar irradiance. The resulting model (R² = 0.50) was poor compared to that based on D₀. Saturation deficit and temperature were found to be highly correlated both at 1.3 m above the canopy and at the leaf surface. Use of air temperature in the conductance model caused R² to decrease. No relationship between stomatal conductance and volumetric soil water content was found. Hourly evapotranspiration rates calculated using modelled surface conductances agreed well with measured rates.(R² = 0.89). Evapotranspiration was also modelled using the Priestley-Taylor approach. The mean hourly a for all daylight data was found to be 0.81. This simple model was found to give comparable results to the stomatal conductance based model (R² = 0.85). / Land and Food Systems, Faculty of / Graduate

Geomagnetically Induced Currents (GIC's) in B. C. Hydro's 500 kV transmission system have in the past been responsible for the generation of harmonics of 60 Hz, system voltage drops, and misoperation of relay units. Characterization of the associated magnetic storms' spatial scales would further the understanding of GIC generation in the area, and allow advanced warning of potential problems in future power transmission projects. Data collected in 1984 at four substations were analysed to determine lateral variations in geomagnetically induced earth surface electric fields. Inversion techniques were employed to find a variety of solutions that would reproduce the data. Results suggested that the magnetic storms were larger than the area monitored, and that resultant electric fields seen by a large portion of the transmission grid were uniform. Departures from this uniformity in other portions of the electric field models were felt either to be due to earth induction effects, or in some cases, to be artifacts of the data analysis techniques. An experiment designed to determine the controlling factors behind GIC's is outlined. Considerable effort would be required to explicitly determine all electric fields affecting the transmission system / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The topic of this thesis is the relationship between transportation modes and regional economic development. The objective is to determine the influence of the mode on the pattern of development. The three most significant variables in transmitting the influence are seen to be: the construction pattern and attributes of the transport systems; the resources of the region; and the stage of development of the region. The basis of the relationship is that theoretically and empirically, in a frontier region transportation is one of the most effective and controllable factors influencing industrial investments. The relationship is examined by associating private investments in northeastern British Columbia with the demand and supply of transportation units in the region. The investment statistics are drawn from government publications while the transportation units are documented in a variety of ways. Firstly, the historical development of the networks is discussed. Then, a measure of the road network is developed to simulate the changing relative lengths of the road links over time. Investment in industrial categories in the study region was found to be related to attributes of transport networks, such as rates and frequency. Correspondence with firms in the study area supplied additional information about transportation needs and costs. The empirical data on transportation networks are discussed in terms of theories of industrial location and regional economic development to arrive at explanations of the spatial and temporal distribution of the investment. The conclusions drawn from the study verified that investments in certain sectors of the economy were related to specific transport modes. Investments in some primary industries were dependent on certain transport units supplied by the rail network. Cheaper freight rates, volume and size restrictions and frequency characteristics of the rail mode made it attractive to those industries which traditionally had low value-to-weight ratio goods. Investments in the primary industries were also associated temporally with changes in the rail network. The wood products and paper and allied industries received investments temporally and spatially related to changes in the rail network. Investments in industries linked with these primary industries were also documented showing temporal sequence patterns. The findings demonstrated that in a resource region, transportation units with specific characteristics are desired to facilitate development of resources. Cost was found to be one dominating consideration. Some industries which used the rail system, could have used the road network but it would have cost 10-30% more to do so given the characteristics of the existing roads. It was found in other industries that the frequency of service or volume capacity characteristics of the rail system were superior to the road system. These characteristics were