Thesis (Ph. D.)--Institute of Paper Chemistry, 1982. / Includes bibliographical references (p. 104-108).

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The superior growth of Grand fir (Abies grandis) compared to Douglas-fir (Pseudostuga menziesii) on suitable coastal sites has previously been recognized on the basis of qualitative observations with little empirical evidence. For example, D.E. McMullan (1977, pers. comm.) reported 18% higher volume for a grand fir tree of the same height and age as a 108-year old Douglas-fir plus tree (No. 622) This study was undertaken by Bernardy (1988) to examine possible differences in the growth of grand fir and Douglas-fir growing in a mixed 40-year-old plantation of unknown origin. Trends in height, diameter and annual volume increment between the two species over time were examined. Expected growth performance (i.e. volume and form) of each species was inferred from trends identified at time of sampling.

Regeneration of Douglas-fir following harvesting has proven difficult on many sites in British Columbia. As a result, alternative nursery practices are being explored to improve seedling growth. Using two experiments I aimed to identify an improved nutritional program for Douglas-fir seedlings. The objective of the first experiment was to identify the optimum nitrogen (N) source ratio for Douglas-fir between two inorganic sources of N, ammonium (NH4+) and nitrate (NO3-). Seedlings were grown in controlled environments in aeroponic culture with solutions containing 0:100, 20:80, 40:60, 60:40, 80:20 or 100:0 NH4+:NO3- ratios. Growth and nutrient allocation was observed for 45 days. Different NH4+ and NO3-ratios resulted in significant differences in growth and nutrient allocation. Seedlings grown in solutions containing abundant and relatively equal portions of NH4+ and NO3- were characterized by the greatest relative growth rates, greatest biomass and stable internal nitrogen concentrations. Seedlings grown in solutions containing high NH4+ (80:20 and 100:0 NHS+:NO3-) concentrations were characterized by lower relative growth rates, less biomass, lower internal nutrient concentrations and lower rates of photosynthesis and root respiration compared to seedlings with less NH4+ (20:80, 40:60 and 60:40 NH4+:NO3-). Seedlings appeared to take up a greater proportion of NH4+ than NO3- from solution. The objective of the second experiment was to examine the implications of two nursery fertilization regimes for growth and nutrient dynamics. Seedlings were grown in a nursery with nutrients added at a constant rate (conventional fertilization) or at an exponentially increasing rate of 2% day-1 (exponential nutrient loading). At the time of planting, half of the conventionally fertilized seedlings were planted with slow release fertilizer packets. Growth and nutrient allocation was observed for two years following planting. In the field experiment, although exponential nutrient loading applied 25% more N in the nursery compared to the conventional regime, no benefits in growth or nutrient allocation were found. Two years after planting, there were no significant differences in height, root collar diameter or total dry mass between seedlings grown under the different nursery fertilizer regimes. In contrast, seedlings planted with additional fertilizer consistently outperformed seedlings grown with exponential nutrient loading, with greater height, root collar diameter and dry mass. Two growing seasons after planting there were no significant differences among treatments in whole-plant N concentrations.

