摘要:

Twenty years after planting, X-ray densitometry and immersion were used to determine the relative density of wood from 28 white spruce populations of the Great Lakes – St. Lawrence forest region. The results showed the same pattern of radial variation in all populations. Wood density decreases for the first few years of growth, then stabilizes for a time, then increases slowly, but steadily. The relative density of wood from white spruce has a slight, negative correlation with the width of the annual growth rings, at either the individual or the population level. However, some populations and individuals do deviate from this trend. Though the populations showed some statistically significant differences in relative density, analysis of variance showed that 85 to 90% was attributable to differences among trees within the same population. This study confirmed the desirability of using relative density as the basis for making mass selections within fast-growing white spruce populations to genetically improve the genetic quality of wood.

ISSN:0045-5067    

DOI:10.1139/x90-018

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Field experiments of the range-wide black spruce (Piceamariana(Mill.) B.S.P.) provenance study were established between 1973 and 1977 through the cooperation of several organizations in the United States and Canada from the Atlantic Coast to Alberta. This study evaluates performance at 11 or 15 years from seed in 29 locations divided into 8 regional clusters of 2 to 10 experiments each. Analytical methods include correlations of height and survival with geographic and climatic variables, analyses of variance, and polynomial regressions followed by contour plotting. Best height was obtained in the Great Lakes States and in other temperate regions, and best survival in Newfoundland and some temperate regions with long growing seasons. Correlations between height and survival were positive and significant only in 10 locations, 8 of which were located in temperate regions. In many locations in boreal regions, correlations with latitude or climatic variables at the place of seed origin and height have opposite signs of correlations with survival, indicating difficulties when simultaneously selecting for good height and high survival in cold climates. Contour plots from the regressions demonstrate a similar trend by showing good pattern overlap of height and survival primarily in mild coastal (Newfoundland) or temperate continental climates (southern Quebec and Ontario, Great Lakes States). There is evidence that provenance differences are still developing and changes in rank are taking place, and therefore additional assessments are required in the future.

ISSN:0045-5067    

DOI:10.1139/x90-019

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Postfertilization patterns of fascicle weight and foliar nutrient concentration can diagnose nutrient limitation and stem growth response of coniferous species that have one annual needle flush. We tested this approach on loblolly pine (PinustaedaL.), a species with several annual growth flushes, by using only foliage from the first annual growth flush following fertilization. We analyzed the responses of foliage weight and nutrient concentrations to a 4 × 3 factorial application of nitrogen (0–336 kg/ha) and phosphorus (0–56 kg/ha), and used the results to predict growth limitation. Nitrogen fertilization increased fascicle weight and foliar nitrogen concentration in eight of the nine study sites, implying nitrogen limitation. Phosphorus fertilization increased fascicle weight and foliar phosphorus concentration in three sites, implying phosphorus limitation. Two- and 4-year diameter growth response data generally supported these predictions. Diameter growth responded to nitrogen or nitrogen plus phosphorus in all predicted sites, but the technique failed to identify phosphorus limitation in one site and nitrogen plus phosphorus limitation in another. Growth response predictions based on initial foliar nutrient concentrations or foliar responses to fertilization were equally accurate. The greater expense of using the foliar response method may not be justified in operational assessments of forest nutrition.

ISSN:0045-5067    

DOI:10.1139/x90-020

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The seasonal patterns of carbon gain and allocation were examined inPinustaedaL. seedlings grown under field conditions. To investigate how ozone stress may influence whole-plant carbon budgets over the growing season, the seedlings were grown in either ambient air or air enriched with ozone at twice-ambient levels. On five sampling dates during the 1987 growing season, seedlings were labeled with14CO2, and whole-plant carbon budgets were constructed. Rate of assimilation of CO2varied by a factor of 2 during the growing season, with a late spring maximum during the first growth flush. Respiratory losses were highest in the spring and then declined sharply during the summer when photosynthate allocation to the foliage increased rapidly. A second major shift in the carbon budget occurred in the autumn when allocation to the fine roots increased at the expense of the foliage. The proportion of photosynthate allocated to coarse roots and stems varied only slightly over the growing season. Allocation to any plant component was highest when growth of that component was at a maximum. No statistically significant effects of elevated ozone on either carbon gain or photosynthate allocation were detected at any specific time during the growing season. However, seedlings grown at twice-ambient ozone levels consistently exhibited the following trends: (i) lower rates of CO2assimilation, (ii) greater allocation of photosynthate to respiration, and (iii) corresponding reduction in photosynthate allocation to fine roots. An individual-fascicle14C-labeling technique was found to reflect the seasonal patterns of carbon import and export by foliage and thus may serve as an acceptable surrogate for whole-tree tagging. The pronounced seasonality of the carbon budgets inP.taedain conjunction with a pattern of ozone effects on carbon assimilation and photosynthate allocation suggests that whole-plant carbon budgets are sensitive and biologically meaningful indicators of seedlings' responses to anthropogenic changes in atmospheric chemistry.

