This research explores the capacity for functional photoreception in larvae of the mountain pine beetle (Dendroctonus ponderosae), an extremely important forest pest insect that is well adapted for development beneath the bark of pine trees. Phototaxis tests, gene expression analysis and development experiments were integrated to assess mountain pine beetle larvae for light sensitivity. When presented with a phototaxis choice test, larvae preferred dark over light microhabitats, revealing that larvae sense and respond behaviourally to light. Long wavelength opsin transcription was identified in all life stages, including eggs and larvae, suggesting that D. ponderosae possesses extraretinal photosensitive capabilities across its life cycle. The long wavelength opsin could function in phototaxis or the development phenology of immature beetles, while the ultraviolet opsin, only found to be expressed in pupae and adults, is likely to function in dispersal via the compound eyes. Results from two development experiments reveal an effect of photoperiod treatment on beetle development rate when reared from the egg stage, but not when reared from mature larvae, indicating that a critical photosensitive life stage(s) must occur in D. ponderosae prior to the third larval instar. An effect of photoperiod on adult emergence rates, however, appears to be independent of larval rearing conditions. The discovery of opsin expression and negative phototaxis in eyeless mountain pine beetle larvae, in addition to an effect of photoperiod on immature development and adult emergence rates, suggest that light and photoperiodism likely function in survival and life cycle coordination in this species. / Graduate / 2018-10-17

To address the scale mountain pine beetle (MPB) outbreak in British Columbia, salvage has become fully integrated with timber supply strategies. The objective of this thesis is to assess the economic impact of different salvage strategies depending on different attack levels, decay rates, and stakeholder discount rates. The study area is located in N.E. British Columbia where the MPB has not yet reached its peak and where susceptible to attack stands account for 40% of the area. Salvage strategies were modelled with a timber supply model (Woodstock) which uses a linear programming type II optimization approach. Performance of the model was assessed over a range of indicators such as NPV, profit, salvage proportion, species composition, inventory levels, and non-recoverable volume. Sensitivity analyses were conducted on harvest flow, discount rate, and ending inventory. The model was very sensitive to the intensity of attack and less sensitive to the decay level. The high level of attack resulted in large volume losses, mostly as un-salvaged inventory. Although allowable annual cut (AAC) uplifts have an economic benefit, they do not necessarily maximize the salvage of pine. Non-pine species are an important component of the salvage and these species are also essential for the future timber supply. If the objective is to ensure quality and quantity of the future forest, policies have to complement AAC uplifts by strongly encouraging the salvage of mainly pine-leading stands and management options that minimize the “by-catch” of non-pine species and minimize destruction of advanced regeneration during salvage. However, this has an opportunity cost for the private industry where the objective is to maximize profit. If the salvage strategy focuses on decreasing the impact on cash flows, achieving desirable ending inventory levels, avoiding salvage of stands after shelf-life, and reducing impact on non-attack species, then the current harvest level will likely lead to a mid-term timber supply fall-down. Using the fibre for bioenergy production is an alternative if managing for bioenergy can be integrated into harvest operations. However, unlike mill residues, the bioenergy supply has to fully account for harvest and transportation costs of dead wood to the mill. / Forestry, Faculty of / Graduate

Wildfires are a natural process critical to the health of forests around the world. However, recent decades have witnessed unprecedented wildfire seasons in many forested regions, leading to a range of unprecedented socio-economic, environmental, and human health impacts. Mitigating these impacts relies in part on fire behaviour prediction systems, which provide information to assist operational wildfire managers with addressing wildfire risk and prioritizing wildfire fighting efforts. A key aspect of fire behaviour prediction systems are rate of spread models that rely on observational and experimental fire behaviour data from naturally occurring wildfires and prescribed burns, respectively. Given the challenge with observing and measuring wildfires in situ, rate of spread models typically rely on a small set of data inputs that are not always representative of the range of wildfires occurring in certain forest types. Furthermore, existing fire behaviour models often lack empirical data on forests that have more recently experienced significant compositional shifts due to climate change or various ecological or anthropogenic disturbances. To address these shortcomings, the objective of this thesis is to establish a method of acquiring empirical fire behaviour data to enhance fire behaviour prediction science through two distinct studies. The first evaluates the utility of monophotogrammetry to extract fire behaviour data from oblique aerial wildfire photographs. The results demonstrate how this approach can provide new and accurate fire spread observations to inform fire behaviour prediction or other aspects of wildland fire science where databases of such wildfire photos exist. The second study is an empirical wildfire spread analysis in forest stands affected by mountain pine beetle (MPB), and utilizes the method of monoplotting to acquire spread rate data from wildfire photographs of grey-attack MPB-affected forest stands. Results from this study further demonstrate the efficacy of the previously established monoplotting technique while providing novel empirical evidence of fire behaviour in grey attack MPB-affected forest stands. Overall, the research results presented in this thesis demonstrate the potential of monophotogrammetry for the acquisition of fire behaviour data and evaluating the results derived from fire behaviour prediction systems in different ecological contexts. This thesis exhibits the potential for this method to expand into other areas of fire behaviour, such as flame or smoke plume dimensions, spotting, and the relationship between fire behaviour and disturbance events such as pest insect outbreaks. / Graduate / 2023-04-14

Pinus mugo Turra (sensu lato) is a prostrate shrub growing above the alpine timberline in the mountain ranges of Southern, Central and Eastern Europe. It is well adapted to the harsh alpine environment creating different mechanisms for survival. The research was carried out in Krkonoše Mountains on base of Pinus mugo individuals compared with Picea abies trees. Samples from shrubs were gathered using serial sectioning from four sites in different elevations located on Sněžka Mountain and Smogornia Ridge. Further analysis of the sampled material was made with the help of different detrending methods to see which method will return the best growth response to climate parameters. RCS detrending and detrending via simple averaging reflected the best climate signal contained in dwarf pine chronologies. The advantage of these methods is based on their ability to reflect growth conditions of the particular site. Upper sites showed significant correlations with temperatures of the growing season, while on lower sites the signal was quite unclear. The amount of precipitation plays the significant role on shrub growth during the vegetation period (especially July month) and early spring when water is very important for growth initiation. Upper Pinus mugo sites showed high sensitivity to droughts, especially...

