Whitebark pine (Pinus albicaulis Engelmann) is a treeline species in the central Rocky Mountains. Its occupation of high elevations previously protected whitebark pine from long-term mountain pine beetle outbreaks. The mountain pine beetle, however, is currently reaching outbreaks of record magnitude in high-elevation whitebark pine. We used a factorial laboratory experiment to compare mountain pine beetle (Dendroctonus ponderosae Hopkins) life history characteristics between a typical host, lodgepole pine (Pinus contorta Engelmann), and whitebark pine. We tested the effects of natal host and brood host on beetle fecundity, offspring size, and brood sex-ratio. We reared mountain pine beetles from whitebark pine and from lodgepole pine, and infested half of them into their natal host and half into the other host. Fecundity was greater overall in lodgepole pine brood hosts. Among lodgepole brood hosts, beetles from whitebark pine had greater fecundity. Fecundity was also significantly related to phloem thickness, which was greater in lodgepole pine. Offspring were larger from whitebark brood hosts than from lodgepole, regardless of their parents’ natal host. Finally, sex-ratio was closer to 1:1 in lodgepole than in whitebark brood hosts. We conclude that host species affects life history of mountain pine beetle with consequences for individual beetle fitness.

Over the last two decades, mountain pine beetle (Dendroctonus ponderosae) populations reached epidemic levels across much of western North America, including high elevations where cool temperatures previously limited beetle persistence. Many high-elevation pine species are susceptible hosts and experienced high levels of mortality in recent outbreaks, but co-occurring Great Basin bristlecone pine (Pinus longaeva), the longest-living non-clonal organism, were not attacked. I assessed Great Basin bristlecone pine resistance to mountain pine beetle by evaluating mountain pine beetle host selection behavior and reproductive success in this species. To evaluate mountain pine beetle host selection preference for Great Basin bristlecone pine, I used no-choice 48-hour attack box experiments that confined pioneering female beetles onto pairs of living Great Basin bristlecone and limber pine (P. flexilis), a susceptible host tree species. To investigate the effect of induced tree defenses on host selection behavior, I repeated the tests on paired sections of Great Basin bristlecone and limber pines that had been recently cut, thereby removing their capacity for induced defensive reactions to an attack. Mountain pine beetles avoided Great Basin bristlecone pine relative to limber pine, suggesting that Great Basin bristlecone pine has a high level of resistance to mountain pine beetle due at least in part to stimuli that repel pioneering females from initiating attacks, even when induced defenses are compromised. To investigate mountain pine beetle reproductive success in Great Basin bristlecone pine, I compared the mating success, fecundity, and brood production of mountain pine beetle parents placed in cut Great Basin bristlecone pine bolts with that of mountain pine beetles placed in cut bolts of limber pine and lodgepole pine (P. contorta), two susceptible species. Initial reproductive development was similar in all three tree species, but nearly all brood in Great Basin bristlecone pine died before emerging. The extensive offspring mortality observed in Great Basin bristlecone pine may be a key evolutionary driver behind mountain pine beetle aversion to the species. These findings suggest that Great Basin bristlecone pine is a highly resistant species with low vulnerability to climate-driven increases in mountain pine beetle outbreaks at high elevations.

Climate change is likely to disrupt the timing of developmental events (phenology) in insect populations in which development time is largely determined by temperature. Shifting phenology puts insects at risk of being exposed to seasonal weather extremes during sensitive life stages and losing synchrony with biotic resources. Additionally, warming may result in loss of developmental synchronization within a population, making it difficult to find mates or mount mass attacks against well-defended resources at low population densities. It is unknown whether genetic evolution of development time can occur rapidly enough to moderate these effects. The work presented here is largely motivated by the need to understand how mountain pine beetle (MPB) populations will respond to climate change. MPB is an important forest pest from both an economic and ecological perspective, because MPB outbreaks often result in massive timber loss. Recent MPB range expansion and increased outbreak frequency have been linked to warming temperatures. We present a novel approach to modeling the evolution of phenology by allowing the parameters of a phenology model to evolve in response to selection on emergence time and density. We also develop a temperature-dependent phenology model for MPB that accounts for multiple types of developmental variation: variation that persists throughout a life stage, random variation, and variation due to the MPB oviposition mechanism. This model is parameterized using MPB development time data from constant temperature laboratory experiments. We use Laplace's method to approximate steady distributions of the evolution model under stable temperatures. Here the mean phenotype allows for parents and offspring to be oviposited at exactly the same time of year in consecutive generations. These results are verified numerically for both MPB and a two-stage model insect. The evolution model is also applied to investigate the evolution of phenology for MPB and the two-stage model insect under warming temperatures. The model predicts that local populations can only adapt to climate change if development time can adapt so that individuals can complete exactly one generation per year and if the rate of temperature change is moderate.

