Thesis (M.S.)--Oregon State University, 1985. / Typescript (photocopy). Includes bibliographical references (leaves 151-161). Also available on the World Wide Web.

The distribution, population ecology, behavior and host interactions of the root weevil, Hylobius warreni Wood were investigated in lodgepole pine forests in Alberta. Highest incidence of the weevil occurs in the Lower Foothills Section of the Boreal Forest Region, between 2,500 and 4,000 feet in elevation. In even-aged forests weevil numbers are distributed according to stand maturity, stand density, tree size and duff depth. Interactions between these variables modify the patterns of abundance in different stands. Attack incidence upon the host varies, being highest in the collar zone and least on lateral roots. As tree size increases the ratio of weevils on roots/weevils on collar tends to increase. During normal stand development initial invasion of weevils occurs at age 6-10 years, and persists with successive attacks throughout the life of the stand. Weevil populations are highly aggregated in mature stands; "k" values of the negative binomial varied from 0.09 to 0.68, while Taylor's power law gave an aggregation index "b" value of 1.92. Estimates of weevil populations indicated that low levels are characteristic of this species and are maintained, mostly within the range 200-1200 weevils per acre. Estimates of absolute numbers indicate similar levels of abundance occur in young and old stands alike, while population intensity values increase with stand maturity. The highest rate of increase of attack density per tree appears to occur during the ages of 30-45 years. The structure of weevil populations was described and mortality factors were identified and measured for larval, pupal and teneral stages. The main mortality factor of these stages appeared to be from excess moisture in the larval gallery and pupal cell. Only the first 3 larval instars are definable by head capsule width measurement. The feeding behavior of larvae varies with its maturity. In the early instars the feeding pattern relates to bark thickness, but damage is insignificant. Damage of late instars may consist of decorticated gallery lengths up to 24 cm. Larval and pupal habitats are described to indicate the special adaptations for survival. Adults live at least 3 years but lay their eggs during the second and third summers of adulthood. Their seasonal peak of activity occurs in June and early July. Dispersion in the forest tends to be random, commencing about 2 hours after sunset and when temperatures exceed 36-40 °F. Host trees are located partly by vision, the pattern of selection being related to host size. Maximum fecundity per female per season may be 36 or more eggs, but in the field the actual number may not exceed 12.0. Most eggs are deposited singly in niches excavated by the female in the root-collar bark, and are subsequently covered over with excreta. The egg requires a moist environment maintained for up to 42 days for successful hatch. During stand development up to 100 percent of trees may sustain larval feeding damage accumulated to various degrees of intensity. Young trees up to 30 years of age show less resistance to girdling damage than older trees, and reasons are given for this. Estimates of mean height losses of 20-25-year old tree stems sustaining 50 percent girdling were 11.5 and 10.9 percent over 2- and 3-year periods respectively. The total impact of the weevil in the stand as a whole appears to hasten successional changes during stand development. A method of regulation of weevil abundance is postulated and takes into account the behavior of the female during oviposition, host selection, larval feeding habits, cumulative damage and host interactions. Overall numerical restraint and stability of numbers are considered to be effected largely through the inherent behavior of adults. Several weevil control measures are suggested through forest management. Clearcutting of mature timber in alternate strips reduced a weevil population by an estimated 67 percent, but some larvae developed to adults in the cut stumps one and two years after tree removal. The effect of cutting resulted in a concentration of weevils on adjacent trees along stand peripheries, 3-5 years after cutting. / Forestry, Faculty of / Graduate

The needle chlorenchyma of Pinus contorta Dougl. ex Loud spp. Lat? - folia (Engelm. ex Wats) was fixed on site in the sub-alpine forests of the southern interior plateau of British Columbia, in order to conduct comparative observations by light and electron microscopy on the chloren-chymal cytology in summer and winter. Material fixed in the growing season (summer) demonstrated a chlorenchymal ultrastructure similar to that of other mature higher plant chlorenchymal tissues. Material fixed in mid winter (usually at below freezing tempertures) revealed extensive changes in the structural and positional aspects of most cytoplasmic components. Some of the most dramatic changes in the chlorenchyma cytoplasm in the winter state are as follows: chloroplasts became irregularly shaped and clumped together usually in certain specific areas of the cell; close associations form between the outer membranes of adjacent chloroplasts, these areas may lead to the apparent fusion of some chloroplasts. The cytoplasm became massively vacuolated, particularly in areas removed from the nucleus or the chloroplast clumps. The extent of this vacuolation can be deduced from the use of the adjective "foamy" to describe the extent and degree of these vacuolated cytoplasmic areas. Associated with the cytoplasmic winter vacuoles were highly osmiophilic bodies. A distinct seasonal cycle of cytoplasmic oil reserves was also noted. The reaction of the winter chlorenchymal cytoplasm to extentive manipulation in fixative osmotic potential was remarkably conservative. This observation allows inferences to be made about the permeability characteristics of winter cytoplasmic membranes. In order to verify the observed winter changes, chemical fixation studies were supplemented by observations on material collected, transported, stored, sectioned and observed by light microscopy in the frozen and unthawed, stained or fixed state. This work was conducted with specially designed transport devices and a cryomicrotome and cryomicros-cope. Observations were also conducted in summer and winter on the chlorenchyma of Pinus albicaulis Engelm and Tsuga mertensiana (Bong.) Corr. collected near timberline at the Whistler mountain ski resort ninety miles north of Vancouver. Observations from the cryomicroscopy of Pinus contorta needles indicate that the seasonal changes are not artifacts of chemical fixation procedures. Observations on the needles of the two conifer species collected at Whistler mountain indicate that the detailed seasonal observations on Pinus contorta may also apply to the needle chlorenchyma of other conifer species. A possible spring transitional stage between the winter and summer ultrastructural appearance of Pinus contorta chlorenchyma is discussed. Related experiments were conducted to indicate what effects the needle age of field trees had on winter-summer comparisons, and what effect drought stress and artificial hardening and freezing had on chlorenchymal ultrastructure. The drought and hardening-freezing experiments were conducted on laboratory grown trees in controlled environment chambers. No clear relationship between frost hardiness and drought stress was established. Experiments on the artificial inducement of frost hardiness in seedling trees were not considered successful. / Science, Faculty of / Botany, Department of / Graduate