The North American forest industry has long been an important part of North America’s economy. The industry has traditionally been the only industrial demand on timberland creating a long established balance between the supply (timberland) and the demand (manufacturing). Recently the forest industry has been troubled due to the collapse of the solid wood products largest market, housing, and a global recession. These troubled times have lead many operation in the industry to curtail operations. Since the industry curtailed, high oil prices and increasing environmental concern have advocated the investment in renewable energy sources. As a renewable energy source, biomass holds great potential for satisfying a portion of our continental energy demands. This increased demand for timberland products could be very profitable to the timberland owners but also holds many concerns to the extent of additional supply that can be harvested from our timberlands. Further complicating the balance of supply and demand are the large global and domestic effects that are reducing the total amount of timberland and increasing the demand for the remaining timberlands. The supply and demand changes have the potential to make the forest industry evermore important part of the North American economy but care must be taken to not over extend our resources.

Avec les changements climatiques et les perturbations humaines, de nombreuses espèces changent leurs aires de répartition. Dans ce contexte, l’identification de loci potentiellement adaptatifs chez ces populations en expansion est importante pour mieux comprendre le potentiel évolutif et la capacité d’envahissement de ces espèces. Toutefois, chez les espèces en expansion de territoire, tel le dendroctone du pin, les processus démographiques comme le surf d’allèles peuvent résulter en des patrons spatiaux de variation génétique neutre qui imitent ceux issus des processus adaptatifs. Ce phénomène gonfle le taux de faux-positif d’identification des loci adaptatifs et confond ainsi les méthodes de génomique du paysage. Dans le cadre de ce projet de maîtrise, j’ai étudié le développement des structures génétiques neutres et adaptatives lors d’une expansion de territoire. Je me suis attardé particulièrement sur l’influence de différentes conditions démographiques sur le taux de loci neutres qui imitent les patrons spatiaux de ceux adaptatifs, en menant une revue de littérature et en utilisant le système épidémique du dendroctone du pin pour paramétrer un modèle de simulations. J’ai simulé les dynamiques démographiques et génétiques des populations de dendroctones à l’aide du modèle de simulation génétique explicitement spatial CDmetaPOP. J’ai analysé les conséquences de trois facteurs sur le taux de faux-positif : 1) la capacité de dispersion; 2) le moment d’échantillonnage durant l’expansion de territoire; et 3) la force de sélection agissant sur le locus adaptatif de référence. J’ai démontré qu’une combinaison de faible capacité de dispersion, faible sélection et un échantillonnage tôt au début de l’expansion contribuent à un plus grand taux de faux-positif, alors qu’une forte capacité de dispersion conduit à de plus faibles taux de faux-positif. Lorsque les méthodes de génomique du paysage sont utilisées dans ces conditions, elles risquent d’avoir un haut taux de loci neutres identifiés comme adaptatifs et doivent donc être interprétées avec prudence. La situation démographique complexe que présente le système actuel du dendroctone (et d’autres espèces irruptives et envahissantes) rend l’identification d’allèles adaptatifs plus difficile. Les résultats de ce projet encouragent l’incorporation de ces processus démographiques dans les méthodes de génomique du paysage. / Under the actual climate changes and human perturbations global context, many species are altering their geographic range. The identification of putatively adaptive loci in those expanding populations is thus important to better understand evolutionary potential and invasiveness of these species. However, in irruptive species undergoing rapid expansion, such as the mountain pine beetle (MPB), demographic processes such as allele surfing can result in spatial patterns of neutral genetic variation that can mimic those that result from adaptive processes. This phenomenon inflates the false discovery rate of adaptive loci and thus confounds landscape genomics methods. In this thesis, I studied the development of neutral and adaptive genetic structure during a range expansion. I investigated precisely how different demographic conditions influence the rate of neutral loci mimicking the spatial patterns of adaptive loci, doing a literature review and using the mountain pine beetle outbreak system to parametrize a simulation model. I simulated the demographic and population genetic dynamics of mountain pine beetle populations undergoing range expansion using the spatially explicit, individual-based genetic model CDmetaPOP. I examined the consequences of three factors on the false discovery rate: 1) species dispersal capacity; 2) timing of sampling during the course of the expansion; and 3) the strength of selection on adaptive reference loci. I found that a combination of weak dispersal capacity, weak selection, and early sampling during expansion results in the highest rate of false positive, while strong dispersal was responsible for lower rates of false positive. Used under these conditions of dispersal capacity, strength of selection and sampling timing, landscape genomics models risk elevated false discovery rates of adaptive loci and must be interpreted cautiously. Complex demography in the current MPB system (and other irruptive and invasive species) makes identification of adaptive loci challenging. Results from this project clearly demonstrate that there is a need for further method development to include these directional demographic processes in the field of landscape genomics.