ALBERT

Description: Seedlings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) were grown in a container nursery from February to July 1988 and then exposed to three temperatures and three levels of drought stress applied factorially during mid-July to October 1988. Seedlings were retained in a shelter house until January 1989, when they were cold-stored until early May. Measurements of stomatal conductance (gs), transpiration (E), and specific leaf area (SLA) were made at the end of the treatment period in September 1988 and again after growth the following year at the end of June. Root growth capacity (RGC) was tested in early May 1989. Results were considered in conjunction with performance of other samples of the same plants that had been planted in sand beds in April 1989, where irrigation was regulated to provide three levels of moisture stress. Low temperature (13 °C) generally reduced gs and E, which were adjusted for xylem pressure potential, and SLA in all species by the time nursery treatment was completed at the end of September. No effect of nursery temperature treatment on gs and E could be detected when new needles were measured in June and July (after 9 to 12 weeks of growth), but SLA of lodgepole pine increased with nursery temperature treatment, and SLA of white spruce decreased with nursery temperature treatment. RGC was higher for the 13 °C treatment than for the 16 and 20 °C treatments. Survival of outplanted seedlings was mainly inversely related to nursery temperature. Low nursery temperature reduced gs, E, and SLA and increased RGC. SLA of planted lodgepole pine increased with level of nursery drought treatment, and severe nursery drought increased gs under stress, when measured in June. No other effects of drought were detected, although drought treatment was effective in increasing survival of planted seedlings.

Description: Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings were grown in Styroblock containers in a container nursery from February to July 1988 and then exposed to three temperatures and three levels of drought stress applied factorially during 18 July to 29 September 1988. Mean temperatures of 13, 16, and 20 °C were imposed in growth chambers, in a cooled plastic house, and in an ambient plastic house, respectively. Control, medium, and severe levels of drought stress were imposed in a series of eight cycles, resulting in mean xylem pressure potentials of −0.32, −0.50, and −0.99 MPa, respectively. Seedlings were kept in the ambient plastic house until January, when they were lifted and cold-stored until planting. Between 11 and 18 April 1989, seedlings were planted in 0.5 m deep sand beds, which provided hygric, mesic, and xeric conditions for testing all species and treatments. At the end of nursery growth, increase in nursery temperature increased height and height:diameter ratio in all species and shoot:root dry weight ratio in Douglas-fir and lodgepole pine. Increase in temperature also increased the number of seedlings with large well-formed buds in white spruce, but reduced the number in Douglas-fir. Drought stress reduced height and dry weight in all species and bud length in lodgepole pine. After 9 weeks in sand beds, low nursery temperature increased survival (19% for lodgepole pine and white spruce grown in the xeric bed), except for Douglas-fir grown in the xeric bed. Nursery drought stress also increased survival (16% for Douglas-fir and lodgepole pine in the xeric bed), but had little effect on white spruce. Low temperature and drought stress treatments that increased survival also reduced height and dry weight of lodgepole pine and white spruce after one growing season in sand beds. Survival showed significant negative correlations with height, dry weight, and height:diameter and shoot:root weight ratios. Low nursery temperature continued to affect growth after planting, increasing relative growth rate and allometric ratio (K) of Douglas-fir and decreasing K of white spruce.

Description: Seedlings from three open-pollinated aspen (Populus tremuloides Michx.) families were grown in a greenhouse with four nitrogen (N) sources, each at two N levels and three pH levels. Nitrogen sources were ammonium sulfate ((NH4)2SO4), calcium nitrate (Ca(NO3)2), ammonium nitrate (NH4NO3), and urea ((NH2)2CO); N levels were 50 and 200 mg·L1 (100-mL aliquots three times per week); and pH levels were 5, 6, and 7. Shoot dry mass and leaf area increased with pH in (NH4)2SO4 and (NH2)2CO treatments, but were greatest at pH 6 in the NH4NO3 and Ca(NO3)2 treatments as a result of a pH × N source interaction. N level was directly related to growth, net assimilation, water-use efficiency, and leaf carbon isotope ratio, while N source had no effect on these parameters. Seedlings from families 2 and 3 grew larger than seedlings from family 1, which allocated relatively more dry matter to roots. Growth of the three families interacted with soil pH so that family 1 was largest at pH 7, but families 2 and 3 were largest at pH 6. Seedling boron (B) uptake was reduced by increasing pH and by the Ca(NO3)2 fertilizer. These results were interpreted to show that although the three families seemed well adapted to all the N and pH conditions to which they were exposed, growth could be increased by selection of a fertilizer most suitable to the pH and availability of other nutrients in the soil.