Virtually all current estimates of the maximum carboxylation rate (V.) of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and the maximum electron transport rate (.Imax) for C3 species used to parameterise Land Surface Models (LSMs) implicitly assume an infinite CO2 transfer conductance from intercellular spaces to the sites of carboxylation (gi). And yet, most measurements in perennial plant species or in ageing or stressed leaves show that gi imposes a significant limitation on photosynthesis. In this study, I demonstrate that many current parameterisations of the photosynthesis model of Farquhar, von Caemmerer & Berry (1980) based on the leaf intercellular CO, concentration (Ci) are incorrect for leaves where gi limits photosynthesis. I show how conventional A-C, curve (net CO2 assimilation rate of a leaf - An - as a function of Ci) fitting methods which rely on a rectangular hyperbola model under the assumption of infinite gi can significantly underestimate Vcmax for such leaves. Alternative V., parameterisations of the conventional method based on a single, apparent Michaelis-Menten constant for CO, evaluated at C; and used for all C3 plants are also found to be inaccurate since the relationship between Vcmax and g; is not conserved among species. To address this problem, I present an alternative curve fitting method that accounts for gi through a non-rectangular hyperbola version of the model of Farquhar et al. (1980). Current estimates of a central Farqhuar et al. (1980) model parameter, Kc(1+O/K0) (effective Michaelis-Menten constant for CO2), vary 4-fold, making it very difficult to justify any single value for the parameterisation of large scale, pan-species LSM studies. Following on previous work published over two decades ago, I demonstrate that the current range of Kc(1+O/K0) values chosen for LSMs is partly an artefact of many inaccurate in vitro determinations, and results in widely different estimates of An for given Vcmac values. Once corrected, the average Kc(1 +O/Ko) value determined in vitro for C, plants is essentially identical to the two in vivo values published to date, but considerable variation within the data set remains due to the poor accuracy of the in vitro determinations. The new A-Ci curve fitting method elaborated in this study suggests new ways of obtaining in vivo estimates of Rubisco's kinetic constants, as I demonstrate through a well-documented example. The CO, transfer conductance was originally considered to be a constitutional property of a leaf related to its internal anatomy. This study provides the first estimates of gi in a coniferous species and examines variation in gi through time and space in relation to anatomical and physiological traits. Gas exchange measurements and subsequent novel A-Ci curve analyses, as well as stable carbon isotope, nitrogen (N), protein, and pigment analyses, were made on upper and lower canopy, current- to 4-year-old needles of 50-year-old Pseudotsuga menziesii trees. During the first growing season, needle thickness and leaf mass per area decreased by 30% from the top to bottom of the canopy. These anatomical changes were accompanied by modest variation in area-based estimates of g , but no causal link could be established between anatomical traits and mass-based estimates of gi, whether in current- year or older foliage. Both gi and the stomata] conductance of leaves were closely coupled to Vcmax, Jmax, and An with all variables decreasing with increasing leaf age. The N content of leaves, as well as the amount of Rubisco and other proteins, increased during the first three growing seasons, then stabilised afterwards. Thus, the age-related photosynthetic nitrogen use efficiency decline of leaves was not a consequence of decreased allocation of nitrogen towards Rubisco and other proteins. Rather, loss of photosynthetic capacity was the result of the decreased activation state of Rubisco and proportional down-regulation of electron transport towards the photosynthetic carbon reduction and photorespiratory cycles in response to a reduction of CO, supply to the chloroplasts' stroma.

The submaritime zone of British Columbia experiences summer drought and spring and fall frosts which cause high mortality of seedlings planted for reforestation. Seedlings of half-sib Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) families were studied at 3 test sites in the coast mountains of British Columbia, and in a complementary pot trial on southern Vancouver Island from 2007-2008, with the aim of studying physiological traits related to cold and drought hardiness. These families originated from British Columbia's submaritime zone, and had a range of breeding values. This allowed for comparison of growth and stress resistance traits among progeny with expected differences in performance. In the field trial, spring and fall cold hardiness were assessed using chlorophyll fluorescence after controlled freezing. Growth and mortality data, shoot water potential and carbon isotope discrimination were recorded as measures of drought stress and water use efficiency. In the pot trial, a subset of families was grown under 3 drought levels to study drought hardiness characteristics. Growth, biomass allocation, date of vegetative bud burst, gas exchange, shoot water potential, and chlorophyll fluorescence were measured. Means comparisons between families, treatments and study sites were performed, narrow-sense heritabilities were calculated, and physiological traits were compared using correlation analyses. Family, field site and drought treatment had significant effects on many physiological parameters. Wild stand families tended to have greater field survival and fall cold hardiness than seed orchard families. Field height was negatively correlated with survival and spring cold hardiness. Shoot water potential and water use efficiency showed positive correlations with leader growth in the field. These data have relevance to the selection of families for the BC submaritime Douglas-fir tree breeding program. They can also help further our understanding of how growth and stress resistance traits interact, and provide information on inherent genetic control of these traits.