found to be the most important in the study region and were incorporated into a model of transport related development in a frontier region. The first stage of the model covered the development of an interregional link to join the region with its potential markets. This interregional link or path was at first supplied by a road network and is traditionally of poor quality. The second stage coincides with the "opening up" of the region. Resources are developed and some processing of these resources begins. At this stage, a rail network with its lower rates, large capacities and interregional characteristics is the most useful mode. During this stage the region is slowly beginning to develop its urban hierarchy, but is still sparsely settled. The third stage is reached when activities are linked both in a forward and backward direction, to give the region a greater range of products, and in general products with a higher value-to-weight ratio. Because of this and because the urban hierarchy begins to develop, the highway network becomes more competitive. The model therefore presents a way of looking at the changing function of road and rail networks as a frontier region develops. This changing function is based on the characteristics of the transport modes, the production mix of the region and the level of development of the region. / Arts, Faculty of / Geography, Department of / Graduate

Factors affecting the natural revegetation of areas disturbed by airborne emissions were studied at the Anyox smelter on the northern coast of British Columbia. Revegetation of areas where vegetation and soil were removed by industry were studied on mine waste dumps on Vancouver Island, on mine wastes in the West Kootenays, and on abandoned logging roads on Vancouver Island and near Lumby. At Anyox, much of the direct evidence of fume damage was eradicated by a fire in 1942, which occurred eight years after smelting operations ceased. This fire encompassed a five-mile radius surrounding the smelter. Tree-ring analysis on surviving western hemlock trees, extending from the edge of the fire to the head of Alice Arm, showed a strong relationship between the tonnage of ore smelted and the radial increment. Tree growth was initially depressed when smelting began in 1914 and remained low until smelter operations ceased. At this time the growth dramatically increased, but by 1970 the annual radial increment had returned to a slow rate similar to before smelting operations began. Western hemlock was much less susceptible to fume damage than western red cedar. Although total fume kill occurred on western red cedar as far south as the Nass River, north to the head of Hastings Arm and East to the head of Alice Arm, total kill on hemlock took place within a few miles of the smelter. Fume damage was the heaviest near the smelter and near the head of Alice Arm where the topography confined the fumes, rendering them more effective. Within the area affected by the 1942 fire, revegetation was slow near the smelter and was more rapid near the mature vegetation. Seeds which are easily dispersed by light wind, were responsible for the majority of colonizing species many of which were found rarely in the surrounding unburned vegetation. On logging roads and mine waste materials, seed source availability appeared to be the major factor in determining the colonizing species. Light wind-blown seeds were the initial colonizers on coastal logging roads, and adjacent vegetation supplied the seed source for the interior logging roads. The establishment of salal through vegetative means was' observed to occur on coastal logging roads. Species with the ability to fix nitrogen, with the exception of alder, played a minor role in natural revegetation of most areas. Slow revegetation of large-scale disturbances was attributed partly to the lack of adequate seed. The most common cause of slow revegetation in most areas was moisture deficiency. Moisture availability on mine wastes at Cumberland appeared to be determined by slope, aspect, color, shading and mound height. On logging road surfaces, in both Lumby and coastal areas, a reduction in plant growth on steeper slopes was attributed to reduced moisture. Wind exposure was found to be the most important factor governing revegetation of mine wastes in the West Kootenays. Coarse textured material was related to a lower percentage cover of vegetation on the surface of coastal logging roads. Uniformly coarse textured material on the waste dumps in the West Kootenays precluded any significant statistical relationships. Coarse textured materials, nevertheless, had a general inhibitory effect on the rate of revegetation of many of the mine waste dumps. Steep unstable slopes were a major factor which prevented revegetation of West Kootenay mine wastes and on the upslope of road cuts. The scale of disturbance was found to magnify or obscure many of the factors important to successful plant colonization. The chemical composition of waste material, although studied only peripherally, did not appear to be a major factor in determining the revegetation of disturbed areas at the sites studied. Low pH values, which are often taken as a barometer of mine waste toxicity, occurred rarely. In many instances, high pH values may have prevented the successful invasion of acid-loving species. In applied reclamation procedures, it is mandatory that objectives for future land use be incorporated into planning, along with the anticipation of inhibiting factors. If no conditions are left which prevent plant growth, then reclamation will be straightforward and land use goals will be more easily satisfied. / Forestry, Faculty of / Graduate

