摘要:

A field study examined the effects of competing vegetation on the moisture and nutrient status of 5-year-old loblolly pines (PinustaedaL.). Similar experiments were conducted on a Piedmont site and a Coastal Plain site using individual pines as experimental units. Predawn measurements of xylem pressure potential were made using detached needle fascicles, and nutrient concentrations in soil and foliage samples were determined monthly. This study was conducted during the 3rd year of a relatively dry 3-year period. On the Piedmont site, elimination of all competing vegetation within 1.5 m of the pines significantly lowered moisture stress when compared with the no-elimination treatment; on the Coastal Plainee site, differences were significant on only half of the assay dates. Removing only arborescent vegetation on the Piedmont site reduced pine water stress one-half as much as removing all vegetation, but on the Coastal Plain site this reduction was about two-thirds of that found following removal of all vegetation. As drought length increased, stress increased, regardless of treatment. Higher levels of competing vegetation significantly reduced available potassium, calcium, magnesium, and manganese concentrations in the loamy sand of the Coastal Plain site, but only potassium was reduced on the Piedmont. None of the treatments significantly affected foliar nutrients at either site.

ISSN:0045-5067    

DOI:10.1139/x84-001

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A comparative study on plantlet formation in black (Piceamariana(Mill.) B.S.P.) and white (Piceaglauca(Moench) Voss) spruce led to the development of similar in vitro systems. Buds were induced on epicotyl explants on Schenk and Hildebrandt's mineral salts containing sucrose and equimolar concentrations of benzylaminopurine and 6-(γγ-dimethylallylamino)-purine. Transfer to cytokinin-free medium allowed for secondary, shoot formation. Shoot elongation and development required a medium with reduced sucrose and containing conifer-derived charcoal. Preparation for rooting involved further culture in charcoal-free medium. For rooting, shoots were dipped in a sterilized rooting powder containing indolebutyric acid and placed in sterile vermiculite containing half-strength mineral salts, sucrose, and charcoal. Roots could also be formed under nonsterile conditions. Shoot formation had a higher optimum temperature and longer photoperiod requirements than rooting. The above sequence of manipulations can produce ca. 40 plantlets per seed within 170 days in culture.

ISSN:0045-5067    

DOI:10.1139/x84-002

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Effects of inbreeding in a natural population of black spruce (Piceamariana(Mill.) B.S.P.) were studied using progenies from self-, open-bag, open, and pollen-mix pollinations. Self-pollination resulted in significant reductions in seed set and early height. The numbers of embryonic lethals were estimated comparatively by using two different models. Based on full seed data, the population carried an average genetic load of five to seven embryonic lethal equivalents per zygote. The total number of lethal equivalents, acting from the time of pollination through age 6 years, ranged from about six to eight. The role of polyembryony in maintaining heterozygosity is discussed. Significant differences among female parents with respect to seed weight, percent germination, and 2- and 6-year heights indicated substantial variation owing to additive genetic and maternal effects. Relative self-fertility in the species, although generally high, varied widely among parents.

ISSN:0045-5067    

DOI:10.1139/x84-003

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The significance of two promotional elements (presentation and product) in explaining the variations in the attitudes towards timber species are examined in this paper. In measuring such attitudes, the original Fishbein model is used and the attitudes are expressed as a function of five pretested attributes (beauty, durability, smoothness of texture, coldness, and modernity). A detailed ANOVA showed that variations in attitudes were explained mainly by the type of product and to a lesser extent by the two-way interactions of product and the species used to produce the product while the type of presentation was not significant. It was found that the respondents had certain preconceived ideas about the properties of individual species and these ideas were directly related to products and (or) applications traditionally associated with each species. Finally, the multidimensional model of "utilities," UNICON was applied to the data. Two analyses were performed, one on the utilities of the different products, species, and types of presentation and one on the utilities of the different attributes tested. The findings corroborated those of the analysis of variance. Very different utility factors were attached to different combinations of products made out of different species while the type of presentation was not significant. Therefore, for promotional purposes a very detailed and segmented approach is needed and this will depend on the particular product and the species used and consequently different attributes must be emphasised and promoted.