Dwarf mistletoes are Parasitic flowering plants that infect conifer tree species. The effects of Arceuthobium americanum on the seed crop of Pinus contorta were examined over a two year period to evaluate the effects of altered host reproductive success on host population dynamics. Heavily infected trees produced significantly fewer cones than uninfected trees during the first season in which cones were collected. Cone length, number of seeds per cone, individual seed mass, and total calories per seed were significantly reduced in moderately and heavily infected trees. Trees with different levels of infection showed trends consistent with the above but no significant differences were observed during the second season. The number of seeds that were produced, disseminated, and that germinated per square meter of forest floor was significantly less in heavily infected plots than in lightly infected plots. Survival of one year old seedlings, however, was significantly higher in heavily infected plots. Significant increases in the abundance of woody litter due to increases in mortality of mature trees and witches brooms were positively correlated with increases in seedling survival in heavily infected plots. Survival of trees less than 45 years of age also increased as the level of infection in plots increased. This increases the fraction of total density that saplings represent in heavily infected stands. The total basal area of plots with different levels of infection were uniform, implying that all available environmental resources are being utilized. The differences in age distribution between lightly and heavily infected plots, however, indicate that resources are partitioned differently between saplings and mature trees in plots with different levels of infection. Dominant host trees experienced higher mortality in heavily infected plots than in lightly infected plots. This reduces the total biomass of all mature trees. Increased mortality of dominant host trees frees resources which reduces intraspecific competition thereby contributing to increased sapling survival in heavily infected plots. Consequently, stand density increases as the level of infection increases.

Soil texture, organic matter content, and hydrogen-ion concentration of soil samples were determined to find the correlation between soil characteristics, seed germination and seedling establishment of Pinus contorta. Scarification and stratification were treatments used for determining germination requirements of dormant seeds. Seeds were planted in different soils and experiments were conducted to determine the effects of different light intensities, temperatures, and depths of the water table on apparent photosynthesis rate and seedling establishment. Soil samples, pine cones, and young trees needed for the experiments were collected near Lily Lake, in the Uintah Mountains. The greatest and the fastest germination was found in soil with high organic matter and low PH. Seedling establishment succeeded only in mineral soil. Lodgepole seedlings grown in three fourths of full light had the best growth in both shoot and root systems. Low temperature favored photosynthesis rate more than respiration rate. Lodgepole seedlings preferred a moderately deep water table, since this species has a shallow absorbing system and not very extensive lateral roots.

This study examined shrinkage and related characteristics of two North American varieties of lodgepole pine: Pinus contorta var. latifolia and Pinus contorta var. murrayana, sampled at 10% of tree height. For var. murrayana, size was the only factor that had a significant effect on specific gravity; specific gravity decreased with increasing tree diameter. For var. Iatifolia, latitude was the only factor that had a significant effect on specific gravity; in general, specific gravity increased with increasing latitude. Conversely, specific gravity had a significant effect on radial shrinkage, the radial shrinkage tangential shrinkage ratio, and volumetric shrinkage for both varieties. The analysis of variance procedure indicated that the factors size, latitude, and elevation had no effect on the shrinkage of var. Iatifolia. However, for var. murrayana, radial shrinkage was affected by both tree size and latitude. Tangential shrinkage was also affected by latitude (increasing with increasing latitude). Linear correlations between radial shrinkage and growth rate, longitudinal shrinkage and distance I from the pith (a negative relationship), and specific gravity and growth rate were highly significant for both varieties. For var. Iatifolia, the linear association between specific gravity and heartwood percent was also significant. For var. murrayana, no difference in shrinkage or specific gravity was detected between the heartwood and sapwood. For var. Iatifolia, heartwood shrank less radially and had a lower specific gravity than sapwood. A comparison of the two varieties at their common latitudes indicated that murrayana trees have both higher specific gravity and shrinkage than do Iatifolia trees of the same size. / Master of Science

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Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 93-100). Also available on the World Wide Web.

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Arceuthobium americanum is a flowering plant which parasitizes Pinus contorta (Lodgepole pine). This study examined branch performance of P. contorta infected to varying degrees with A. americanum.