A literature survey indicated that little was known about the effects of commercial clearcutting on stream and watershed solution chemistry. To investigate these effects, five small watersheds were studied in the University of B.C. Research Forest. Three of the watersheds were equiped with weirs, stream height recorders, and soil-air-water thermographs. Soil pits were dug in the three calibrated watersheds and equiped with surface runoff collectors and hanging water column tension lysimeters. Samples of - precipitation above the forest, throughfall (through forest and slash), surface runoff, forest floor leachate, mineral soil leachate near the bottom of the rooting zone, groundwater, and streamwater - were collected at regular intervals and analyzed for pH, electrical conductivity, alkalinity as bicarbonate, K, Na, Mg, Ca, Fe, Mn, Al, Cl, P, N, S, and Si for periods of up to three years prior to clear-cutting and two years after clearcutting. Streamwater was also analyzed for dissolved oxygen and suspended sediment. Sampling was carried out for periods of up to three years prior to clearcutting and up to two years following clear-cutting. The streams were characterized by high discharges from late autumn until early summer and low discharges from May until October, with almost no contribution from snowmelt runoff. Response to precipitation was fairly rapid and it was hypothesized that stormflow arose mainly from flow of water through macrochannels in the soil. Visual observations and chemical data were consistent with this hypothesis. Evapotranspiration from the gauged watersheds was estimated to be about 85 cm per year by subtracting streamflow outputs from precipitation inputs and 65 cm per year using theoretical methods. The discrepancy between these two values was attributed to an unmeasured leakage of water, particularly from the untreated control watershed which rendered too low the streamflow outputs. There was an increase of 30.8 cm in runoff from one watershed, and 27.6 cm from another during the first six months of the dormant season immediately following clearcutting. During this period runoff from the control watershed was 141.5 cm. Stream temperatures underwent annual cycles with winter minima close to 0°C and summer maxima close to 17°C. Diurnal temperature fluctuations were slight and usually less than a few degrees. Clearcutting caused an increase in both maximum and minimum stream temperatures during the first dormant season following clearcutting. The few measurements which were made of suspended sediment, together with visual observations, indicated that concentrations were usually negligible in the streams. Dissolved oxygen concentrations in streams were usually close to 100% saturation and underwent annual cycles with maximum values in winter and minimum values in late summer and early autumn. Clearcutting had little effect on dissolved oxygen values during the cooler wetter months but caused very pronounced decreases during summer and early autumn. This was attributed to the biological and chemical oxygen demands of decaying slash in the streams. Stream chemistry exhibited little diurnal variation but considerable variation with discharge. Sodium, calcium, magnesium, dissolved silica, and bicarbonate concentrations, and electrical conductivity and pH decreased with increasing discharge, whereas potassium and nitrate concentrations exhibited some increases and some decreases. Chloride and sulphate concentrations were generally not significantly related to discharge. In the undisturbed ecosystems, chemical concentrations, pH, and electrical conductivity throughout the systems were generally highest in late summer and early autumn and lowest in winter and early spring. This was attributed to seasonal cycles of geological and biological activity with accumulation of weathering and decomposition products occurring during dry, warm summers. These were flushed through the system in autumn, with solutions becoming progressively more dilute throughout the winter until the onset of warmer weather. Nitrate concentrations tended to be higher in winter than in summer which was attributed to greater nitrogen uptake by organisms in summer. The most abundant ions in precipitation and throughfall were hydrogen, sulphate, and chloride, while calcium, bicarbonate, and sulphate