Description: Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), lodgepole pine (Pinuscontorta Dougl.), and white spruce (Piceaglauca (Moench) Voss) seedlings, each represented by two seed lots, were grown in Styroblock containers in a greenhouse and plastic shelter house from February 1989 to January 1990. The seedlings were exposed to two nitrogen (N) treatments and three potassium (K) treatments arranged factorially within three drought treatments. After winter storage, seedlings from a complete set of treatments were planted into hygric, mesic, and xeric sand beds during 12–14 March. Increasing nursery drought stress increased survival of Douglas-fir and lodgepole pine after planting, and high N treatment level increased survival of lodgepole pine and white spruce. Under xeric conditions, combined nursery drought and high N treatments increased survival of lodgepole pine by 33%, indicating the importance of nursery cultural regime for stock quality. Increase in nursery drought decreased seedling size relatively little, but increase in N increased seedling size one season after planting. A positive relationship between shoot/root ratio and survival in lodgepole pine and white spruce indicated that increase in N increased both shoot growth and drought resistance over the N range investigated. Only Douglas-fir showed an interaction between drought and N treatment and a small response in both survival and dry weight to K. Root growth capacity, measured at the time of planting, showed an approximate doubling in all species due to high N treatment, and was also increased in white spruce by drought stress. Survival and root growth capacity were poorly correlated, but dry-weight growth in sand beds was well correlated with root growth capacity. Shoot dry weight and percent N in shoots measured after nursery growth were correlated with root growth capacity. Manipulation of root growth capacity by changing nursery treatment was apparently possible without altering resistance to drought stress after planting.

Description: A growth chamber experiment was conducted with Pinuscontorta Dougl. ex Loud. var. latifolia Engelm. seedlings grown in soil compacted at 0.1, 2.0, 4.0, 6.0, and 8.0 MPa pressure. Three moisture regimes were applied factorially to compaction levels by watering from above or by maintaining 2- or 10-cm water tables at the base of the 40-cm soil columns. All treatments were grown at either 22:14 °C or 26:18 °C (light:dark) for 13 weeks. Soil compaction increased bulk density, penetrometer resistance, and soil CO2 and ethylene. The presence of water tables resulted in elevated soil gravimetric water content, which rose with increased compaction and resulted in reduced penetrometer resistance and soil O2. Increased compaction was associated with decreased needle lengths, root dry weights, and net photosynthesis and increased rates of shoot respiration. Compaction had a small effect on height growth, with the tallest seedlings occurring at the greatest compaction rate. Shoot concentrations of mineral nutrients also decreased as soil compaction increased. Within the water table treatments, increased gravimetric soil water content was generally paralleled by a rise in the negative effects of compaction on growth, root/shoot dry weight ratios, and shoot mineral nutrient concentrations.

Description: The concentrations of soil CO2 and O2 at three Long-term Soil Productivity sites located in the Sub-Boreal Spruce biogeoclimatic zone of British Columbia, Canada, were monitored over several growing seasons. These sites were treated with three levels of soil compaction and three levels of organic material removal following forest harvest. Both compaction and depth had a significant effect upon soil CO2 concentrations and average values increased in response to deeper sampling and compaction. Removal of the forest floor and other organic materials had no significant effect upon soil CO2 and O2 concentrations. Mean soil CO2 concentrations varied from site to site and data collected over three growing seasons also showed that mean CO2 values in response to compaction fluctuated significantly from year to year. The high levels of soil CO2 observed in this study (up to 40 000 µ L L−1), especially in response to the compaction treatments, may have had a substantial effect upon whole plant carbon allocation as well as soil nutrition available to trees growing on the treated plots. Although mean soil O2 also decreased in response to compaction and sampling depth, these lower concentrations did not approach the levels required to influence plant growth. Key words: Soil, compaction, carbon dioxide, oxygen, long-term soil productivity

