摘要:

Potted grafts of old spruces (Piceaabies(L.) Karst.) were continuously fumigated with SO2(contro1, 0.05, 0.1, and 0.2 ppm) in outdoor fumigation chambers. SO2concentrations were maintained for 10 weeks from late in April till early in July 1976. CO2uptake was measured periodically under standardized laboratory conditions with an infrared gas analyzer. After fumigation, the plants remained in the nursery till November 1977. Afterwards, stem slices were taken for X-ray measurements of both ring width and wood density. An arbitrary density of 0.5 g cm−3was chosen to distinguish early wood from late wood. CO2uptake was depressed significantly before visible symptoms of injury appeared. The relative CO2uptake in the 7th to 10th week of fumigation and the number of cells in a radial file of the annual ring were well correlated. With increasing SO2concentration, the width of the annual ring decreased. The amount and density of late wood was reduced by a springtime fumigation. A distinct decline of wood production with increasing SO2concentration was also found in cases where no visible injury occurred.

ISSN:0045-5067    

DOI:10.1139/x80-001

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Variation in duff depth and weight was studied on two adjacent different aged subalpine stands in eastern Washington, U.S.A. In a 105-year-oldPinuscontortaDougl. stand, the duff depth averaged 5.46 cm as compared with 4.57 cm for a 305-year-old stand of the same habitat type. The difference between the means was not significant. The greatest duff depth (46 cm) in the younger stand was almost twice that of the older stand (26 cm), due principally to the time since last disturbance by fire. A correlation of duff depth (D; centimetres) to weight (W; tonnes per hectare) produced the equationW = 7.26 + 13.27 Dwhich hadr2 = 0.849 and SE = 7.06.

ISSN:0045-5067    

DOI:10.1139/x80-002

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Pressure–volume curves for western hemlock (Tsugaheterophylla(Raf.) Sarg.) seedlings showed roots to have lower osmotic potentials, at both full turgor and incipient plasmolysis, and lower relative water contents at incipient plasmolysis than shoots. Roots remained turgid under mild water deficit, whereas shoots lost turgor exponentially with water content. Shoots of seedlings given a 2-week drought stress had lower osmotic potentials at full turgor and incipient plasmolysis than shoots of unstressed seedlings; roots showed a similar trend.

ISSN:0045-5067    

DOI:10.1139/x80-003

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Twenty-three natural stands of trembling aspen (PopulustremuloidesMichx.) were surveyed for incidence of a canker caused byHypoxylonmammatum(Wahl.) Miller. Canker incidence ranged from 0 to 70%. Horizonal soil samples were analyzed for their chemical and physical properties, and aspen leaf lamina tissue was analyzed for nutrient concentrations. A model accounting for 92% of the variation in canker incidence was constructed, utilizing 56 measured parameters, through the use of simple- and multi-correlation statistical analyses. Highly significant negative correlations were observed between canker frequency and each of aspen cover density, soil moisture, abundance of soil mottles, soil consistence, exchangeable soil Mn, Ca, and Na, and aspen tissue concentrations of Mn, Ca, and Na. Positive correlations were observed between canker incidence and each of soil temperature, soil depth, bulk density, rooting depth, and soil fractions over 2 and 10 mm. The association between exchangeable soil nutrients and aspen tissue concentrations was highly significant (p = 0.01). It is concluded that physical and chemical parameters of the soil which related most directly to moisture comprise a system of variables which are highly related to Hypoxylon canker incidence in trembling aspen.

ISSN:0045-5067    

DOI:10.1139/x80-004

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Progenies belonging to 49 open-pollinated families of paper birch (BetulapapyriferaMarsh.) representing 13 provenances were evaluated sequentially for rate of root elongation in solutions containing only calcium nitrate and solutions containing calcium nitrate + 120 ppm aluminum. Provenances, but not families within provenances, differed significantly in both rate of root elongation and apparent response to Al. Provenance mean tolerance indices (root growth in Al solutions/root growth in non-Al solutions) varied from 0.10 to 0.37. Exposure to 120 ppm Al caused decreased concentrations of Ca and Cu in the foliage, decreased or nearly unchanged concentrations of P and Mg, and increased concentrations of Al, B, and Mn. Compared with the more tolerant provenances, intolerant provenances exhibited generally greater increases in foliar Al concentration after exposure to Al. Differential tolerance to Al will be useful in improving the performance of planted trees on Al-toxic sites.

