The increase of discrete populations of dwarf mistletoe (Arceuthobium americanum Nutt.) plants or infections was studied in 20 year old stands of lodgepole pine (Pinus contorta Dougl.). Mistletoe infections were selected from infected trees in three areas 100 to 200 ft. in diameter. The age of each infection was determined by dissecting the infected host wood. It was found that the number of infections established annually had increased logarithmically during the preceding 8 to 10 years. Therefore the logarithmic rates of increase in the number of infections could be calculated to describe the past epidemic growth of each mistletoe population. The logarithmic rates (equivalent to "compound" increase of 66 to 96 per cent per year) demonstrated rapid population increase. Although the three mistletoe populations had developed in apparently different environments, the population rates of increase were not statistically different. However, for the study of ecological aspects of dwarf mistletoe epidemics this approach appears quite promising. / Forestry, Faculty of / Graduate

This study reports on the early effects of the Trifolium hybridum-Rhizobium symbiosis on Pinus contorta Doug, ex Loud (lodgepole pine), soil, and selected native plant species. Four rates of seeding (0, 10, 20, and 30 kg/ha) using inoculated Trifolium hybridum (alsike clover) seed were applied to three different site preparation treatments (broadcast burn, windrow burn, and mechanical scraping) using a split-plot design. Alsike clover and the Rhizobium inoculant were found to have excellent establishment and infectivity, and the symbiosis was assessed to be fixing nitrogen effectively. No effect of site preparation treatments was observed on establishment of the symbiosis, and clover-seeded plots averaged 76% cover by the end of the third growing season. The symbiosis had no significant (p < 0.05) effects on lodgepole pine total or incremental height or survival during the first three growing seasons, nor was there any observed effect on lodgepole pine foliar total nitrogen (N) concentration and ઠ¹⁵N values at the end of the second growing season. Small, but significant (p < 0.05) decreases were observed for lodgepole pine total and incremental diameter in the second and third growing seasons, as well as needle mass in the second growing season. The growth decreases were probably attributable to the effect of shading by the clover cover. However, lodgepole pine seedlings overtopped the clover by the end of the third growing season and shade effects are likely to decrease as tree seedlings continue to grow. After one growing season, the symbiosis significantly (p < 0.05) increased mineralizable N in the forest floor and mineral (0-15 cm) soil layers. However, no significant changes in total N were detectable. The changes in mineralizable N were likely a measure of increased microbial biomass attributable to greater amounts of rhizosphere soil in clover-seeded plots compared to controls. Available phosphorus (P) in the forest floor significantly (p < 0.05) decreased as rate of seeding increased after one growing season. The decrease of forest floor available P may be attributed to greater assimilation of P in clover-seeded plots for plant and microbial growth, as well as the additional requirements for P in the supply of biological energy needed for active N₂ fixation. All native plant species had low cover values which made interpretation of results difficult. However, percent cover of Calamagrostis canadensis, Rosa acicularis, and Spiraea betulifolia were significantly less in clover-seeded plots compared to controls at the end of the second growing season. Replacement of some herb and low-growing shrub species by legume-Rhizobium symbiosis may be desirable if the net result is an increase in site N without detrimental effects to tree crop species. It is recommended that the legume-Rhizobium symbiosis be established in the early regeneration of lodgepole pine plantations on similar sites that are inherently N deficient and have experienced further site N depletion through forestry practices such as slashburning. / Forestry, Faculty of / Graduate

The objectives of this study were to define the life history of the lodgepole terminal weevil (Pissodes terminalis Hopping) in the Cariboo Forest Region, to quantify the magnitude of damage resulting from weevil attacks, and to determine if P. terminalis activity was associated with measurable tree and stand parameters such as leader dimensions and density. Four study plots in juvenile lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands near Riske Creek, B. C. were selected to provide data on the biology of the lodgepole terminal weevil. In each plot, weekly collections of 10 weevil-attacked terminal shoots were made from June 3 to August 29, 1980, and monthly collections were taken during September through November. All leaders were dissected and the numbers of each P. terminalis life stage and associated predators/parasitiods were recorded. Seventy-one survey plots in lodgepole pine stands between 8 and 29 years of age throughout the Cariboo Forest Region were assessed for weevil activity. Each survey plot contained 25 trees over 2 metres in height, and each tree was measured for height, diameter at breast height, leader length, and basal leader diameter. Stand age, elevation, density, and all weevil attacks (including year of attack and type of resultant stem deformity) were also recorded. Weevil development appeared to be fairly uniform regardless of stand density and/or elevation; therefore, the data from all four biology study plots were combined to construct a life history diagram. In 46% of the survey plots one or both of the leader dimensions was significantly greater for attacked trees as compared to unattacked trees. In 28% of the plots attacked trees were either significantly taller or larger in diameter. Over 50% of the trees in stands of less than 4,000 stems per hectare had been attacked by P. terminalis at least once. Severe stem deformities such as forks and "stag-heads" comprised a larger proportion of damaged trees in the lower stand density classes. Weevil activity appeared to be higher in 1980 than in 1979. It was concluded that the lodgepole terminal weevil is currently a widely distributed and serious pest of young lodgepole pine stands in the Cariboo Forest Region. Given the present levels of weevil-caused damage as well as the possibility of future attacks, it was recommended that the activity of P. terminalis be considered when silvicultural practices such as juvenile spacing are undertaken in these stands. / Forestry, Faculty of / Graduate

