摘要:

The level of chloroplast DNA (cpDNA) diversity was estimated among individuals, populations, and geographic regions of Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco) in British Columbia by analyzing restriction fragment length polymorphisms (RFLP) from 18 populations covering the three geographic regions (coast, transition zone, and interior). Four sets of pooled probes, consisting of four to eight cpDNA clones from lodgepole pine (PinuscontortaDougl. ex Loud.), were used as hybridization probes for RFLP analysis. Thirty cpDNA restriction fragments out of a total of 175 observed fragments were detected to be polymorphic in all four sets of hybridization probes. Sixteen haplotypes were characterized among all of the Douglas-fir populations. The transition region showed the highest level of total genetic diversity (0.853) and genetic diversity within populations (0.762) of the three regions. The highest degree of population differentiation was found in the interior region (0.193). A higher proportion of the genetic diversity was allocated within populations than among populations in all three regions. Only 11–19% (mean 14.6%) of the total genetic diversity within geographic regions is due to interpopulation genetic diversities. The distribution of cpDNA diversity in sampled B.C. Douglas-fir is concordant with a typical pattern for long-lived woody species as observed in allozyme studies.

ISSN:0045-5067    

DOI:10.1139/x94-236

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Four species of boreal forest conifers share a similar southern limit of natural distribution in the three Prairie Provinces of western Canada. The southern boundaries of boreal forest and aspen parkland were compared with geographic patterns of several climate variables to provide a preliminary assessment of how global climate change could affect forest distribution in the future. Forest zonation corresponded most closely with climatic moisture regimes (annual precipitation minus potential evaporation). In contrast, thermal characteristics of climate (mean July and annual temperature, growing degree-days) showed an inconsistent relationship with forest zonation. It is postulated that moisture limitations prevent conifer regeneration south of the present limit of natural distribution. Alternatively, the more arid climates south of the boreal forest may have promoted higher fire frequencies historically, thus preventing conifers from achieving sufficient longevity to regenerate. The driest areas of boreal forest in the region occur at low elevations in west-central Manitoba, throughout Saskatchewan and Alberta, and the southwestern Mackenzie District, Northwest Territories; these areas may be most vulnerable to increased climatic dryness. Climatically induced losses of forest cover from these low-elevation areas could eventually lead to the fragmentation of the boreal forest in western Canada.

ISSN:0045-5067    

DOI:10.1139/x94-237

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The growth and yield of jack pine (PinusbanksianaLamb.) was studied in even-aged stands of three types: pure jack pine, jack pine mixed with paper birch (BetulapapyriferaMarsh.), and jack pine mixed with trembling aspen (PopulustremuloidesMichx.) growing on moderately well-drained glaciolacustrine clay soils in the southern tip of the Clay Belt of northwestern Quebec. Site index, average DBH, and average height of jack pine, and the availability of nutrients in the forest floor were compared among stand types. No differences were found in the height growth of jack pine among stand types. However, diameters of jack pine in mixtures with paper birch were significantly greater than in either pure stands or in mixtures with aspen despite the fact that both mixed stand types showed higher forest floor pH and greater concentrations of exchangeable calcium and magnesium than the pure stands. These results, together with the pattern of height growth of the three species, suggest that the beneficial effect of paper birch on the diameter growth of jack pine is caused mainly by a reduction in the competition for light among individual jack pine trees. The silvicultural implications of the results are discussed.

ISSN:0045-5067    

DOI:10.1139/x94-238

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

To characterize as early as possible the status of flowering differentiation in Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco), the variation of amino acids and polyamines was studied in the shoots during the period covering flowering initiation (between 4 and 10 weeks after bud burst). These compounds were also quantified in sexual and vegetative buds. The qualitative and quantitative effects of treatments susceptible to stimulate flowering (application of gibberellins (GA) and (or) calcium nitrate (N)) were observed in the shoots. Only N and N + GA treated trees flowered, the flowering being especially abundant for trees treated by N + GA. Arginine and proline were generally more abundant in sexual buds than in vegetative ones and in the shoots of flowering plants than in the control shoots. Sexual buds were characterized by a ratio of putrescine/(spermidine + spermine) about two times lower than in vegetative buds, mainly owing to a lower level in putrescine. The accumulation of polyamines in the shoots accompanied bud sexualization, which suggests that polyamines may constitute potential markers, probably rather early ones (4–6 weeks after bud burst), of floral initiation in Douglas-fir. This possibility is discussed.

ISSN:0045-5067    

DOI:10.1139/x94-239

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The objectives of this study were to (i) determine the extent of genetic variation and genetic control of cambial phenology in coastal Douglas-fir (Pseudotsugamenziesiivar.menziesii(Mirb.) Franco), (ii) assess the degree to which cambial phenology is genetically related to bud-burst timing, (iii) examine genetic relationships between cambial phenology and growth traits, and (iv) evaluate the potential for indirectly altering cambial phenology in breeding programs when selection is for stem volume. Dates of diameter-growth initiation and cessation, and duration of diameter growth (i.e., cambial phenology traits), as well as diameter increment for a single growing season (1987, at the age of 15 years from seed), were estimated from cumulative diameter growth curves of individual trees of 60 open-pollinated families growing in one plantation. Data on stem height and diameter (DBH), and date of bud burst in 1987 were also collected. Dates of diameter-growth initiation and cessation differed significantly among families, but had lower estimated individual heritabilities (≤0.23) than date of bud burst (0.87). Weak genetic correlations between date of bud burst and dates of diameter-growth initiation and cessation (range −0.09 to 0.26) indicate that timing of diameter growth cannot be reliably predicted from observations on the more easily measured bud burst. Cambial phenology traits were weakly correlated with 1987 diameter increment and moderately correlated with 15-year DBH and volume. Selection of parents in this study for stem volume at age 15 and subsequent crosses among them, would be expected to lead to earlier initiation of diameter growth in the offspring, and possibly later cessation as well. The practical implications of these indirect responses in terms of increased risk of frost damage are unclear, since projected changes are small (i.e., a few days).