were dominant in all the other types of water samples. There was a general increase in chemical concentrations to maximum values in forest floor leachate followed by a decrease to minimum values in groundwater, and a slight increase again in streamwater. The lowest pH values were in throughfall (4.0-4.5) followed by a steady increase through the system to maximum values in stream-water (6.5-7.0). Clearcutting increased the pH of water reaching the forest floor and surface runoff but decreased the pH of mineral soil leachate, groundwater, and streamwater. It generally decreased chemical concentrations in water reaching the forest floor and in surface runoff, and, to a lesser extent, in forest floor and mineral soil leachates, but it increased concentrations in groundwater and, to a lesser extent, in streamwater. A most notable increase throughout the system was in the concentration of potassium which was attributed to the relative ease with which potassium is leached from decaying vegetation. Increases in nitrate concentrations were particularly high in groundwater. Streamwater concentrations of potassium, iron, calcium, dissolved oxygen, and probably manganese, were significantly affected by clearcutting; concentrations of all these chemicals increased, except dissolved oxygen which decreased. Slight increases in magnesium, nitrate, sulphate, and chloride concentrations, and electrical conductivity, and decreases in pH and bicarbonate concentrations were also observed. All changes were most noticeable during the low flow periods of late summer and early autumn. There were no obvious effects on sodium, aluminium, ammonium, dissolved silica, and phosphate concentrations. In terms of chemical budgets, there was a general net loss of calcium, sodium, magnesium, potassium, and sulphur from all the watersheds, in their undisturbed state, while nitrogen was accumulated and phosphorus underwent very little change. The chloride balance changed from year to year with losses one year and gains the next. Chemical outputs increased relative to inputs with increasing precipitation so that net losses were greater in winter than in summer. Chemical budgets and stream chemistry at Haney were compared to the results of other studies, particularly one in the nearby Seymour watershed (Zeman, 1973). At Haney, clearcutting significantly increased potassium losses and decreased nitrogen gains in one watershed and significantly increased potassium, sodium, magnesium, and chloride losses in another watershed. From the nutrient viewpoint, it appears that clearcutting has not impaired the mechanisms for nutrient retention in the ecosystems of the type present in the study area. This may not be the case for all ecosystems in coastal B.C., or for other forestry practices, such as slashburning. The study has pointed out the need for further work to quantify the role of macrochannels in soils with respect to hydrologic and chemical behaviour of watersheds. It has also pointed out the danger of extrapolating to larger ecosystems the results of lysimeter studies. Chemical analysis of groundwater may offer a more accurate means of estimating chemical losses from soils than do lysimeters. / Forestry, Faculty of / Graduate

This thesis is an examination of the origins and development of the British Columbia ranching community and livestock industry. The argument is based on the assumption that the settlement of the Southern Interior Plateau stimulated the growth of a peculiar agricultural economy dependent primarily on stock raising, which in turn, played a prominent role in the region's political, economic and social development. The British Columbia ranching frontier was preceded by the practical foundation of agriculture and animal husbandry in the Oregon country under the guidance of the Hudson1s Bay Company and its maturity under the independent American settler. With the discovery of gold in British Columbia, the American ranching frontier extended northward temporarily to fulfill the demands of the mining market and in the process the Interior livestock industry was established. Through the implementation of a pre-emption system and the hesitant introduction of pastoral leases, the colonial administrations slowly came to realize that the settlement of the Interior Plateau depended initially upon the promotion of stock raising. In its first stage of settlement, the isolated ranching frontier did not experience serious competition for site nor did one ethnic, social or economic group control the region's development. With the gradual decline of the mining industry and the frustrations surrounding the transcontinental railway, the new province of British Columbia entered a decade of economic recession. For the Interior ranching community, however, it represented a period of gradual economic expansion and growing influence in the political sphere. Once railway construction was finally commenced in 1880, the ranchers' concentration upon stock raising during the past two decades