Description: Three nitrogen (N) levels and six seedling spacings were applied factorially in a randomized block design, of four replications, to coastal and interior varieties of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), Sitka spruce (Piceasitchensis (Bong.) Carr), and lodgepole pine (Pinuscontorta Dougl.) in the nursery. After growing for 2 years in the nursery, seedling dimensions, dry weights, and needle N, phosphorus (P), and potassium (K) concentrations were determined. At the same time, samples of 400 trees per treatment were planted into the forest using the nursery design. Three years after outplanting, survival and height measurements were obtained for all species and, in addition, dry weights and nutrient concentrations for the coastal Douglas-fir. Both an increase in N fertilizer and wider spacing increased 2-year-old (2–0) seedling needle percent N, except in lodgepole pine. Wider spacing also increased percent P in interior Douglas-fir and percent K in lodgepole pine. Within the highest N fertilizer level the amount of variation in needle percent N accounted for by spacing was 75% in coastal Douglas-fir, 78% in interior Douglas-fir, and 92% in Sitka spruce. Needle percent N in 2–0 coastal Douglas-fir and Sitka spruce was positively correlated with survival (r2 = 0.24 and 0.35, respectively), total height (r2 = 0.48 and 0.61, respectively), and current height growth (r2 = 0.31 and 0.51, respectively) after 3 years in the forest. The relationships of spacing to 2–0 seedling percent N, and of 2–0 seedling percent N to outplanting performance indicated that, at least for Douglas-fir and Sitka spruce, spacing influenced outplanting performance through its effect on N nutrition. During 3 years in the forest, coastal Douglas-fir trees had maintained closely similar relative growth rates (RGR) in all treatments. Consequently, relative differences in 2–0 seedling dry weight between treatments of about threefold between 0.6- and 12-cm spacing and twofold between 60 and 235 kg N/ha fertilizer levels, had been maintained. After 3 years in the forest there were no differences in nutrient concentrations between nursery N treatments, indicating that reserves available at lifting had been dissipated, but nutrient concentrations tended to decrease with wider spacing. This suggested some unidentified wide spacing effect was promoting growth and causing nutrient dilution in the tissue.

Description: Monthly sampling of stem inner bark, roots, litter, humus, and mineral soil was carried out in six 0.1-ha plots in a 47-year-old Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) stand for 1 year. Pairs of plots had received urea fertilization at the rates of 0, 224, and 448 kg nitrogen (N)/ha 4 years previously. Inner bark and roots were chemically analysed to determine concentrations of total N, soluble N, ninhydrin-positive compounds, monosubstituted guanidino amino compounds, arginine, and proline. Concentration of total N was determined in litter, humus, and mineral soil samples, and concentration of mineralizable N was also determined in humus and mineral soil.All sets of data showed an effect of season, but analysis of root soluble N, root guanidino compounds, root arginine, and litter total N were the most satisfactory for distinguishing differences in N level due to fertilizer treatments. For this purpose root sampling was best done in June and July, and litter sampling between January and May. Soluble N concentration was higher in inner bark than in roots, but arginine concentration was higher in roots than in inner bark. Root arginine concentration was high in winter and decreased to a low level in October before starting to accumulate again, suggesting it behaves as a N storage compound. Litter total N showed a decrease in concentration in July and August, followed by a recovery.

Description: Survival and growth of coastal and interior provenances of 2-0 Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), after storage for 16 weeks at different temperatures, were examined in two experiments. In the first experiment, plants of two coastal and two interior provenances were grown under three sets of environmental conditions. These provided non-hardy, partially hardy, and hardy stock of each provenance for storage at 2, −5, and −9 °C. Survival, after 8 weeks poststorage growth in the greenhouse, showed that no provenances survived storage well in a non-hardy condition, and that coastal provenances only stored well at 2 °C. Even interior provenances did not store well at −9 °C.In the second experiment plants of four coastal and four interior provenances were lifted on 10 November and again on 8 December for storage at 2 and −2 °C. Survival and stem relative growth rate measurements, made after plants had been allowed 8 weeks poststorage growth in the greenhouse, showed that 2 °C was less deleterious than −2 °C, and that coastal provenances were less tolerant of the lower temperature. Plants stored on 10 November showed better survival than those stored on 8 December, and there was no clear relationship between stem hardiness, measured by an electrical conductivity method, and survival after storage.In a third experiment, two coastal provenances of 2-0 Douglas fir were used to compare the effect of cold storage at 2 °C with exposure of heeled-in stock to open nursery conditions in satisfying the chilling requirement for bud flushing. Flushing of previously unchilled stock, which had been cold-stored for 12 weeks, occurred as rapidly as flushing of similar stock heeled-in in the open nursery for the same period.

Description: Frost hardiness of Douglas fir (Pseudotsugamenziesii Mirb. Franco.) plants was assessed by a range of freezing tests in three experiments. In experiments 1 and 2 plants were grown in different temperature regimes, under short days, for 8 weeks to induce different levels of frost hardiness. In experiment 3, plants remained in the open and were sampled on 21 occasions through one year.Comparison of stem impedance measurements made at 1 kHz, 4.5 kHz, and 1 MHz, before and after freezing tests in experiments 1 and 2, indicated survival of individual plants was well predicted by post test measurements. The postfreezing test 1 kHz/1 MHz ratio distinguished between dead and surviving plants with the smallest number of measurements. Both this ratio and 4.5 kHz impedance provided similar conclusions about treatment effects, which agreed satisfactorily with conclusions from survival data. Impedance ratios of 1 kHz/1 MHz measured in stems after freezing tests accurately predicted survival in experiment 3. Seasonal changes in ratio, determined after freezing to a particular temperature, paralleled seasonal change in plant frost hardiness and was significantly correlated with exposure to cold during 14 days prior to measurement.