This thesis has two data chapters that consider factors affecting loblolly pine health in localized regions of Mississippi. The first data chapter investigated the abiotic and biotic factors contributing to loblolly pine (Pinus taeda) mortality on private timberland in Mississippi. This assessment considered temperature and precipitation variations, bark beetle populations, foliar and root pathogen tests, and drone survey. The results revealed that the loblolly pine mortality resulted from combination of factors. The second data chapter examined the impact of habitat fragmentation on southern pine beetle (SPB; Dendroctonus frontalis) infestation in Homochitto National Forest (HNF). This was assessed through remote sensing and categorization of SPB spots in HNF over nine years. Results indicated that increased total pine patch area, decreased distance between pine patches, and low patch diversity are important drivers of SPB outbreak in HNF. These results can help improve loblolly pine health and management in the southeastern United States.

The hypothesis that stressed loblolly pine (Pinus taeda L.) could be distinguished from non-stressed loblolly pine by increased foliage temperatures was tested. The foliage temperatures of seedlings and trees were measured with an AGA Thermovision 680 system, imported by the AGA Corporation, Secaucus, New Jersey. The AGA Thermovision 680 system is a simple, easily transported remote sensing system for detecting relative apparent temperatures of plant foliage without direct contact with the leaves. This system is sensitive to infrared wavelengths in the 2-5.6 micron region of the electro-magnetic spectrum. Foliage temperatures in loblolly pine seedlings increased within one week of stress induced by drought, flooding, or severing. Increased temperatures of stressed seedlings were associated with reduced needle moisture content prior to visual symptoms of stress. Foliage temperatures of loblolly pine trees stressed by severing the bole were warmer relative to neighboring control trees. Increased temperatures were detected within one week after severing. Previsual detection of stress can be achieved by measuring foliage temperatures of loblolly pine. The AGA Thermovision should prove to be a useful tool for non-destructive sampling of plant stress, for locating stressed trees, and potential bark beetle infestations. / Ph. D.

Forest management practices which reduce southern pine beetle (SPB) risk benefit not only the landowners who perform them, but all those who draw benefits from southern pine forests in Virginia, especially other forest owners within the same region. One such management practice is pre-commercial thinning (PCT), which is particularly unattractive to non-industrial private forest (NIPF) landowners because of the substantial costs and delayed financial returns involved. Since the benefits to society generated by PCT are not fully realized by the individuals who might implement it, there may be a market externality in which PCT is underprovided across the landscape. The Pine Bark Beetle Prevention Program (PBBPP) has the potential to correct this externality by reimbursing a portion of the costs of PCT for landowners who qualify. However, cost share incentives have been criticized for being ineffectual on the basis that landowners substitute publicly funded reimbursement for private investment, without altering their management practices. To investigate the effect of the PBBPP cost share for PCT, a survey was sent to 1,200 NIPF landowners in seven counties across the Piedmont and Coastal Plain physiographic regions of Virginia, where southern pine is prevalent and SPB hazard is a relevant concern. To measure willingness to participate in the program, a referendum style question was used in which the offered cost share ranged from 20% to 90%. Results of discrete choice models estimated from survey data indicate that cost sharing has a significant, positive effect on willingness to participate overall, though increasing reimbursement above 60% is unlikely to affect participation. Some landowners are not responsive or are less responsive to cost sharing due to personal and property characteristics. / Master of Science

High-dose verbenone, verbenone plus nonhost volatiles (NHVs), and both semiochemicals in combination with aggregant-baited funnel traps were tested for stand- level protection against mountain pine beetle attack for two consecutive years (2004-2005) at three seral high elevation whitebark pine sites in the Greater Yellowstone Ecosystem. In 2004, two 0.25-hectare treatments comprised of 25 high-dose verbenone pouches or verbenone pouches combined with single baited funnel traps were tested in a push-pull strategy. In 2005, 25 high-dose verbenone and 25 NHV pouches, or verbenone and NHV in combination with baited funnel trap clusters were tested. In both years, treatments were compared to 0.25-hectare control plots with no semiochemicals or funnel traps. The proportion of trees attacked by mountain pine beetle in treated plots was significantly reduced, when compared to control plots, at only one site treated with verbenone in 2004, and at only one site in 2005. High-dose verbenone alone, verbenone and NHVs, and both semiochemicals combined with baited funnel traps in a push-pull strategy did not consistently reduce the proportion of mountain pine beetle attacked trees relative to control plots. No covariates tested, including stand density, beetle population size, or tree size were consistently significant in explaining proportion of trees attacked.