ISSN:0045-5067    

DOI:10.1139/x90-021

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The comandra blister rust parasite (CronartiumcomandraePk.) causes a serious canker disease of lodgepole pine (PinuscontortaDougl. ex Loud. ssp.latifolia(Engelm.) Critch.) in the central Rocky Mountains. The expansion, longevity, and distribution of comandra blister rust cankers were studied by annual monitoring, reconstructing canker histories, and random sampling. In saplings, infections occur throughout the lower 80% of the crown; and branch cankers expand toward the bole at 2.5 cm•year−1, regardless of temperature, age, position, tree size, vigor, or susceptibility to infection. The proportion of branch cankers that develop into stem cankers decreases logistically both with distance from infection site to bole and with time since infection. Fewer than 50% of branch cankers that are farther than 20 cm from the bole or more than 8 years old are expected to establish stem cankers. The proportion of branch cankers that become stem cankers decreases with distance more rapidly for comandra blister rust than for other stem rusts. The mean height of stem cankers increases with total tree height, but cankers are uncommon at the top of the crown and low on the trunk of larger trees. The number of years for a canker to girdle its host equals the diameter of the stem at the center of the canker measured in centimetres. Because girdling cankers develop infrequently, slowly, and predictably, potential losses from comandra blister rust can be reduced by timely and appropriate removal of damaged trees.

ISSN:0045-5067    

DOI:10.1139/x90-022

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Ten forest litters with decomposition state varying from 16.6 to 100% weight remaining were partitioned into sub-samples; each subsample was analyzed for proximate carbon fractions using one of two chemical analysis procedures (forage fiber and forest products analyses). Proximate carbon fractions from the simpler forage fiber techniques accurately estimated extractives, cellulose, lignin, and acid-hydrolyzed carbohydrates (R2 > 0.83) determined by the more complex forest products analyses. Decomposition state accounted for most of the residual variance and significantly improved predictive equations for lignin and extractives. The relationship between proximate carbon fractions from the different techniques also varied somewhat among wood, hardwood leaves, and conifer leaves; however, variations were minor relative to the overall trend. Equations developed can be used to extend data availability for developing and validating decomposition models.

ISSN:0045-5067    

DOI:10.1139/x90-023

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Differences between linear program based timber harvest schedules that use decision variables based on stand types (homogeneous but generally noncontiguous areas) and management units (generally heterogeneous but contiguous areas) were investigated. It was proposed that (i) optimal harvest schedules identified using stand type decision variables should have larger present net value objective function values than those identified using models with management unit decision variables, (ii) optimal present net value objective function values in management unit models should decline as management unit size is increased, and (iii) as the number of management choices increases, differences between stand type and management unit optimal present net values should decrease. The propositions were tested using 48 linear programming timber harvest scheduling models constructed for the University of California's Blodgett Forest Experiment Station. These models, which form 12 model groups, differ in the numbers and type of prescriptions considered for existing or regenerated stands, and harvest flow or ending inventory policies. The results generally supported the propositions and indicate that the number of management choices considered in the timber harvest scheduling model is probably a more important factor influencing the optimal harvest schedules than is land classification.

ISSN:0045-5067    

DOI:10.1139/x90-024

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Tree diameter, height, form, and number of stem defects were recorded in 26-year-old plantations of Sitka spruce,Piceasitchensis(Bong.) Carr., established at three initial spacings (2.74 × 2.74, 3.66 × 3.66, and 4.57 × 4.57 m). These plantations were heavily attacked by the Sitka spruce weevil,PissodesstrobiPeck, from an early age. Denser plantations sustained a lower intensity of attack than the more open plantations. Although the three spacings had similar average number of stem defects per tree, trees in the close spacing had a significantly higher frequency of trees of good form relative to the more open plantations. It was concluded that trees planted at close spacing had lower levels of weevil damage. As a management regime, it is recommended that Sitka spruce plantations be started at close spacing (2.74 × 2.74 m) and precommercially thinned at age 25. By this age trees will average about 19 cm in dbh and 12 m in height, thus ensuring a first log of good quality.

ISSN:0045-5067    

DOI:10.1139/x90-025

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

As part of a study to determine the parameters for effective scarification and promotion of black spruce natural regeneration, aninvitroexperiment was conducted to assess growth and rooting ability in sandy soils of four bulk densities (0.85, 1.05, 1.25, and 1.45 g cm−3). The experiment included seeds from two origins, one representative of a well-drained upland site and the other, of a poorly drained lowland site. Results show that black spruce successfully established itself in all bulk densities under study. Shoot growth was best in bulk density 1.25 g cm−3with the seeds of upland origin. It was also good for seeds of both origins in the 0.85 and 1.05 g cm−3soils. However, seedlings established in the soil compacted to 1.45 g cm−3showed reduced growth. Bulk densities of 0.85 and 1.05 g cm−3favored deep root penetration, whereas densities of 1.25 and 1.45 g cm−3restricted rooting. As a whole, upland seedlings developed better rooting than lowland seedlings, indicating that the selected sites of origin could represent two distinct ecotypes. As to allocation between shoots and roots, an interaction was found between bulk density and seed origin.

ISSN:0045-5067    

DOI:10.1139/x90-026

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The fuel structure and flammability of subalpine fir (Abieslasiocarpa(Hook.) Nutt.) stands were studied to determine the relationship between these forests and fire. It has long been known that subalpine fir forests burn catastrophically, but the contributions of fuel structure and fuel moisture to this pattern of burning have been relatively unstudied. This investigation discovered two relationships. First, over twice as much fuel in subalpine fir forests accumulated around the bases of the fir trees than in the forest as a whole, and the many dead branches on the lower trunks may allow fire to travel up into the canopy. Second, the fuels in subalpine fir forests were more flammable at the end of the summer than at the beginning, and maximum flammability was achieved in early August when the fuel moisture was between 16 and 22%. We also found that the fuel structure of subalpine fir was different from that of fire-stable ponderosa pine (PinusponderosaLaws.) forests. The fuel around the bases of the trees in ponderosa pine forests was not significantly different from that in the entire forest, and there were few branches on the lower trunks.

ISSN:0045-5067    

DOI:10.1139/x90-027

出版商:NRC Research Press    

年代:1990

数据来源: NRC