This study was undertaken to compare the overstory above-ground biomass, net primary production, and nutrient cycle in three common types of subalpine coastal forests near Vancouver, B.C. Canada. Twelve sample plots, representing three plant associations of different moisture regime, were established along an elevation transect. The following parameters were determined on each plot: overstory litterfall biomass and its macronutrient content, overstory throughfall volume and its macronutrient content, above-ground tree biomass and its macronutrient content, tree bole wood increment, annual net primary production and its macronutrient content, mean depth of forest floor and its biomass. The quantity of macronutrients supplied in incident precipitation was measured in three forest openings in the vicinity of the sample plots. Litterfall was sampled for 24 months, while throughfall and incident precipitation were sampled during the summers of three consecutive years. Diameter increment for the last 20 years was measured on increment cores obtained from 95 randomly selected trees. Increment of tree boles was calculated from allometric volume equations and combined with data on litter production to provide the estimate of net primary production. Distribution of biomass and macronutrients in the above-ground tree layer was calculated by logarithmic equations prepared in a preliminary study. Sample plots ranged in elevation from 1250 to 1450 m. Tree cover consisted of mountain hemlock and Pacific silver fir in various proportions with some yellow-cedar at the top and some western hemlock at the bottom of the elevation transect. Mean age of trees on the sample plots ranged from 295 to 440 years. The above-ground tree standing biomass on the sample plots was 389-731 t/ha, with the largest volumes on the mesic sites. The annual net primary production was 1.77-3.35 t/ha. The biomass of overstory above-ground litterfall was 1.48-3.02 t/(ha*a); the amount of macronutrients in litterfall was 24-41 kg/(ha*a). The largest litter production was on mesic sites. There was a considerable amount of epiphytic lichens in the litterfall (71-426 kg//(ha*a)). The amount of nitrogen in incident precipitation was greater than in throughfall, indicating that the tree canopy extracted nitrogen from rainwater. More than 1 kg/ha of nitrogen was extracted from rainwater during the summer sampling period. In contrast, up to 3 kg/ha of potassium, 1 kg/ha of calcium and 10 kg/ha of sulphur were leached from the tree canopy during the 13 weeks summer sampling period. It is possible that the high value for sulphur reflects the presence of a pulpmill about 20 km southwest of the study area. The results of the study were used to test the hypothesis that differences in phytosociological characteristics occurring on a topographic sequence along relatively short elevation transects are accompanied by sufficiently large changes in patterns of ecosystem function to distinguish these sites on a functional basis. Analysis of the data supported this hypo thesis. / Forestry, Faculty of / Graduate

Forest road building and timber harvesting operations have been recognized as principal causes of forest soil degradation. These activities can result in accelerated soil erosion, excessive scarification, and/or increased soil density, which may adversely affect site productivity. A study of landing areas emphasize the deficiencies in current rehabilitation guidelines Increased soil density on both summer and winter landings was still evident at 30 cm and the soil nutrient quality was poor. Two field tests of a green fallow system on subsoil materials exposed by erosion and landing construction proved successful in building site nutrient capital to acceptable levels. Seedling growth response to green fallow crop establishment in the coastal study verified these findings. A benefit-cost analysis of several forest soil rehabilitation scenarios demonstrated the importance of including secondary and intangible factors. From a pecuniary standpoint, based on primary benefits and costs, rehabilitation was economically feasible only when a low social discount rate (2%) and an optimistic stumpage increase projection (3% per year), were used. A discussion of some secondary and intangible benefits (i.e., harvesting rates, employment, government revenues, erosion control, and industry image) stresses the need for effective forest soil rehabilitation. / 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

The sustained-yield policy presently practiced in British Columbia necessitates intensive management of forest land especially in the coastal region of the province. Soils, their nature and distribution, provide an ideal framework for a successful implementation of such management. A mapping system encompassing geology and soil and providing units interpretable for forestry practices was developed for the coastal forested lands of British Columbia. The system contains several steps of mappings corresponding to different intensities or levels of abstraction. These levels are: 1. Bedrock geology, 2. Surficial geology, 3. Geologic units, 4. Geologic unit - drainage classes, 5. Soil associations, and 6. Soil catenas. Mapping employs air-photo interpretation extensively and can be directly undertaken at any desired level for inventory of interpretation purposes. Grouping of units can also be made from any level of mapping. Maps showing the distribution of bedrock types, surficial materials and soils were prepared. Vancouver volcanics, Coastal intrusives and Cretaceous sandstones are the main bedrock formations. The surficial materials encompass the inter-glacial, glacial, post glacial and recent deposits, and consist of glacial tills, glaciofluvial, alluvial and marine sediments. The soils encountered represent the Podzolic, Brunisolic, Regosolic, Gleysolic and Organic Orders. The area is comprised of primarily Douglas-fir plantation, 20 to 30 years of age. Studies involving the soil-stand growth relationship were undertaken on the well drained soils developed on the major surficial materials. Morphological, physical, chemical and minera1ogica1 characteristics of soils and the growth statistics of stands were determined. The growth performance of Douglas-fir varied with the kind of soil. Growth was best on soils developed from marine clay. Soils developed from stony outwash exhibited the slowest growth and lowest productivity. Till soils had productivity between these two extremes. The textural components of soil (coarse sand, medium sand, total sand, total silt, coarse clay, fine clay and total clay), were correlated to growth. With respect to chemical nutrients, organic matter, calcium and magnesium, phosphorus and zinc appeared to be important factors. The soil moisture retention characteristics such as field capacity and available water showed correlation with growth. The relationship between the growth and soil characteristics became more apparent as stand age advanced. Interpretation of soil series and mapping units at different levels was carried out for: productivity for Douglas-fir, species suitability, logging hazard, slash burning hazard, natural regeneration probabi1ity, brush hazard, browsing hazard, thinning prescription, fertilizer recommendation, road construction suitability, and erosion. Two groupings, potential productivity and thinning recommendation for Douglas-fir, were undertaken. The study indicated that knowledge of soils and their distribution are prerequisite to the operational and economical management of forest and soil resources. Consequently, a classification scheme such as the one presented is the first and essential step towards the intensive management of the coastal forested lands in British Columbia. / Land and Food Systems, Faculty of / Folded map and table in back pocket. / Graduate