This thesis describes the biogeoclimatic zones on the southwestern British Columbia mainland and gives a detailed analysis of the vegetation-environmental patterns within the Coastal western hemlock zone. Ecosystem classifications are proposed utilizing coordination techniques and stratification. The major underlying causes of variations in the floristic structure among individual ecosystems are identified by four environmental gradients: regional climate, parent material, local climate (exposure), and soil-moisture regime. The orographic influence of Vancouver Island and the Coast Mountains results in a regional climatic gradient from low to high elevations. Natural segments of this gradient, recognized on the basis of zonal (climatic climax) vegetation and mesic soils, constitute the biogeoclimatic zones and subzones. Land types are separated from within the Coastal western hemlock zone on the basis of parent materials. The rock outcrop land type includes a mosaic of peaks, knolls, and crevices characterized by a coincident pattern of the vegetation types. All glacial drift deposits, except those of the swampy habitats, belong to the glacial drift land type. Maximum floristic variations in the glacial drift land type occur along a soil-moisture gradient. A lesser variation in the floristic structure is attributed to a local climatic gradient from cool to warm exposure. These gradients signify different sets of vegetation types in the different subzones of the Coastal western hemlock zone. The spring-water swamp land type includes waterlogged mineral soils and waterlogged woody peats in the vicinity of spring lines. The vegetation of the spring-water swamps has remarkable uniformity throughout both subzones. Narrow valley-like depressions with permanent or semipermanent streamlets and intermittent overflow water constitute the ravine alluvial land type. The vegetation of the ravines shows little variation among the two subzones. The flood-plain communities of the Squamish alluvial plain land type reflect the influence of overflow water and post-flood drainage. The basic unit of classification used is the ecosystem type, a segment in a simple vegetation-environmental gradient. A vegetation-environmental gradient is simple if it consists of a single set of vegetation types along an environmental gradient. Ecosystem type mapping involved approximately 85 acres in the southwestern part of the University of British Columbia Research Forest; a map is enclosed (in the thesis). / Science, Faculty of / Botany, Department of / Graduate

The vegetation of the Subalpine Mountain Hemlock Zone was studied on 130 sample plots with analytic and synthetic methods of the Zürich-Montpellier school of phytosociology. This thesis describes 14 plant associations, predominantly of vascular plants, from two altitudinal subzones of the Subalpine Zone. Published radiosonde temperature data, in combination with thermograph data from Mount Seymour, were used to characterize the climate of the zone. In winter, which is the season of maximum precipitation, the freezing isotherm most frequently occurs at altitudes near the lower limit of mountain hemlock. A climatic result is the sharp increase in snow accumulation and duration near the lower limit of this species; an ecological result is the relatively sharp boundary between the Subalpine Mountain Hemlock Zone and the Coastal Western Hemlock Zone. Thus, the lower limit of the zone is indicated by the presence of mountain hemlock as a component of the forests and the upper limit is marked by the altitudinal "tree limit" of mountain hemlock. The zonal limits were placed at 3000 and 5000 feet in the Seymour - Grouse - Hollyburn - Cathedral Mountain area near the Strait of Georgia, and at 3700 and 5500 feet in the Paul Ridge - Diamond Head portion of Garibaldi Park. The lowest 600 to 800 feet of the zone are covered with continuous forest of mountain hemlock, amabilis fir, yellow cedar and western hemlock. This continuous forest is designated as the lower subzone. The upper boundaries of the zone, in contrast to the lower, are irregular as a result of topographic influences on snow duration. Snow accumulation increases with altitude so that near the tree limit mountain hemlock can grow only on prominences or ridges where snow duration is less. Most early stages of vegetation appear to develop towards the Phyllodoce - Cassiope association in the upper subzone. At altitudes of approximately 5000 feet and over (Alpine Zone), this association occupies mesic habitats where the relief is flat or convex and without seepage. In contrast, this same association occupies concave topographic positions, with temporary seepage, in the Subalpine Zone. Snow duration is approximately the same on this association in both bioclimatic zones. However, because of its occurrence on two distinct topographies it is chionophobous in the Alpine Zone but moderately chionophilous in the Subalpine Zone, when considered in relation to adjacent associations. The Vaccinium membranaceum - Rhododendron association is the most successionally advanced in the upper subzone. Near its lower limit, this association occupies mesic habitats but at its upper limit in the Alpine Zone it becomes a 'topographic climax' restricted to warmer exposures or to ridges between areas of Phyllodoce and Cassiope. In the lower subzone, the Vaccinium alaskaense association is successionally most advanced. Even if a distinct climatic "climax" association is recognized for the lower subzone, there are no tree species limited specifically to this altitudinal level. Both subzones are unified by the same tree species into one Subalpine Zone. Within this altitudinal belt most zonal features of the vegetation are related to the intensity, quantity and duration of snow. / Science, Faculty of / Botany, Department of / Graduate

