The usefulness of interspecific crosses between Sitka spruce (Picea sitchensis (Bong.) Carr.) and interior spruce (Picea glauca (Moench) Voss, Picea engelmannii Parry and their hybrids) was investigated in one coastal environment. For height growth and bud set most of the variation was at the regional and individual cross level, but very little variation was at the subregional level. The main genetic effects, male and female, accounted for a majority of the genetic variance and additive genetic effects are interpreted as the main factor in the determination of height growth and bud set. For bud set the maternal source of variation accounted for the majority of the genetic variance and a maternal influence on bud set is suggested. Some specific cross combinations were outstanding in height growth and non-additive genetic factors are considered important in these crosses. For bud break most of the variation was due to the residual error, although regions and crosses were statistically significant sources of variation. The Female*Male term was the most important genetic source of variation although bud break is not considered to have as much genetic variation as height and bud set. Large differences were found in the pattern of cold hardiness in the fall and it is considered that photoperiod plays a much larger role than previously thought, especially for interior spruce. Most of the variation was again at the regional and individual cross level. The intermediate performance of the hybrids suggests an inheritance of cold-hardiness based on additive genetic effects. Recommendations are given in the text for the use of these hybrids as well as the areas in which further research would be desireable. / Forestry, Faculty of / Graduate

In 1987, a research project, conducted in the interior of British Columbia, was undertaken in order to obtain preliminary fertilization response data for three interior species. In 1988, as part of this contract, 12 screening trials were established in young interior spruce stands in the north-central interior of B. C. using factorial combinations of nitrogen and "complete" mix fertilizer. Initial assessment of the unfertilized foliage obtained from the 12 installations indicated that all stands exibited low nitrogen and potentially low sulphur levels. After fertilization, the effects of the treatments were measured by needle weight response, nutrient concentration, and subsequent nutrient content response. In all 12 installations the largest needle weight response occured when the nitrogen and the "complete" mix fertilizers were combined.. In the treatments where nitrogen was applied alone, no significant change in needle size was recorded. Nutritionally, nitrogen fertilization resulted in large increases in nitrogen concentration, indicating this element was limiting. As well, nitrogen fertilization also produced large decreases in K, S, and S04-S concentrations. Nitrogen-only fertilization also caused large elevations in the N/S ratios to occur. This elevation in N/S ratios and the subsequent decreases in S and S04-S concentrations seem to indicate that nitrogen-only fertilization has a negative impact on the sulphur nutrition of interior spruce. The addition of the "complete" mix fertilizer was, in most cases, successful in returning the decreased nutrient concentration levels of K, S, and S04 and the elevated N/S ratios back to their original unfertilized status. From these results it appears that nitrogen fertilization of interior spruce should only be considered if it is accompanied by a mixture of other nutrients; the most important component being sulphur. / Forestry, Faculty of / Graduate

Site preparation treatments are often used prior to the planting of clearcut forest lands to improve planter access and to increase the number and quality of planting spots. Most mechanical site preparation treatments alter the configuration and material composition of surface soil materials, and can have marked effects on soil properties important to seedling survival and growth. Effects of some of these treatments on soil moisture, soil temperature, rates of nitrogen mineralization, and the establishment of Picea glauca x engelmannii seedlings were examined on fresh, moist, and wet sites in the moist cold subzone of the Sub-boreal Spruce Zone in west-central British Columbia. Four types of microsite alteration were investigated: forest floor removal (spot scalping), soil mounds over inverted sections of forest floor (inverted mounds), mineral soil mounds over a mineral soil surface, and inversion of the forest floor and mineral soil in place. Soil temperature was monitored continuously and soil moisture weekly at the 10-cm depth in 16 combinations of site and microsite treatment during two growing seasons. The response of seedling height and diameter growth was monitored for three growing seasons. Effects of altering soil temperatures through mechanical treatments on rates of nitrogen mineralization were examined by incubating a standard soil material in a range of microsites created by six combinations of site and mechanical treatment. Effects of substrate quality and soil temperature on rates of nitrogen mineralization were examined in paired mounded and untreated spots in fresh, moist, and wet sites. In all sites, early growing season soil temperatures in the seedling rooting zone were substantially warmer in inverted mounds than in other treatments. Spot scalping increased temperatures slightly relative to controls in the fresh site, but had little or no warming effect on moist and wet sites. Inverted mounds became substantially drier than other treatments during periods of low rainfall, particularly in the fresh site. After three growing seasons, seedling height growth was greatest in inverted mounds, irrespective of site. Amounts of nitrogen mineralized in a standard soil material during incubation for 77 days in the field were significantly greater for samples placed in inverted mounds than for those placed in other microsite treatments. There was a significant positive correlation between amounts of nitrogen mineralized during field incubations and degree hour sums calculated for associated microsite treatments and sites. Both substrate quality and soil thermal regime affected rates of N mineralization in samples from paired mounded and untreated spots, and an interaction was observed between the two factors. / Graduation date: 1991

