A method of linking SORTIE-ND and PrognosisBC was developed for the purpose of predicting natural regeneration and forecasting future stand conditions in mountain pine beetle (Dendroctonus ponderosae Hopkins - MPB) attacked stands in the Interior Douglas-fir (IDF) and Sub-Boreal Spruce (SBS) biogeoclimatic ecosystem zones of central and southeastern British Columbia. PrognosisBC, a spatially-implicit growth model, lacked a submodel suitable for predicting natural regeneration in unsalvaged MPB-disturbed stands. To fill this gap, estimates of regeneration (trees <7.5 cm diameter at breast height - DBH) were supplied to PrognosisBC using the light-mediated forest dynamics model SORTIE-ND and the linked model was used to forecast future stand conditions. In order to improve results, a density-dependent system of crown allometry equations to predict crown depth and crown radius was developed and then added to SORTIE-ND. The equations used stand-level measures of stems ha-¹, basal area (m² ha-¹), and the basal area of trees taller than the target tree to explicitly account of the effects of crowding on the crown axes. Additionally, crown radius and crown depth were used as dependent regressors. The equations were fit using a nonlinear three-stage least squares estimator and generally provided good estimates of crown depth and crown radius for lodgepole pine (Pinus contorta var. latifolia), hybrid spruce (Picea engelmannii x glauca (Moench) Voss), Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and trembling aspen (Populus tremuloides Michx.). Tests of the hybrid model with the improved system of crown allometry equations were performed using reconstructed plot data collected from natural stands disturbed by MPB 25-years ago. The hybrid model provided good estimates (small mean bias and low root mean square error) for the basal area of advance regeneration (2 < DBH < 7.5 cm) for lodgepole pine (Pinus contorta var. latifolia). The best estimates were achieved when trees <7.5 cm DBH were transferred from SORTIE-ND to PrognosisBC 15-years after MPB-disturbance. For trees <2 m in height, poor estimates of stems ha-¹ where obtained. Despite the shortcomings with respect to trees <2 m tall, the results suggest that linking SORTIE-ND and PrognosisBC is an effective method of building a hybrid model capable of being used in MPB-disturbed forests. However, full parameterization of the SORTIE-ND model is likely needed to obtain accurate estimates for all sizes of natural regeneration.

The mountain pine beetle is associated with a diverse array of fungi. Grosmannia clavigera is the most pathogenic of these fungi. A comparison was made between two methods that have been used to assess fungal pathogenicity. Results were similar for older trees inoculated with G. clavigera using either the alternating flap technique or cork borer method. Using the cork borer method, younger lodgepole pine trees were inoculated with five different isolates of G. clavigera. After a 48 week incubation period, isolates ATCC 18086, B5 and H55 had induced stronger pathogenic indicators compared to isolates KW 1407 and B20. After a 7 week incubation period, only isolate ATCC 18086 had induced stronger pathogenic indicators. Usually, this isolate grew faster at lower temperatures and in a low oxygen environment. Isolate KW 1407 consistently produced milder pathogenic indicators during both incubation periods. Among the non-pathogenic fungal associates of the mountain pine beetle, Ceratocystiopsis minuta may be considered the most important because it is the type species for the genus Ceratocystiopsis. The history of this genus is complicated because no physical specimen exists for C. minuta. The phylogeny of the genus Ceratocystiopsis was evaluated. Many isolates of C. minuta were assessed as potential epitypes. Several isolates of C. minuta from previous work were shown to be misidentified. C. minuta isolate CBS 116796 is recommended for future genetic work within the genus Ceratocystiopsis. For morphological work, using measurements from the literature is recommended since CBS 116796 did not produce fruiting bodies.