ISSN:0045-5067    

DOI:10.1139/x94-240

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

To better understand the genetic control of wood formation in coastal Douglas-fir (Pseudotsugamenziesiivar.menziesii(Mirb.) Franco), and to assess the potential impact of selecting for increased wood density on adaptation of trees, genetic relationships of wood density, and its components, with cambial growth rhythm traits were examined in a 15-year-old progeny test. Timing of diameter growth during the 1987 growing season was available from an earlier study, and wood formation traits were estimated by X-ray densitometry of increment core samples. Wood formation traits were under weak genetic control. Lengths of earlywood and latewood formation were mostly determined by the timing of latewood transition. Overall core density was negatively correlated with the dates of cambial growth initiation (rA = −0.41) and latewood transition (rA = −0.62), and positively correlated with the date of cambial growth cessation (rA = 0.40). As a result of these relationships, higher wood density was associated with a longer duration of cambial growth (rA = 0.67) and a slower rate of wood formation (rA = −0.37). All density components showed similar relationships with cambial phenology and wood formation traits. Selection for increased wood density is expected to cause only a slight extension of the cambial growth period, but it would also cause an earlier transition to latewood formation, negatively affecting growth rate.

ISSN:0045-5067    

DOI:10.1139/x94-241

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Foliar injury symptoms and stem diameter growth were measured on well-watered and drought-stressed ponderosa pine (PinusponderosaDougl. ex Laws.) seedlings at the end of each of 3 years of exposure to three levels of ozone: charcoal-filtered air, nonfiltered air, and nonfiltered air plus 1.5 times ambient ozone. Ozone-injury indices were constructed by adding percent chlorotic mottle and percent necrosis for each needle age-class. Percent necrosis was weighted from 1 to 5 times to construct different indices. Seedlings grown in nonfiltered air plus 1.5 times ambient ozone developed severe foliar injury after 2 years of exposure and were the only seedlings with significant reductions in radial growth after three seasons of exposure to a mean seasonal ozone concentration of 88 ppb. Foliage that had developed >30% chlorotic mottle by September of the 2nd year had abscised by September of the following year. Reduction in radial growth was significantly correlated with amount of foliar injury in well-watered trees, and the best-fit regression equation occurred when percent necrosis was weighted by a factor of 4. Regressions between foliar-injury indices and radial growth in drought-stressed trees were not significant, nor were regressions between radial growth and foliar injury among well-watered trees with only 1 year of premature needle abscission. The lowR2(0.30) between foliar injury and radial growth in well-watered trees and the lack of a significant regression in drought-stressed trees suggest that detection of reductions in stem diameter growth of ponderosa pine in the field in response to ozone injury could be difficult, except for severely injured trees with fewer than 2 years of foliar retention.

ISSN:0045-5067    

DOI:10.1139/x94-242

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The export of mass and nutrients associated with the formation of fungal sporocarps during the first 7 years of decomposition of logs of four conifer species (AbiesamabilisDougl. ex Forbes,Pseudotsugamenziesii(Mirb.) Franco,ThujaplicataD. Don, andTsugaheterophylla(Raf.) Sarg.) was investigated in western Oregon. Abundance of the most common fungal species,Naematolomacapnoides(Fr.:Fr.) P. Kumm, differed significantly with log species; the fungus was most abundant onAbiesand least abundant onThuja. Fungi increased concentrations of N, K, and P over those found in associated logs by as much as 38, 115, and 136 times, respectively. Thus, a fair proportion of the initial N (0.9–2.9%), K (1.8–4.5%), and P (1.9–6.6%) was transported out of logs via sporocarps at a time when immobilization would have been predicted from critical element ratios (e.g., C/N).

ISSN:0045-5067    

DOI:10.1139/x94-243

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Systems theory can provide a useful conceptual framework for the development of forest growth models. Modelling approaches are examined and compared, based on the state-space description of dynamic systems. This viewpoint is used also to discuss the principles behind height-based site indices and possible extensions, and problems of statistical parameter estimation. Four main kinds of estimation methods for dynamic systems can be distinguished. A multidimensional generalization of the Richards model illustrates many of the ideas.

ISSN:0045-5067    

DOI:10.1139/x94-244

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Changes in tree form and taper over time, as affected by changes in tree, stand, and site factors for interior lodgepole pine (Pinuscontortavar.latifoliaEngelm.) were investigated using detailed stem analysis data from interior British Columbia. It was found that tree shape and taper change along the stem at one time and over time with changes in tree and stand factors, particularly the diameter at breast height to total tree height ratio, crown length, and crown ratio, and with predicted quadratic mean diameter at age 50 years, a stand density measure. At young ages, the trees were parabolic in shape from ground to top. However, as they increased in size over time, different portions of the stem took different shapes because of unequal growth in diameter along the stem. Changes in tree shape and taper over time were closely related to the crown size, which is related to stand density.

ISSN:0045-5067    

DOI:10.1139/x94-245

出版商:NRC Research Press    

年代:1994

数据来源: NRC