ISSN:0045-5067    

DOI:10.1139/x84-004

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Strobili distribution on crowns of 8- and 9-year-old white spruce (Piceaglauca(Moench) Voss) was evaluated and modified by gibberellin A4/7(GA4/7) applied as a foliar spray to branches in the transitional (female → male) zone and strictly male zone. Treatment with GA4/7increased female strobili production 6.2-fold and male strobili production 2.4-fold on branches in the transitional zone. On male zone branches treated with GA4/7, female strobili were induced and male strobili production increased sixfold.

ISSN:0045-5067    

DOI:10.1139/x84-005

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Reduced levels of root activity were associated with winter injury to shoots of 1-year-old black spruce (Piceamariana(Mill.) B.S.P.) container seedlings.

ISSN:0045-5067    

DOI:10.1139/x84-006

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Jack pine (PinusbanksianaLamb.) seedlings were grown for 20 weeks in a peat–vermiculite medium inoculated with solid carrier mycelial inoculum. The low fertilizer levels used resulted in seedling sizes below standard for outplanting but permitted mycorrhizal development by 9 of the 12 fungi tested. Greater than 90% of the short roots were infected when seedlings were inoculated withThelephoraterrestrisEhrhart ex Fr.,LaccariaproximoBoudier,Hebelomasp., or E strain. About half the short roots were infected whenCenococcumgeophilumFr.,Pisolithustinctorius(Pers.) Coker & Couch, andAstraeushygrometricus(Pers.) Morgan were used. Thirty-two and 17% of the short roots were infected byLactariusparadoxusBeardslee & Burlingham andSphaerosporellabrunnea(Alb. & Schw. ex Fr.) Svrcek & Kubicka, respectively. Inoculation withAmphinemabyssoides(Fr.) J. Erikss.,HydnumimbricatumL. ex Fr., andTricholomaflavovirens(Pers. ex Fr.) Lundell resulted in no infection.

ISSN:0045-5067    

DOI:10.1139/x84-007

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The effect of vines on diameter growth ofLiquidambarstyracifluaL. (sweetgum) in a 40-year-old abandoned field was measured by vine removal experiments. Removal of vines from the trunk, branches, and ground had a significant positive effect on growth during each of the 4 years of the study, but removal of vines from only the trunk and branches did not produce a significant increase in growth. The data suggest that vines influence forest production by competing with trees even after trces have grown tall enough to avoid direct physical suppression.

ISSN:0045-5067    

DOI:10.1139/x84-008

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A horizontal point cruise for basal area was conducted to develop the functional relationship between measurement error and the time allowed to measure a prism point. With this information, it was then possible to design for subsequent inventories a survey that was optimal in respect to the total survey time, given a desired level of precision of the estimated mean basal area. It was shown that using traditional techniques for estimating sample size will not provide an optimal design, if measurement error does exist and is controllable. When designing a forest survey, a great deal can be gained by explicitly accounting for measurement error, as well as sampling error.

ISSN:0045-5067    

DOI:10.1139/x84-009

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

This study examined the 10-year effects of a light (20% basal area removed) low thinning and urea fertilization (336 kg N/ha) on a 45-year-oldPinusbanksianaLamb. stand. Thinning had no effect other than salvaging potential mortality, while fertilization resulted in an average annual gross volume growth response of about 2 m3 ha−1year−1. Volume growth response to fertilization was greatest in the largest diameter trees, and continued until 10 years after treatment. Growth response did not begin until the second growing season after treatment. There were indications that fertilization had positive effects on form factor.

ISSN:0045-5067    

DOI:10.1139/x84-010

出版商:NRC Research Press    

年代:1984

数据来源: NRC