Pollen and charcoal analyses were used to reconstruct the Holocene vegetation and fire history of Pender Island (48°46’59” N, 123°18’11” W), located in the southern Gulf Islands on the south coast of British Columbia. A 9.03 m sediment core was retrieved from Roe Lake, a small, deep lake on Pender Island. Four AMS radiocarbon ages, the stratigraphic position of the Mazama tephra and a series of 210Pb ages were used to produce an age-depth model that estimated the base of the sediment core to be 9880 ± 126 calendar years before present (cal yr BP). The vegetation history from Roe Lake is similar to other paleoecological studies from the region. The early Holocene (10,000-7500 cal yr BP) was characterized by mixed woodlands with abundant Pseudotsuga menziesii and a diverse understory that included abundant Salix shrubs and Pteridium aquilinum ferns in these open canopy communities. An open Quercus garryana-dominated community with Acer macrophyllum and Arbutus menziesii in the canopy and xeric associations in the understory occurred from 7500-5500 cal yr BP. By 3500 cal yr BP, modern mixed Pseudotsuga menziesii forests with an increasingly closed canopy were established on Pender Island. Charcoal analyses of the uppermost sediments revealed low charcoal accumulation in the Roe Lake sediment core over the last 1300 years with a mean fire return interval of 100 years for the period before modern fire suppression, suggesting that fire was not a major control on plant community composition on Pender Island on this timescale. Fires were more frequent (i.e., every 47 years on average) during the Medieval Climate Anomaly with warm, dry conditions facilitating a higher fire frequency. Few fires (i.e., every 141 years on average) occurred between 1200-1850 AD, coinciding with the Little Ice Age. As climate was cooler and wetter during the Little Ice Age, fires during this time may reflect intentional burning by First Nations. In general, changes in vegetation and fire dynamics on Pender Island correlate well with changes in climate throughout the Holocene period, suggesting that climate change was likely the principal mechanism driving plant community composition and changes in the fire regime. / Graduate

Paleoecological analyses of an alkaline fen in the southern Interior Plateau of British Columbia, Canada were undertaken in association with ancient earth ovens. Local and regional vegetation and natural disturbance regimes were reconstructed using pollen, plant macrofossils and macroscopic charcoal. At White Rock Springs, Artemisia-Poaceae steppe occurred in the early Holocene and the inferred climate from this period was warmer and drier than present. Increasing moisture at 6000 14C yr BP fostered development of open Pinus ponderosa forests surrounding the fen, with Pinus contorta var. latifolia expanding at higher elevations. A slope-wash event likely resulting from root processing activities occurred in the late Holocene that resulted in 13% Asteraceae Tubuliflorae pollen at 2200 ± 80 14C yr BP. Macroscopic charcoal concentrations increased following this disturbance. Shortly after this time a modern open mixed conifer forest with Pseudotsuga menziesii was likely established. A second major ecological disturbance perhaps occurred within the last 200 years as indicated by fluctuating pollen values of P. ponderosa, Poaceae, Asteraceae Liguliflorae and wetland species. The fen’s vegetation history is consistent with regional records, but rapid changes during the late Holocene apparently occurred in response to disturbances. These disturbances are most likely linked to human root food harvesting and earth oven use, and later to ranching. Differentiation of P. ponderosa and P. contorta pollen types reveals intervals of local forest change that were not detected in previous studies. This study is part of a larger research project at Upper Hat Creek Valley including lithics, phytoliths, and patterns of earth oven structure. / Graduate

Douglas-fir develops a megagametophyte regardless of the pollination state of the ovule, whereas many other conifers develop a megagametophye in response to polli- nation. Megagametophytes in unfertilized ovules degrade two weeks following fertil- ization of the surrounding population. This is mediated by programmed cell death (PCD). Pollinated and unpollinated megagametophytes were dissected from Douglas- fir cones and extracted for RNA, which was then used as input for sequencing. A transcriptome was assembled from this data and expression levels were calculated. The data were fitted to quadratic regressions to produce coexpression groups. There is no clear upregulation of PCD effectors in the unpollinated megagametophyte. Po- tential regulators of megagametophyte fate are present in the data. Some are as- sociated with ABA signalling and proanthocyanadin biosynthesis while others share similarity to known regulators of PCD. Seed development processes are represented in the expression data, which support current knowledge of conifer seed development and provide targets for research. / Graduate / 0369 / 0309 / 0817 / igboyes@gmail.com

Thesis (M.S.)--Oregon State University, 1961. / Typescript. Includes bibliographical references (leaves 48-49). Also available on the World Wide Web.