In Lithuania, it is a first genetic study that analyses the DNA polymorphism of Scots pine at the level of cell’s nucleus and organelle’s genomes. In Europe, it is one of the first studies of DNR-based population structure covering in detail the eastern range of Scots pine, where the populations originate from Scotland in the west up to the Amur river estuary in the east. Our material represents a great magnitude of adaptive environments including the core populations at the central part of the species range as well as the marginal populations. The analysis was performed using high resolution and repeatability microsatellite DNA markers. / Tai yra pirmas genetinis mokslinis darbas Lietuvoje, nagrinėjantis paprastosios pušies DNR polimorfizmą ląstelės branduolio ir organoidų genomų lygmenyse. Europoje tai vienas iš pirmųjų mokslinių darbų, detaliai analizuojantis DNR polimorfizmą rytinėje paprastosios pušies rūšies arealo dalyje. Darbe lyginamos populiacijos, pradedant Škotija vakaruose, baigiant Amūro upės žiotimis tolimuose rytuose. Taip reprezentuojamas visas adaptacinių aplinkų gradientas: Europa–Uralas–Tolimieji Rytai. Tyrimui naudoti aukštos genetinės rezoliucijos ir patikimo pakartojamumo mikrosatelitinės DNR žymenys.

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<p>Quantifying carbon fluxes and pools of forest ecosystems is an active research area in global climate study, particularly in the currently and projected increasing atmospheric carbon dioxide concentration environment. Forest carbon dynamics are closely linked to the water cycle through plant stomata which are regulated by environmental conditions associated with atmospheric and soil humidity, air temperature and light. Thus, it is imperative to study both carbon and water fluxes of a forest ecosystem to be able to assess the impact of environmental changes, including those resulting from climate change, on global carbon and hydrologic cycles. However, challenges hampering such global study lie in the spatial heterogeneity of and the temporal variability of fluxes in forests around the globe. Moreover, continuous, long-term monitoring and measurements of fluxes are not feasible at global forest scale. Therefore, the need to quantify carbon and water fluxes and to identify key variables controlling them at multiple stands and time scales is growing. Such analyses will benefit the upscaling of stand-level observations to large- or global-scale modelling approaches. </p><p>I performed a series of studies investigating carbon and water fluxes in pine forests of various site characteristics, conditions and latitudinal locations. The common techniques used in these studies largely involved sap flux sensors to measure tree-level water flow which is scaled up to stand-level transpiration and a process-based model which calculates canopy light absorption and carbon assimilation constrained by the sap-flux beased canopy stomatal conductance (called Canopy Conductance Constrained Carbon Assimilation or 4C-A model). I collected and analyzed sap flux data from pine forests of two major species: Pinus taeda in temperate (36 °N) and Pinus sylvestris in boreal (64 °N) climatic zones. These forests were of different stage-related canopy leaf area and some were under treatments for elevated atmospheric CO2 concentration or fertilization. </p><p>I found that (Chapter 2) the 17-year long free-air CO2 enrichment (FACE) had little effect on canopy transpiration of a mixed forest with the dominant P. taeda and other broadleaved species as the understory in North Carolina, USA (Duke FACE). The result was due to the compensation of elevated [CO2]-induced increase of canopy leaf area for the reduction of mean canopy stomatal conductance. My next theoretical study (Chapter 3), comparing P. taeda (native at 36 °N in North Carolina), P. sylvestris (native at 64 °N in norther Sweden) and Pinus contorta (native at 58 °N in British Columbia, Canada) canopies, revealed that the interaction between crown architecture and solar elevation associated with site latitude of pine canopies affected the distribution and total amount of canopy light absorption and potentially photosynthesis such that the latitudinally prescribed needle organization of a pine canopy is optimal for light interception and survival in its native location. Then, I quantified and analyzed water fluxes in four pine forests: one composed of P. taeda in North Carolina and three containing P. sylvestris in northern Sweden (Chapter 4). The latter forests consisted of various stage-related canopy leaf area and nutrient status. Combining my estimates with other published results from forests of various types and latitudinal locations, I derived an approach to estimate daily canopy transpiration during the growing season based on a few environmental variables including atmospheric and soil humidity and canopy leaf area. Moreover, based on a water budget analysis, I discovered that the intra-annual variation of precipitation in a forest has a small effect on evapotranspiration and primarily affecting outflow; however, variation of precipitation across latitudes proportionally influences anuual evapotranspiration and outflow. Furthermore, the hydrologic analyses implied the `disequilibrium' of forest water cycling during the growing season when forests may use less and more water in dry and wet regions, respectively, than the incoming precipitation. Nevertherless, at annual timescale, most forests became in `equilibrium' by using similar proportion of incoming precipitation. Finally, (Chapter 5) I estimated and analyzed the temporal and spatial variabilities of carbon fluxes of the same four forests measured in Chapter 4 using the 4C-A computational approach and analyzed their resource-use efficiencies. I concluded that, based on my results and others as available, despite the differences in species clumping and latitudes which influence growing season length and solar elevation, the gross primary productivity can be conservatively linearly related to the canopy light absorption. However, based on previous findings from a global study, different allocation of the acquired carbon to the above- and belowground is regulated by soil nutrient status. </p><p>Overall, the findings in this dissertation offer new insights into the impacts of environmental changes on carbon and water dynamics in forests across multiple sites and temporal scales which will be useful for larger-scale analyses such as those pertaining to global climate projection.</p> / Dissertation