ISSN:0045-5067    

DOI:10.1139/x80-005

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The author describes a stochastic model of forest stand rotation which can be used to determine the optimal planned rotation interval for flammable forest stands. The model can also be used to estimate the value of fire management activities in terms of the potential enhanced value of timber production. The use of the model is illustrated by applying it to a simplified case of jack pine (Pinusbanksiana, Lamb.) management.

ISSN:0045-5067    

DOI:10.1139/x80-006

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Classical growth analysis was used to examine the basis of major variation in seedling growth characteristics among and within six deciduous tree species in nursery beds. A combination of high investment in leaf area and substantial net assimilation rate accounted for the high relative growth rate ofLiriodendrontulipiferaL. andPrunusserotinaEhrh.; these species also produced the largest seedlings in the test. Final weight of fourQuercusspecies was closely associated with initial leaf area established at germination;Q.rubraL. andQ.prinusL. had the largest seedlings despite having net assimilation rates lower thanQ.albaL. andQ.ilicifoliaWangenh., the smallest seedlings in the test. Within species, relative growth rate was significantly correlated with both net assimilation rate and relative growth rate of leaf area. Leaf area partition coefficient was positively correlated with relative growth rate inL.tulipifera,P.serotina, andQ.rubrabut not inQ.alba,Q.prinus, andQ.ilicifolia.

ISSN:0045-5067    

DOI:10.1139/x80-007

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The following relationships were quantified in a mathematical computer model to predict spread and intensification of dwarf mistletoe (Arceuthobiumtsugense(Rosendahl) G. N. Jones) infection, originating from residual trees, in regeneration of western hemlock (Tsugaheterophylla(Raf.) Sarg.): distribution of dwarf mistletoe infections in residual source trees, dwarf mistletoe seed production, escape from crown and dispersal, interception of seeds by neighboring trees, distribution of seeds within crowns, development of dwarf mistletoe infections, mortality of plants, and tree crown growth. The model included options for thinning or sanitation by removal of infected residual or regeneration trees. Predictions by the model for a 10-year period did not differ significantly (p = 0.05) from results of a field plot with respect to average number of infections per tree, percentage of infections at 1-m distances from the residual tree, and percentage of infections in each quadrant centered on residual source tree. Predictions of the effects of stocking density and sanitation or thinning on infection agreed with results obtained from experiments with other tree species.

ISSN:0045-5067    

DOI:10.1139/x80-008

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Recent growth and harvest trends in commercial timberlands of the temperate zone suggest that these forests have been serving as a net sink for about 1.0 × 109to 1.2 × 109 t of carbon annually over the past 3 decades. This is 20 to 60% of the annual carbon release from combustion of fossil fuels over the period, indicating that recovery transients in temperate zone forests apparently have been partially dampening the increase in atmospheric CO2caused by fossil fuel combustion and tropical forest reduction. Net forest growth is occurring throughout the temperate zone with principal carbon sinks found in North America and in Siberia. Timber inventories for North America show an excess of growth over harvest equivalent to over 5 × 1015 g of C since the 1950. Limited data suggest that in Siberia there is a large stock of slowly growing conifers that are underexploited, forming a sink equivalent to that of North America. Reafforestation in western Europe has expanded forest area by 5% since World War II. Similar recovery may now be occurring in temperate Asia. Problems of data reliability, particularly for the U.S.S.R., and the limited basis for estimating carbon balance in entire forests, suggest a severalfold uncertainty in the carbon sink estimates.

ISSN:0045-5067    

DOI:10.1139/x80-009

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Results withPinuspalustrisMill, seedlings grown in pine bark with and withoutPisolithustinctorius((Pers.) Coker and Couch) inoculum and drenched with seven fungicides showed that ectomycorrhizal development byP.tinctoriuswas completely inhibited by Terraclor, reduced by Captan and Dexon, not affected by Mertect and Truban, and stimulated by Benlate and Banrot. In the noninfested medium, ectomycorrhizal formation by airborne fungi (mostly byThelephoraterrestrisEhr.) was greater on seedlings drenched with Benlate, Mertect, and Dexon than on the control. Terraclor and Truban reducedT.terrestrisectomycorrhizal development. Generally, fresh top and root weights were not affected by fungicide treatment. Stem diameters of seedlings treated with Captan, Dexon, Mertect, and Truban, and the control were larger in the noninfested medium than in the medium withP.tinctorius.

ISSN:0045-5067    

DOI:10.1139/x80-010

出版商:NRC Research Press    

年代:1980

数据来源: NRC