stimulated a period of unparalleled prosperity and land consolidation for the established Interior ranching population. After 18 8 5 the character of Interior settlement and the livestock industry began to experience the inevitable transitions of a more mobile and industrialized society. While the cattle ranchers, as the largest landowners, maintained a comfortable livelihood, they were visibly alarmed by the formation of large ranching companies and the growing competitive strength of the Alberta ranching frontier. Nevertheless, while the broader problems of the ranching industry now required a more united front, the established ranchers continued to operate on an independent, individualistic basis. Ultimately, this led to tension within the ranching community itself and a declining role in the economy of the province. / Arts, Faculty of / History, Department of / Graduate

This thesis is comprised of four self contained chapters that report the results of a study on the stormflow hydrology of small forested watersheds in the Coast Mountains of southwestern British Columbia. The chapters discuss the general characteristics of the study watersheds and their instrumentation, the generation of stormflows from small forested watersheds, the stormflow (channel-phase) characteristics of one study watershed with steep topography, and the evaluation of initial changes in peak stormflow following logging of another study watershed. Chapter I. The characteristics of the study watersheds with respect to regional climate, physiography, soil hydrologic characteristics and forest cover were evaluated and summarized from available information. Emphasis is placed on the hydrologic characteristics of the watershed soils. The instrumentation of the study watersheds pertinent to the present study is also described. Due to the highly permeable nature of the watershed soils, the physical setting of the study watersheds favor a Rapid response of streamflow to rainstorms. On one study watershed this rapid response characteristic is reinforced by its steep topography and high drainage density. Chapter II. The problem of stormflow generation from small forested watersheds is dealt with by analyzing results from studies completed by the author and other workers in Jamieson Creek watershed and vicinity and by making field examinations in the same study area. A review is made of stormflow generation models, followed by analyses of rainfall intensity, saturated soil hydraulic conductivity and depression storage of the study area. These analyses revealed that overland flow rarely, if ever, occurs on coastal watersheds with hydro-logic environments similar to that of the study area. Instead, rain water takes alternate subsurface pathways through the soil to the stream channel. Observations made by the author in the study area and in other watersheds in this coastal region confirmed the existence of these alternate routes of water flow. Two types of subsurface stormflow pathways have been identified by earlier workers: (1) the matrix of forest floor and mineral soil beneath and (2) channels within or passing through the mineral soil. In the study area most soil channels were developed from dead or decaying roots. After passing through these two types of pathways, subsurface stormflows feed the expanding stream channel system laterally while rainfall is feeding the system from above. Subsurface stormflows are mainly in the form of saturated return flow from the ground and seepage flow through saturated stream banks. The stream channel system expansion during, and contraction after, a storm was measured in a small sub-watershed in the study area. It was found that the rate of stormflow from a watershed was closely related to the rate at which the stream channel expanded in response to the storm. From theestudy it is concluded that the model of subsurface stormflow from a variable source area is more appropriate than the other two models in describing stormflow generation in this coastal region. Chapter III. Stormflow characteristics of Jamieson Creek watershed, a small, steep, and forested watershed in the Coast Mountains of southwestern British Columbia, were evaluated by the analysis of 41 storm hydrographs from 1970-1974. During the study period, the rainfall amount per storm event varied from 5 to 330 mm, with the majority of the storm durations ranging from 20 to 60 hours. On the average, the fraction of storm rainfall that appeared as stormflow was 44 percent, varying from 2.5 to 81 percent. A significant number of major storms produced stormflow that accounted for more than 60 percent of the storm rainfall. Instantaneous peak flows varied considerably with storms, ranging from about 10 to 1,370 -1-2 1 s km and appeared to be mainly affected by the rainfall amount and distribution before the occurrence of the peak flow. Rising time (time to the peak) was short, usually within 30 hours, depending upon the rainfall distribution before the occurrence of the peak flow. Lag time