The mountain pine beetle (MPB, Dendroctonus ponderosae), a tree-killing bark beetle, has historically been part of the normal disturbance regime in lodgepole pine (Pinus contorta) forests. In recent years, warm winters and summers have allowed MPB populations to achieve synchronous emergence and successful attacks, resulting in widespread population outbreaks and resultant tree mortality across western North America. We develop an age-structured forest demographic model that incorporates temperature-dependent MPB infestations: the Susceptible-Infested-Juvenile (SIJ) model. Stability of fixed points is analyzed as a function of population growth rates, and indicates the existence of periodic outbreaks that intensify as growth rates increase. We devise analytical methods to predict outbreak severity and duration as well as outbreak return time. To assess the vulnerability of natural resources to climate change, we develop a thermally-driven mechanistic model to predict MPB population growth rates using a distributional model of beetle phenology in conjunction with criteria for successful tree colonization. The model uses projected daily minimum and maximum temperatures for the years 2025 to 2085 generated by three separate global climate models. Growth rates are calculated each year for an area defined by latitude range 42° N to 49° N and longitude range 108° W to 117° W on a Cartesian grid of approximately 4km resolution. Using these growth rates, we analyze how the optimal thermal window for beetle development is changing with respect to elevation as a result of climate change induced warming. We also use our combined model to evaluate if thermal regimes exist that would promote life cycle bivoltinism and discuss how yearly growth rates would change as a result. Outbreaks of MPB are largely driven by host tree stand demographics and spatial effects of beetle dispersal. We augment the SIJ model to account for the spatial effects of MPB dispersal throughout a forest landscape by coupling it with a Gaussian redistribution kernel. The new model generates a train of sustained solitary waves of infestation that move through a forest with constant speed. We convert the resulting integrodifference equation into a partial differential equation and search for travelling wave solutions. The resulting differential equation provides predictions of the shape of an outbreak wave profile and of peak infestation as functions of wave speed, which can be calculated analytically. These results culminate in the derivation of an explicit formula for predicting the severity of an outbreak based on the net reproductive rate of MPB and host searching efficiency.

This dissertation describes the development of CAMBIUM, an agent-based forest sector model for large-scale strategic analysis. This model is designed as a decision support tool for assessing the effect that changes in forest product demand and resource inventories can have on the structure and economic viability of the forest sector. CAMBIUM complements existing forest sector models by modeling aggregate product supply as an emergent property of individual companies’ production decisions and stand-level ecological processes. Modeling the forest products sector as a group of interacting autonomous agents makes it possible to introduce production capacity dynamics and the potential for mill insolvencies as factors in modeling the effects of market and forest inventory based disturbances. This thesis contains four main manuscripts. In the first manuscript I develop and test a dispersal algorithm that projects aggregated forest inventory information onto a lattice grid. This method can be used to generate ecologically and statistically consistent datasets where high-quality spatial inventory data is otherwise unavailable. The second manuscript utilizes this dataset in developing a provincial-level resource dynamics model for assessing the timber supply effects of introducing weevil-resistant spruce. This model employs a stand-level approach to simulating weevil infestation and associated merchantable volume losses. Provincial-level impacts are determined by simulating harvest activities over a 350 year time horizon. In the third manuscript I shift the focus to interactions between forest companies. I analyze the effects of strategic decisions on sector structure by developing CAMBIUM as an agent-based model of competition and industry structure evolution. The forest sector is modeled as a group of autonomous, interacting agents that evolve and compete within the limitations posed by resource inventories and product demand. In the final manuscript I calibrate CAMBIUM to current conditions in the British Columbia forest sector. Industry agents compete for roundwood inputs, as well as for profits in finished product markets for pulp, panel products, and lumber. To test the relevance and utility of this model, CAMBIUM is used to quantify the cumulative impacts of a market downturn for forest products and mountain pine beetle induced timber supply fluctuations on the structure of the forest sector.

In this study, two symbiotic fungi of Southern Pine Beetle (SPB), Entomocorticium peryii and Entomocorticium sp.A were evaluated in terms of polyphenol oxidase (PPO) production. The effect of different inhibitors, inducers and assay parameters such as temperature and pH on enzyme activity were investigated and maximum PPO activity was observed at 30&deg / C, pH 8.0 and when tannic acid was used as an inducer. Copper-chelator salicyl hydroxamic acid (SHAM) and pcoumaric acid, both indicated as inhibitors of tyrosinase and catechol oxidase significantly reduced the activity. For biochemical characterization studies, the enzyme was concentrated by ultrafiltration. To determine type of the enzyme, activity staining after Native-PAGE was carried out. Type of polyphenol oxidase produced by E. peryii and E. sp.A was determined as catechol oxidase by activity staining. However higher activity was observed on hydroquinone (p-diphenol) rather than catechol (o-diphenol). The enzyme obeys Michealis-Menten kinetics with Km and Vmaxvalues being 10.72 mM hydroquinone and 59.44 U/ml for E. peryii and 8.55 mM hydroquinone and 73.72 U/ml for E. sp.A respectively..