An attempt was made to find the relations between the occurrence, abundance, dominance, constancy and vigour of corticolous and lignicolous cryptogams in some forest associations of Douglas-fir forest on Vancouver Island. It has been found that corticolous and lignicolous plant sociations do indicate the particular stratum of the ecoclimate of forest associations. Bryophytes (studied by Krajina) and lichens growing as corticolous and lignicolous plants correspond to the limiting climatological factors which occur in different ecoclimates. The ecoclimate of the forest associations forms one or two or several climatic strata, which are expressed by the corresponding corticolous socia tions on the same tree species. These ecologically differentiated strata develop a zonation phytosociologically defined. Corticolous and lignicolous sociations forming part of the ecosystem of the forest association furnish further characteristics for their differentiation. Its practical use is obvious, especially in winter when the ground vegetation is covered by snow. / Science, Faculty of / Botany, Department of / Graduate

This thesis attempts to devise a classification of ecosystematic units which reflect the rates, patterns and environmental determinants of plant community formation on recently deglaciated terrain. A series of three glacial valleys located in Garibaldi Park, approximately 60 miles east of Vancouver, British Columbia, and lying between elevations of 4800 and 5000 feet above sea level, were studied. The valleys lie in a transition area between coastal and interior biogeoclimatic zones and thus derive their pioneer flora from elements of the Coastal Subalpine Mountain Hemlock Zone, the Coastal Alpine Zone and the Interior Engelmann Spruce - Subalpine Fir Zone. Climate, geology and soil development in the three valleys were studied in order to provide an understanding of the macroenvironmental conditions under which the vegetations was developing. Temperature, humidity, and rainfall were measured for three field seasons (1965 through 1967) to determine the degree of climatic homogeneity of the study area, to examine the effect of glacial proximity on microclimate within the valleys and to establish a gross moisture balance for the growing season. Snow duration was noted for all vegetated sites. A brief description of the parent rocks contributing to the glacial till in the valleys is provided. The chronology of ice retreat in each valley is documented by growth ring analysis of trees established on differently aged surfaces and by reference to studies of synchronous glacial movements in western North America. Soil development was studied by chemical analysis of soil samples taken from pits associated with various plant communities. Changes in total nitrogen, organic matter, C:N ratio, cation exchange capacity and macronutrient cations have been noted with advancing substrate age and altered vegetation cover. Vegetation was sampled using 16 m² sample plots in which vegetation stratification, floristic composition and species abundance-dominance, sociability and vigour were estimated. A classification of ecosystematic units was then synthesized by grouping samples on the basis of overall floristic similarity, dominance by a characteristic combination of species and uniformity of ecotope. The phytosociological synthesis was compared with a cluster analysis of the sample plots using species presence and cover, a method which yielded a similar but not identical set of groups to the ecosystem units. A total of twelve ecosystem units was delimited representing a number of pathways in plant succession and ranging in age from 40 - 150 years since ice retreat. Detailed ecological relationships with the ecosystematic units have been determined from microenvironmental measurements, soil nutrient analyses, sap pressure studies, and autecological analyses associated with the original sample plots. Variations in soil moisture content, surface temperature extremes and snow duration were recorded and correlated with plant community development. Soil nutrient availability was determined for soil samples from pits within sample plots representing the various ecosystematic units. Apparatus and field methods were developed to monitor the diurnal variation of internal moisture stress for a number of successionally important species. Sap pressure, negative tension on the water stream in the xylem, was correlated with net radiation to the plants and atmospheric moisture deficits. A statistical comparison of sap pressure regimes and distribution of four Salix shows that their distribution into different ecosystem types is predictable from their mean sap pressures. For all species of significant coverage an autecological summary has been prepared from plot analysis records showing their modalities to hygrotope, snow duration and age of substrate since ice retreat. Climate, geology, substrate chronology, soil development, microenvironment, autecological relationships, and phytosociological units with their successional roles have been combined to provide a synecological summary for each ecosystematic unit. Maps of the glacial valleys are presented which show the actual distribution of individual communities within each unit. / Science, Faculty of / Botany, Department of / Graduate