was found to be relatively constant and short, ranging from 5 to 15 hours with an average of 8.5 hours. It is suggested that to derive lag time from characteristics of small watersheds, soil hydrologic properties should also be included with those parameters that are generally used. Stormflow amount was highly correlated with rainfall amount with 92 percent of its variance being accounted for. Antecedent base-flow rate was proposed as an index of watershed soil water storage prior to the storm hydrograph rise. One set of data from Jamieson Creek watershed and four additional data sets from two small steep watersheds in the Coweeta Hydrologic Laboratory were used to assess, through multiple regression analysis, the usefulness of antecedent baseflow rate in improving stormflow-rainfal1 relations. For all data sets, the inclusion of antecedent baseflow as a second independent variable significantly improved the stormflow estimate in comparison to that when rainfall amount was the only independent variable. Recession limbs of storm hydrographs varied with individual storms, depending on the degree of recharge to the watershed storage by the storm and the spatial distribution of such storage over the watershed. The stormflow characteristics of Jamieson Creek watershed reflect the influence of not only climatic conditions but also watershed characteristics: (1) shallow but highly permeable soils, (2) steep watershed slopes and stream channels, and (3) high drariinage density. The stormflow characteristics can be interpreted in terms of the generation of stormflow from a variable source area of the watershed. A comparison of the stormflow characteristics of Jamieson Creek watershed and the adjacent Elbow Creek watershed indicated that stormflow from the former usually has a sharper peak, higher peak flow ratio and steeper recession than stormflow from the latter, but both have very similar rising times. Differences in the streamflow response of the two watersheds could be caused by their differences in some topographical features. However, these differences also suggest that leakage from Elbow Creek, revealed in a preliminary field investigation, may deserve more detailed study. Chapter IV. This chapter provides the first quantitative Canadian information with respect to the impact of logging on peak stormflow. The paired-watershed technique was used to evaluate the initial changes in peak streamflow during storm periods following logging of a small watershed in the U.B.C. Research Forest, near Haney, B.C. Contrary to the majority of similar studies elsewhere, the analysis indicates that significant peak flow changes after logging occurred as follows: (1) an increase in the time to the peak, and (2) a decrease in the magnitude of the peak. The changes can be explained by (1) the degree of ground surface disturbance associated with the logging and (2) the stormflow generation mechanisms of the study area. Visual examination after the logging indicated that ground surface disturbance did not reduce the soil infiltration capacity to the extent that overland flow resulted. Workers in an earlier study speculated that forest floor disturbance could result in closure of some of the entrances to soil channels, thus increasing temporary water storage in the soil matrix. This, they further speculated, would result in reduced subsurface stormflow and, consequently, lower peak flow. The results of the present study tend to support the speculations, that the closure of some soil channel entrances is responsible for lower peak flow after logging. However, this study indicated that peak flow magnitude decreased mainly because of the flattening out of the hydrograph as a result of increased time to the peak (delayed peak rather than earlier hydrograph rise,). It is suggested that a lower rate of stormflow transmission through the soil matrix caused this increased time to the peak and, consequently, lower peak flow magnitude. Implications of this study for better water management are suggested. / Graduate and Postdoctoral Studies / Graduate

This thesis provides an analysis of the drop trailer traffic moving between the B.C. Mainland and Vancouver Island. Drop trailers are semi trailers which are literally dropped at the ferry terminal to be transported across the Strait of Georgia without the accompaniment of the power unit and driver. This specialized service is provided only by the British Columbia Coastal Steamship Service, a subsidiary of CP. Rail. One objective of the thesis is to analyze the economics of shipping via drop trailer as opposed to a live unit, or one that includes the driver and tractor unit such as is provided by the B.C. Ferries. A second objective is to determine the size and importance of the market, and to forecast future requirements. A third objective is to analyze the physical facilities available to determine their capacity and possibilities for expansion. The B.C.C.S.S. facility in downtown Vancouver is under pressure from various groups