For the high-elevation Engelmann spruce - subalpine fir (ESSF) biogeoclimatic zone of southwestern British Columbia, there is little empirical data on the long-term dynamics of subalpine spruce-fir stands. A lack of a long-term perspective on the growth and development of stands in the ESSF zone hinders both ecological research and silvicultural planning in the ESSF forest. A broadly-focussed pilot study on long-term Engelmann spruce-subalpine fir stand dynamics in the ESSF zone was designed to begin to address this deficiency. This study used two methodological approaches to gain insights into long-term stand dynamics: 1) a retrospective approach to examine historical patterns of: i) postfire conifer regeneration, ii) post-establishment stand structure development, and; iii) basal area production and accumulation in ESSF spruce-fir forests, and; 2) A chronosequence approach to examine overall stand basal area development over a 575-year chronosequence, which is not amenable to detailed retrospective examination. In order to reconstruct the patterns of postfire regeneration and subsequent stand development, measurements of tree age, diameter, radial increment, and height were collected in 8 mesic, 45- to 110-year-old fire-origin stands of Engelmann spruce (Picea engelmannii Parry. ex Engel.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in the ESSFwm and ESSFdc2 biogeoclimatic subzones of the North Cascades mountains. The results of the stand reconstruction were also used to aid in the interpretation of the chronosequence, which was based on basal area and age data from both the retrospective study sites, and the published literature. Based on the graphical analysis and discussion of the data collected in this pilot study, the following features of long-term stand development were noted in subalpine Engelmann spruce-subalpine fir stands: 1) Postfire conifer re-establishment on these burned ESSF sites was slow and erratic; the re-establishment period was 30 to 50 or more years in duration; 2) There appeared to be no consistent or predictable postfire patterns of conifer establishment on the various sites, either over time, or on a site-to site basis; 3) During postfire regeneration and immature stand development, there appeared to be no consistent differences between Engelmann spruce and subalpine fir, either in terms of i) postfire regeneration establishment, or ii) height development; 4) Fire-origin spruce-fir stands in the ESSF zone rapidly develop a complex stand structure, possibly due to the gradual and prolonged patterns of regeneration ingress on these sites; 5) Trees which have initial advantages in height or other competitive advantages over other trees on the site during the establishment phase tend to retain dominant crown positions in the stand at much later stages of development; 6) The relationship of periodic basal area increment (b.a.i.) to initial basal area stocking in immature spruce-fir stands suggests that stand increment is optimized above a critical stand density; 7) The initial basal area level necessary to optimize b.a.i. appears to increase with stand age; and 8) Apparent trends from a 575-year chronosequence of Engelmann spruce-subalpine fir stand development suggests that stand basal area tends to peak, on average, between the ages of 70 and 150 years of age. Subsequently, basal area tends to gradually decline and eventually stabilize between the ages of 300 to 400 years of age. Based on these results, preliminary recommendations were proposed for the long-term silvicultural management of ESSF spruce-fir forest types. Also, the research priorities necessary for building on the results of this pilot study were identified. / Forestry, Faculty of / Graduate