Concommittant with an increasing trend towards the ecological classification of forest land in British Columbia is the need for more detailed vegetation inventories and larger mapping scales. Although existing classification schemes (biogeoclimatic, provincial biophysical and habitat type classification) usually present a useful initial stratification of broad zonal vegetation patterns, they seldom provide, or were intended to provide a classification suitable for detailed vegetation inventory and mapping in a particular study area. In most instances, primary vegetation data must be collected and classified at a level of detail compatible with the scale of mapping and the variability of the vegetation landscape. Limited access and steep mountainous terrain are additional problems contributing to the acquisition, classification, interpretation and mapping of vegetation at large scales. Dissimilarity Analysis is a numerical classification analysis programmed and studied by the provincial government as a means to stratify large volumes of vegetation data in a relatively objective and efficient manner. As a divisive-polythetic classification strategy it demonstrates several advantages over other numerical analyses. Although it is now used as a routine analysis by the provincial biophysical survey, it has not yet been thoroughly evaluated or formally presented with regard to its suitability for vegetation classification and mapping on an operational basis. This study investigated four related questions: a. What methods can be employed for detailed vegetation mapping (scale 1:15,840) in mountainous terrain with limited access? b. What is the value of Dissimilarity Analysis for the classification of vegetation in primary survey? c. What is the predictive capability of the pretyping (prestratification) approach developed for vegetation mapping? d. What is the reliability of the vegetation maps. The study was divided into two separate but related investigations: the operational classification and mapping of vegetation in two small mountainous watersheds and a detailed systematic sampling study of two representative areas within one of the watersheds to assess the vegetation mapping procedure and map reliability. A detailed vegetation mapping procedure was developed which utilized permanent physiographic landscape features directly observable or inferred from black and white stereo aerial photographs (scale 1:15,840), macro and meso physiognomic vegetation features, a simple concept relating the above features to the available moisture for vegetation, and information about existing vegetation (e.g. forest cover maps; concepts and maps of vegetation zonation). Dissimilarity Analysis was found to be an objective and efficient method of vegetation stratification by reducing personal bias and ensuring an optimum and consistent utilization of the available information in the data set. It was felt to be an appropriate technique for stratifying primary vegetation data since it maximizes differences between groups, defines limits to classes and facilitates the formation of a hierarchical identification procedure. It was concluded that the vegetation pretyping approach developed for operational mapping provided a methodical, preliminary stratification of the landscape upon which improved mapping criteria could be added to better predict present vegetation condition. A quantitative assessment of map reliability in two representative areas of one of the watersheds resulted in a value of 79% relative to an independent chance of agreement of 6.2% and an optimum chance of agreement of 29%. It was felt that these values were representative of the map reliability in the remainder of the watershed. / Forestry, Faculty of / Graduate

The Sphagnum bogs of the Tofino-Ucluelet area of the western coast of Vancouver Island were studied from vegetational, edaphic, and historical aspects. An integrated approach to these three aspects was attempted in order to give in a relatively limited time as complete a picture as possible of the bog ecosystem. The bog vegetation was studied on 110 sample plots using analytical and synthetic methods of the Zurich-Montpellier school of phytosociology. Ten different vegetation types were described and characterized, nine belonging to the bog ecosystem and one to the surrounding scrub forest. The nine bog vegetation types consist of five distinct associations and one association composed of five variants. The vegetation types studied are summarized below, in order of increasing floristic complexity. Low moor bog associations: 1. Caricetura pluriflorae (Carex plurlflora association) 2. Scirpeto-Sphagnetum mendoclnl (Sclrpus caespitosus - Sphagnum mendocinum association) 3. Oxycocceto-Sphagnetum papillosi (Oxycoccus quadripetalus - Sphagnum papillosum association) High moor bog association: 4. Ledeto-Sphagnetum caplllacei (Ledum groenlandicum - Sphagnum capillaceum association) Peripheral bog associations: (Bog-forest transition) 5. Pineto-Sphagnetum capillacei (Pinus contorta - Sphagnum capillaceum association) a. Pineto-Sphagnetum capillacei sphagnosum papillosi (Pinus contorta hummock variant) b. Pineto-Sphagnetum capillacei myricosum galis (Myrica gale variant) c. Pineto-Sphagnetum capillacei chamaecyparosum nootkatensis (Chamaecyparis nootkatensis variant) Secondary succession variants established after fire: d. Pineto-Sphagnetum capillacei vacciniosum vitis-idaeae (Vaccinium vltis-idaea variant) e. Pineto-Sphagnetum capillacei vacciniosum parvifolii (Vaccinium parvifollum variant) Scrub forest association surrounding bogs: 6. Pineto-Chamaecypareto-Sphagnetum recurvi (Pinus contorta - Chamaecyparis nootkatensis - Sphagnum fecurvum association) (Bog forest) Edaphic considerations were limited to the analysis of soils from representative sample plots of each association and variant. Soils were analyzed for available cations, including Ca⁺⁺, Mg⁺⁺, Na⁺, K⁺, adsorbed phosphate, total nitrogen, cation exchange capacity, percent base saturation pH, and soil moisture. The results of the soil analyses were wherever possible correlated with trends in the development of plant associations. Climatic factors were regarded as constant over so limited an area as the one under study. Historical considerations included a pollen analysis from a representative core in the center of the major study bog, and a radiocarbon dating to determine the age of a representative bog. The results of the pollen analysis appeared to confirm previous ideas that the bog did not develop from a lake, but rather it developed from a wet seepage forest habitat. The radiocarbon dating indicated the age of the bog at only 390± 90 years B.P., thus explaining partially the apparent very juvenile phase of the bogs of the area. The general hypothesis is suggested that the distribution of the bog plant associations is primarily dependent upon a complex of environmental factors that are dependent upon topography. / Science, Faculty of / Botany, Department of / Graduate

In this study, three cores obtained from Burns Bog just south of the Fraser River in Delta, British Columbia, were analyzed palynologically. The paleoecology of the bog was reconstructed from the results of these analyses, together with data from vegetation studies of the bog, pollen rain and surface pollen spectrum investigations of selected wetland environments, as well as pollen tetrad and pollen productivity studies of bog ericads. The vegetation of Burns Bog was sampled by estimating species cover in selectively placed 100 m² quadrats. These field data were used in combination with an air photographic mosaic to map the eight vegetation types of the area. The palynomorph "fingerprints" of selected wetland environments, determined from pollen rain and surface pollen spectrum studies, were used to recognize analogous phases recorded in cores. Tetrad diameter and pollen productivity data for bog ericads assisted in recognizing ecologically significant ericad species that distinguished wet and dry raised bog phases. The study shows that Burns Bog has developed on Fraser River deltaic deposits which appeared above sea level just after 5,000 years BP. The seemingly synchronous emergence of the three core sites and a locality in adjacent Boundary Bay indicate a possible relative sea level decrease at this time. The silty emergent sediments are characterized by high percentages of Pinus and Picea pollen deposited by river water, and Cyperaceae pollen from local Scirpus and Carex stands. Following this emergence, sedges colonized the area, forming a sedge peat containing abundant Cyperaceae pollen. At the western end of the bog, a salt marsh developed (4,125 ± 110 BP) in response to a marine advance. This was possibly caused by a shut-off of fresh-brackish water from the Fraser River when the delta reached Point Roberts. In the eastern section of the bog, at the foot of Panorama Ridge, the sedge phase was only transient. A Myrica-Spiraea-Lysichitum swamp developed, remaining until very recently. After the sedge phase in the central part of the bog, Myrica and Spiraea thickets appeared; these were subsequently replaced by Sphagnum bog at 2,925 ± 85 years BP. In the western end of the bog, sedges were replaced by heaths, predominantly Ledum. At the foot of Panorama Ridge, Sphagnum arrived very recently. Pines seem to have invaded all sites at the 2.00 m level. The AP pollen spectrum shows that the regional upland vegetation remained unchanged throughout the history of Burns Bog until settlers cleared the forests. On the delta, however, fluctuations in alder pollen were probably associated with alder colonization of levees and swamps near the channels. Fire has played an important role in bog ecology. Natural Sphagnum accumulation processes are modified because fire destroys the vegetation of slightly higher, dry sites. Unburned wet depressions then become centers of peat accumulation. These sites eventually rise above the surrounding burned areas, which are converted to depressions. A model for raised bog development is proposed for the Fraser Lowland. The prograding delta-front is colonized by emergent aquatics growing on silts. This phase is followed by the advent of a sedge swamp perhaps containing some wetland grasses. Eventually, shrubs such as Myrica and Spiraea begin to appear, accompanied in the later stages by Ledum groenlandicum. Increased acidity of the substrate due to peat accumulation promotes Sphagnum, which eventually takes over and results in the establishment of raised bog conditions. This study, the first detailed outline of raised bog development in western North America, provides a framework for further investigations of bogs in the area. / Science, Faculty of / Botany, Department of / Graduate

Botanical exploration in northern British Columbia has lagged behind that of adjacent Alaska and the Yukon Territories. This is particularly true of alpine and sub-alpine areas. For the most part, limited accessibility has restricted plant collecting to within a short distance of the few available roadways. During the course of the present study, botanical field work was conducted in an alpine, sub-alpine area in the Three Sisters Range of the Cassiar Mountains (northwestern British Columbia). Over 1000 vascular plant collections were idenified from the study area. A total of 239 Taxa were recognized representing 116 genera and 44 families. Taxonomic keys to the local flora and an annotated species list are provided. The annotated species list includes : habitat information for each taxon, a list of associated species and, where applicable, a discussion of noteworthy features of the taxon in question. Approximately 13% of the flora examined is listed as rare in British Columbia in Straley et al. (1985). Virtually all of northern British Columbia was overridden by the Cordilleran Ice Sheet during the last major Wisconsin advance (approximately 22,000-15,000 yrs. b.p.). Potential Refugia from which taxa now present in the study area may have migrated post-glacially are discussed. Worldwide distributions of each taxon were examined and seven phytogeographic elements are recognized in the flora. / Science, Faculty of / Botany, Department of / Graduate

Discrimination of different tree crowns based on their 3D shapes is essential for a wide range of forestry applications, and, due to its complexity, is a significant challenge. This study presents a modified 3D shape descriptor for the perception of different tree crown shapes in discrete-return LiDAR point clouds. The proposed methodology comprises of five main components, including definition of a local coordinate system, learning salient points, generation of simulated LiDAR point clouds with geometrical shapes, shape signature generation (from simulated LiDAR points as reference shape signature and actual LiDAR point clouds as evaluated shape signature), and finally, similarity assessment of shape signatures in order to extract the shape of a real tree. The first component represents a proposed strategy to define a local coordinate system relating to each tree to normalize 3D point clouds. In the second component, a learning approach is used to categorize all 3D point clouds into two ranks to identify interesting or salient points on each tree. The third component discusses generation of simulated LiDAR point clouds for two geometrical shapes, including a hemisphere and a half-ellipsoid. Then, the operator extracts 3D LiDAR point clouds of actual trees, either deciduous or evergreen. In the fourth component, a longitude-latitude transformation is applied to simulated and actual LiDAR point clouds to generate 3D shape signatures of tree crowns. A critical step is transformation of LiDAR points from their exact positions to their longitude and latitude positions using the longitude-latitude transformation, which is different from the geographic longitude and latitude coordinates, and labeled by their pre-assigned ranks. Then, natural neighbor interpolation converts the point maps to raster datasets. The generated shape signatures from simulated and actual LiDAR points are called reference and evaluated shape signatures, respectively. Lastly, the fifth component determines the similarity between evaluated and reference shape signatures to extract the shape of each examined tree. The entire process is automated by ArcGIS toolboxes through Python programming for further evaluation using more tree crowns in different study areas. Results from LiDAR points captured for 43 trees in the City of Surrey, British Columbia (Canada) suggest that the modified shape descriptor is a promising method for separating different shapes of tree crowns using LiDAR point cloud data. Experimental results also indicate that the modified longitude-latitude shape descriptor fulfills all desired properties of a suitable shape descriptor proposed in computer science along with leaf-off, leaf-on invariance, which makes this process autonomous from the acquisition date of LiDAR data. In summary, the modified longitude-latitude shape descriptor is a promising method for discriminating different shapes of tree crowns using LiDAR point cloud data.