to relocate to a more suitable location. Thus a final objective is an analysis of the benefits and costs of relocating the B.C.C.S.S. terminal to the north Richmond area. Since the drop trailer industry is very specialized, and captive to the B.C.C.S.S., very little information is published or available concerning it. Thus the author has had to rely primarily on discussions with all the parties involved, namely the B.C.C.S.S., City of Vancouver, and numerous carriers. One of the by-products of the thesis is a body of information and data pertaining to the drop trailer industry, that can be used for future research in related topics. The analysis of the economics of shipping via drop trailer shows a substantial savings potential, even though the actual ferry cost is greater. The savings are generated by the elimination of idle driver and tractor time. This saving was estimated at $49.20 per one way trip. During the past decade the volume of drop trailer traffic has been increasing steadily even though railcar traffic has been on the decline. This increase is causing the B.C.C.S.S. to approach the capacity of the present system. Political and physical pressures have raised the issue of relocating the terminal A benefit-cost analysis of a particular alternative, a partial relocation to the north Richmond area shows there can be substantial benefits for carrier as well as the B.C.C.S.S. / Business, Sauder School of / Graduate

The landscapes of British Columbia, prominently modified by glaciation, present many large and varied wetlands. These wetlands have not been well delineated nor classified although they are being rapidly modified for residential, agricultural and industrial developments. Some federal and provincial agencies are currently undertaking inventory and classification based largely on soil profile characteristics. To complement these efforts, particularly for management purposes, this study was undertaken in which predominantly plant-mediated processes were examined. The investigations were limited to the maritime marshes of south western British Columbia with study sites located in the Pitt, Brunswick and Iona marshes. Estimates of productivity were obtained from single and sequential harvesting of the aerial vegetation. Peak standing crops varied between species and between sites. Species differences were attributed to plant characteristics such as photosynthetic canopy development and shoot configuration. Peak standing crops were also related to environmental variables such as climate, water regime, salinity and substrate nutrient status. Data from sequential harvesting revealed that most emergents experienced a rapid growth in the spring and early summer declining with the onset of cold weather in the fall. Time of peak production differed markedly between species depending on presence or absence of overwintered photosynthetic shoots, time of shoot emergence and seasonal shoot mortality rates. Studies of belowground organs showed that roots and rhizomes may comprise up to 85 percent of the total phytomass of emergent vegetation emphasizing the importance of this fraction in wetland functions and processes. The main routes of disposition of the emergents were identified as the grazing route, accumulation route and the detrital route. Grazing was relatively unimportant in the marshes. Any grazing of the living vegetation was carried out largely by gastropods, earthworms, insects and resident and migrant waterfowl. Minimal grazing of the marsh vegetation appeared to be related to unfavourable wetland conditions, high levels of structural constituents and low levels of nitrogen in the plants. Quality of the vegetation declined sharply with age. Low ash levels and high phenolic content were also implicated in the minimal grazing of the Pitt marsh vegetation. Total energy content appeared to be unimportant in this regard. Organic matter accumulation was a distinct feature of the marshes studied. There was more organic matter accumulation in the Pitt than in the Brunswick marsh. Accumulation also seemed to be more uniform over large areas in the Pitt marsh than in the tidal marshes. Data from old growth samples indicated that a large portion of the phytomass produced in the marshes enters the detrital pathway via decomposition. Factors affecting decomposition rates were discerned largely from litter bag trials and in vitro decomposition studies. Fragmentation of litter by physical forces generally preceded biological degradation. Such comminution was more marked in the Fraser delta marshes where tidal and freshet activities are predominant. Temperature was a significant factor affecting disappearance rates. The rates were generally lower in the "cooler" Pitt marsh than in the "warmer" Brunswick marsh. Low soil temperatures together with low oxygen tensions were responsible for the relatively low decomposition rates in buried litter samples. Decomposition rates also reflected the chemical composition of the emergent vegetation. Less fibrous