Radiata pine is a major plantation grown wood in the Southern hemisphere, but has inferior dimensional stability and low durability compared to other commercial species and the improvement of these features is the focus of this thesis. Specifically this thesis examines the dimensional stability, durability and mechanical properties of radiata pine after heat-treatment (160-210°C) in linseed oil. Changes in colour, micro-structure and chemistry with heat-treatment were studied. To optimise the treatment results, oil heat-treatment of wood was also carried out after thermo-mechanical compression of wood and the effect of the prior thermo-mechanical compression on stability, durability and mechanical properties were examined. The oil heat-treated wood turned uniformly darker in colour. The hydrophobicity (Water Repellence Efficiency-WRE up to 30%), dimensional stability (Ant-Swelling Efficiency-ASE up to 60%) and fungal resistance (up to 36%) were improved with the extent of the changes mainly depending on treatment temperature. However, the mechanical properties of oil heat-treated wood were reduced compared to the untreated control group. Accelerated UV weathering tests have shown that the oil heat-treated wood retained its colour and dimensional stability better than the untreated wood (the control group). The cell wall of treated wood was intact and no distinct structural changes were observed even at the most severe treatment (210°C for 6 hrs).The treatment resulted in changes to the wood chemical constituents, mainly the degradation of hemicelluloses which is believed to be principal reason for alterations in wood properties. A study of the effect of prolong heating on the linseed oil showed an increase in viscosity with heating time which in turn reduced the oil uptake and water repellency of treated wood. However, no significant difference in the colour and dimensional stability of the treated wood was noticed with oil of different heating ages. Oil absorbed by the wood during heat treatment was removed by organic solvent extraction and its contribution to the weight percentage change and moisture related properties were evaluated. The oil uptake percentage, determined by organic solvent extraction, was greater than the weight percentage loss that was deduced to occur during the heat treatment phase, which was attributed to mass losses or thermal degradation of wood constituents. Moisture excluding efficiency decreased after removal of the oil from treated wood, which suggested that the hydrophobicity of treated wood is affected by oil absorbtion. The influence of the post-treatment cooling period on properties of treated wood was studied separately. Oil uptake increased substantially with the post-treatment cooling time which in turn affected the hydrophobicity of treated wood although this effect was less important to dimensional stability. The loss of mechanical properties due to heat-treatment was successfully countered by thermo-mechanical compression of wood prior to the oil heat-treatment. The wood was compressed to 39% of its original thickness without any visible surface checks and cracks. Spring back and compression set recovery in densified wood decreased after oil heat-treatment. This combination treatment also resulted in improved fungal resistance compared to untreated wood. From this research, it is concluded that oil heat-treatment of radiata pine wood can improve its dimensional stability and durability obviating the need to introduce any persistent toxic chemicals. Thermo-mechanical densification of wood prior to oil heat-treatment can countered the loss of mechanical properties due to heat-treatment. The heating oil can be re-used in subsequent treatments and oil uptake can be minimised by limiting the post-treatment cooling time without any significant effect on the dimensional stability of treated wood.

Pinus radiata is the most planted tree in the southern hemisphere. The planted trees are especially susceptible to pathogens, but even the native population, nowadays limited tomerely five locations, are threatened by diseases caused by arthropods, fungi and dehydration. Endophytes are bacteria or fungi that reside inside healthy plant tissue, and often have a beneficial effect on their hosts. Endophytes can help plants adapt to abiotic stress such as drought and protect them against pathogens and insect pests. Given the roles that endophytes play in host stress responses, it is possible that without studying endophytes we may not fully understand a plant’s response to increased temperatures and climate-induced disease.Using Illumina-sequencing of the 16S rRNA-gene the bacterial endophyte community in 15 trees from three of the remaining native populations were studied. By investigating trees from several sites geographical community differences were discovered. The three overall most dominating bacterial taxa can all be connected with genera known to contain members withanti-fungal properties.

A somatic embryogenic system was created using material from the British Columbia Ministry of Forests and Range’s Sitka Spruce (Picea sitchensis (Bong.) Carr) breeding program for resistance to the white pine weevil (Pissodes strobi Peck.). The goal was to provide a system that could aid in understanding the phenotypic and genotypic variation that exists in these traits. Embryogenic lines were derived from controlled crosses of parental genotypes previously ranked for the abundance of three physical bark traits: sclereid cells, constitutive resin canals and traumatic resin canals. The number of filled seeds per cone from controlled pollinations was low, with a mean of 9.4 ± 6.8 (mean ± SD), compared to open-pollinated material, which had greater than 40 seeds per cone. The mean induction rate (to embryogenic cultures) was 7 %, ranging from 0 % to 56 % by cross. Of 135 genotypes, 88.1 % produced mature embryos. The number of embryos produced varied by culture. Nearly all (44 of 45) genotypes germinated, with a mean germination rate of 80 %. The overall conversion rate of somatic embryos to plants was 5.5 %. A novel method of cryopreservation that used a temperature pretreatment but did not require dimethyl sulfoxide was tested. Embryogenic cultures were recovered from 31 % of genotypes (n = 112). Genotypic and phenotypic variation were observed during each stage of the somatic embryogenic process. This project demonstrated that somatic embryogenesis and cryopreservation can be used to create a system to study phenotypic and genotypic variation in Sitka spruce. / Graduate

The defence mechanisms expressed in roots of Pinus sylvestris seedlings challenged with fungal pathogens were investigated, and a comparison was made between the expression of defences in non-mycorrhizal and mycorrhizal seedlings. Papillae were formed by cortical cells of non-mycorrhizal seedlings infected with Cylindrocarpon destructans. Histochemical evidence was obtained for pectic materials comprising an important polysaccharide component of these structures, and for the deposition of polyphenolic compounds also. Proton induced X-ray emission (PIXE) microanalysis indicated that insoluble calcium levels were elevated in papillae relative to normal cell walls. Although papillae appeared important in protecting cortical cells against penetration by fungal hyphae, a primary role for the wall appositions in the resistance of seedlings of Scots pine against root pathogens could not be proven. Although phytoalexins were not detected in the roots of Scots pine seedlings following infection with C. destructans, the mean content of an abietic acid fraction (comprising six compounds, of which only dehydroabietic acid could be positively identified), increased from 5.2 to 9.7mg g^-1 dry weight. This fraction exhibited some antifungal activity. -related proteins induced de novo by infection could not be detected, but several constitutive apoplastic proteins, including some with chitinase activity, appeared to increase in the needles of root-infected seedlings. The formation of ectomycorrhizae with Pisolithus tinctorius, Suillus bovinus and Hebeloma crustuliniforme did not itself induce papilla formation in the roots of P. sylvestris. Evidence was obtained to suggest that the response was suppressed when mycorrhizal seedlings were challenged with C. destructans. Results highly suggestive of the induction of systemic resistance in P. sylvestris seedlings, consequent upon mycorrhizal infection, were obtained. In seedlings grown in vitro the survival rate of mycorrhizal seedlings challenged aerially with Botrytis cinerea was 37.5% compared with 7.1 in seedlings grown gnotobiotically. However, the physiological mechanisms by which this protection was imparted remain to be determined.