The purpose of this study was to determine whether branch gall size of lodgepole pine can indicate the level of resistance towards Western Gall Rust. The diameters of galls were measured from different infection years on the same individuals. The ratio of Gall diameter to Branch diameter was calculated and then correlated with gall incidence. An additional statistical test of Completely Random Design was conducted in hopes of answering the objective. The results suggest that branch gall size cannot indicate level of resistance towards Western Gall Rust.

Thesis (M.S.)--Oregon State University, 1989. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Tree and tree component weights of 63 forest-grown lodgepole pine trees were investigated. Data were collected from one tenth-acre plot located in south western Alberta. Both graphical and multiple regression techniques were used. Of the independent variables tested, tree basal area was most closely related to the component weights, with the exceptions of bole bark weight and total stem dry weight. The fresh and dry weights of bole bark were most closely associated with tree height, and total stem dry weight was most closely associated with dbh. Very reliable estimates of tree and tree component weights were obtained using regression techniques and the independent variables previously mentioned. The proportions of the component weights of the total tree weights were determined. The proportions were highly variable and widely dispersed about the mean. The tree characteristic most closely associated with the various proportions varied for the component being analysed. The proportion of the total tree weight contained in the stem, slash, bark and bole wood decreased with increasing tree size. The proportion represented by the needles, branches, merchantable stem, and crown increased with tree size. The crown and needle characteristics of lodgepole pine were investigated. Tree size, whether measured as stem weight in pounds or cubic foot stem volume (ob), was most closely correlated with dry needle weight (in pounds). The number of needles per cubic foot of stem volume increased with increasing tree size. The needle characteristics of lodgepole pine are highly variable. Needle length was significantly related to needle width. Needle length was not significantly related to any tree characteristics. The need to develop reliable sampling methods for biomass and fire control studies was discussed. Double sampling with regression appeared to offer accurate estimates with a minimum of weight measurement. The number of trees required to obtain a sample mean within plus or minus 10 per cent of the population mean at the 95 per cent confidence level is too large to be practical for most biomass and fire control studies. A higher standard error of estimate is probably more desirable, thus allowing a greater number of conditions to be sampled in order to increase the representativeness of the study. The mutual relationship between tree weight and tree volume was investigated. Tree volume was highly correlated with tree weight. Reliable estimates of tree weight were obtained from tree volume. Variation in moisture content and specific gravity, within and between trees was analyzed. These variables were surprisingly uniform and appear to pose only minor problems in weight scaling, for lodgepole pine. / Forestry, Faculty of / Graduate

Long term management of lodgepole pine depends, in part, on the nutrient capital of the site. Harvesting has been shown to increase the availability of nitrogen and other nutrients for a limited period of time. This increase, or nutrient flush, following cutting has been attributed to several factors including changes in organic matter quantity and quality, soil moisture and temperature regimes, and competition for nutrients. Knowledge of the duration and the magnitude of the nutrient flush would be valuable for management decisions. A consequence of lodgepole pine clearcuts was studied for soil nitrogen availability and microclimate. Mineral soil and forest floor samples were anaerobically incubated and analyzed for ammonium-nitrogen (ppm). The mineral soil showed a flush lasting about 12 years, peaking by year 8, while the forest floor material showed no trend. The size of the increase from year 2 to year 8 was about 52%. Temperature (air and soil), soil moisture, solar radiation, and precipitation data were collected, and a soil water budget was calculated using a simple water balance model. The average calculated soil water deficit was 119 mm, but this may have been an over-estimate. Windrowing following cutting may have depleted the site nitrogen reserve which in turn reduced the amount that was mineralized during incubation. The interaction between the soil temperature and moisture may have further limited nitrogen availability to the lodgepole pine trees. It is concluded that the dynamics of nitrogen availability following clearcutting are important for the establishment and growth of lodgepole pine. The summer moisture deficit appears to limit the nitrogen mineralization rate as well as seedling growth. / Forestry, Faculty of / Graduate

Outbreaks of mountain pine beetle (Dendrcctonus ronderosae Hopk.) are common in lodgepole pine forests cf western North America. Characteristics of both the tark beetle and its host tree were compared using field replicates cf epidemic and endemic areas to test for any possible intrinsic differences between populations cf trees cr insects in these two different states. laboratory studies were conducted on beetle dispersal characteristics and cn effects of attack density and female parent size on beetle reproductive success and offspring size. Results are as follows: Trees in outbreak areas are older than in endemic regions, and trees of a given size and beetle attack density are more likely to be overcome and to permit successful beetle reproduction in epidemic than in endemic areas. However, tree spatial distributions, average attack densities and proportions of trees unsuccessfully attacked by beetles dc net differ consistently between epidemic and endemic areas. A method (in which blue-staining fungi were inoculated into trees) of measuring potential of trees tc resist mountain pine beetle was tested and found to be inadequate. Epidemic and endemic bark beetles did not differ consistently in dispersal, size, cr reproductive characteristics. However, early emerging beetles were larger than late emergers and females had a larger coefficient of variation in size than males. Field and laboratory data shew that the number of offspring emerging per parent decreases with increasing attack density. Breeding experiments further indicated that, 1) small female parents produce fewer and smaller offspring than large females, 2) small female parents produce female offspring with more strongly bimcdal size distributions than large females, and 3) high parental attack densities result in smaller offspring. Dispersal studies on the insect using chemical extracts of lodgepole pine bark showed that early emerging beetles are more likely to respond positively to tree chemicals than late emergers with the same flight history. Increasing lengths of flight increase female but not male responses to these chemicals. Evidence from a simulation model is presented tc support the hypothesis that the age at which lodgepcle pine normally becomes susceptible to mountain pine beetle attack is clcse to the age at which certain tree fitness measures are maximized. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 89-98).

The growth and productivity of British Columbia’s interior forests is largely limited by soil nutrient availability. Fertilization has been shown to be an effective silvicultural tool for increasing the development of immature stands throughout the region. This has lead to increased interest in long-term, repeated fertilization as a means of addressing timber-supply shortfalls as a result of the current mountain pine beetle (Dendroctonus ponderosae) outbreak. However, there is little information related to the impacts of repeated fertilization on the cycling of nutrients in many of these stands. This study makes use of a long-term (13-15 year) fertilization experiment in two lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm) and two interior spruce (Picea glauca [Moench] Voss and Picea engelmannii Parry) forests in the central interior of British Columbia subject to two levels (periodic and annual) of nitrogen(N)-based fertilization. The primary goal of the project was to examine the effects of different fertilizer regimes on aspects of soil chemistry. Specifically, this project was concerned with the impacts of repeated fertilization on: 1) soil carbon (C) and N cycling, and 2) soil base cation (e.g., Ca, Mg & K) availability. Soil and foliar nutrient regimes were quantified throughout the 2008 and 2009 growing seasons using ion-exchange membrane (IEM) plant root simulator (PRS) probes and traditional soil and foliar analyses. Fertilization increased N cycling at all sites, with generally elevated soil and foliar N and significant soil-foliar N relationships in several cases. Nitrate (NO3 -) increased in the fertilized plots in several cases; however, there was minimal evidence of NO3 - leaching. Greater than 90% of fertilizer-N inputs were retained onsite, suggesting these forests are not N-saturated. Soil, tree and total ecosystem C generally increased in response to fertilization, with the spruce sites exhibiting greater C accrual per unit of fertilizer N than the pine sites. Further, significant linear relationships between soil C and N were evident at all sites. At sites with poorly buffered soils (pH < 4), fertilizer treatments generally led to increased soil acidification and decreases in soil and foliar Ca. Decreases in soil Ca may have been due to significant increases in sulfate leaching; whereas foliar Ca decreases appear to be related to compromised uptake systems, potentially from increased soil aluminum. Buffering capacities, rather than forest type, appear to be the best predictor of soil and foliar Ca responses to fertilization. Despite significant changes in soil chemistry at all four sites, it does not appear that current fertilization rates are detrimentally affecting tree growth. / Graduate