species such as Carex lyngbyei were more readily degraded than more fibrous species such as Carex sitchensis. Leaching of readily degradable plant materials occurred in significant quantities both in living and dead vegetation. Leaching losses in living shoots averaged 64 mg/g leaf dry matter in 4 days. Variations in stomatal number, shape and distribution were implicated in the possible mechanisms controlling leaching losses in living emergent vegetation. In dead shoots, dry weight losses of up to 50 percent were recorded over a four month period. Such losses were attributed mainly to leaching. High initial losses in the litter bag and in vitro decomposition trials were also suggestive of leaching. / Land and Food Systems, Faculty of / Graduate

The Poplar copper-molybdenum porphyry deposit, located 270 km west of Prince George, is centered in a late Upper Cretaceous differentiated calc-alkaline stock, which intruded Lower and Upper Cretaceous sedimentary rocks. The stock is capped by late Upper Cretaceous volcanic flow rocks. The lower Cretaceous Skeena Group consists of intermediate tuff, siltstone, and interbedded sandstone, which steeply dip to the south. This unit is unconformably overlain by a moderately sorted polylithic pebble conglomerate belonging to the Upper Cretaceous Kasalka Group. The Poplar Stock, which hosts mineralization, includes a border phase of hornblende quartz monzodiorite porphyry which grades in to a central biotite quartz monzonite porphyry. The stock is intruded by several post-ore dyke units, which include porphyritic dacite, porphyritic rhyolite, felsite, and andesite. Ootsa Lake porphyritic volcanic flow rocks overly the deposit, and are dacite in composition. Pre-ore, and post-ore rock units have been K-Ar dated, and are within analytical error of each other, having a mean age of 74.8 ±2.6 Ma. The deposit is covered extensively with glacial till and alluvial sediments. Therefore the majority of geologic information was obtained from logging the drill core from 34 diamond drill holes, twelve of which were logged in detail using a computer compatible logging format. Information logged in this manner was used in statistical studies , and for producing computer generated graphic logs and plots of various geologic parameters, along two cross-sections through the deposit. Alteration zoning at the Poplar porphyry consists of a 600 m by 500 m potassic alteration annulus which surrounds a 300 m by 150 m argillic alteration core. These are enclosed by 750 m wide phyllic alteration zone, which is itself bordered by a low intensity propylitic alteration zone. Phyllic alteration is defined by the occurence of sericite, and is the most abundant type of alteration present. Potassic alteration, recognized by the occurence cf secondary K-feldspar and/or secondary biotite, is most closely associated with chalcopyrite and molybdenite. At least two episodes of alteration are recognized at the Poplar porphyry. The first was contemporaneous with mineralization, following intrusion and crystallization of the Poplar Stock. This episode consisted of potassic alteration in the center of the deposit, which surrounded a 'low grade1 core, and graded out to phyllic and propylitic alteration facies at the periphery. The second alteration event took place after the intrusion of the post-ore dykes and consisted mainly of hydrolytic alteration of pre-existing alteration zones which were adjacent to more permeable centers, such as faults, contacts, and highly jointed areas. This alteration event is responsible for the anomalous central argillic zone, and the alteration of dykes, in addition to probably intensifying and widening the phyllic alteration halo surrounding the deposit. Chalcopyrite and molybdenite were deposited in the potassic zone at approximately 375° C and less than 250 bars, with relatively low oxygen, and relatively high sulfer, activities and moderate pH. As the potassic alteration zone was invaded by more acidic solutions feldspars were altered sericite and clay, and chalcopyrite was destroyed to form pyrite and hematite. Copper was removed from the system. Statistical studies include univariant one-way and two-way correlation matrices, and multivariant regression analysis. Statistical correlations generally support empirical correlations made in the field. These include positive correlations between various potassic alteration facies minerals, and these minerals and chalcopyrite and molybdenite. Multivariant regression analysis was used to determine which alteration minerals were best suited for indicating chalcopyrite and molybdenite. These minerals are quartz, biotite, magnetite, sericite, K-feldspar, and pyrite. Large error limits and poor correlation statistics in the results from these studies are attributed to deviations from normal distributions for all minerals. A possible cause of this may have been the multistage alteration events that the deposit has undergone. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate