摘要:

The tarnished plant bug(Lygus rugulipennis)and occasionallyL. punctatuswere found to feed on pine seedlings in central Finland. Both the nymphs and adults ofLygusbugs injured the apical meristem of the seedlings. This led to the death of the apex, and the opening of the lateral buds, resulting in a seedling with multiple leaders.L. rugulipennismay also oviposit on pine seedlings and the development from egg to adult on pine alone is possible. In laboratory experiments it was shown that the main factor in the apical meristem injury is the mechanical damage caused by the bug's stylet. The feeding damage and artificial mechanical damage caused by needles to the apical meristem of pine seedlings resulted in increased numbers of multiple‐leader seedlings and reduced shoot length and dry weight of the shoot and root.

ISSN:0282-7581    

DOI:10.1080/02827588609382426

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The attack density and brood production ofTomicus piniperda(L.) (Col., Scolytidae) were recorded on stems ofPinus sylvestrisL. felled in southern, central, and northern Sweden before, during, and after the spring flight period in 1977 and 1978. The study sites were adjacent to stands clear‐felled during the last or the previous winter. The attack density (i.e., the number of egg galleries per m2inner bark area) varied considerably between localities and years. At all sites high attack densities were recorded in trees felled before or soon after the flight commencement, whereas few attacks occurred in trees felled in late May or later. The availability of brood material did not affect the seasonal attack pattern in any consistent way. The brood production varied from zero to more than 900 individuals per m2.

ISSN:0282-7581    

DOI:10.1080/02827588609382427

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In northern coniferous forests nutrient release from litter occurs primarily in late stages of decomposition when mainly extensively lignified parts remain. An important regulating factor in these stages is the turnover rate of lignin and related compounds. Two factors which influence the decomposition rate of lignin are 1) nitrogen concentration which retards decomposition and 2) concentration of celluloses which increase the turnover rate. The amount and composition of humus which is formed may be dependent on the initial lignin concentration of the litter, which in its turn varies among species. These results from studies in northern coniferous forests are discussed in an ecosystem context.

ISSN:0282-7581    

DOI:10.1080/02827588609382428

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Roots of 1‐year‐old containerized seedlings of Scots pine(Pinus sylvestrisL.) and Norway spruce(Picea abies(L.) Karst.) were experimentally frozen in December. The seedlings were then grown for 3 weeks in a growth chamber and evaluated with regard to root growth capacity (RGC) and shoot elongation. The subsequent RGC of Scots pine declined as root zone temperatures were lowered from ‐6°C to ‐11°C and from ‐11°C to ‐16°C. Almost no root growth was observed after exposure to ‐20°C. Shoot growth was also negatively affected by low root temperatures but less than root growth. Low root temperatures did not affect Norway spruce as much as Scots pine, although root and shoot growth of Norway spruce were reduced after exposure to the lowest test temperatures (‐16°C and ‐20°C). The length of exposure, ranging between 1 and 8 hours had no effect on subsequent growth.

ISSN:0282-7581    

DOI:10.1080/02827588609382429

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper is an attempt to measure the supply consequences of the thinning subsidy which was in operation during the cutting season 1979/80. The econometric analyses are based on a questionnaire to a sample of 2500 private non‐industrial forest owners, which was produced by the official Swedish investigation SOU 1981:81. The analyses show that it is questionable whether the subsidy did affect the total cut. The estimates of the supply increase range from an average of zero to 122 m3/owner. As a by‐product we obtain estimates of the price elasticity of the private non‐industrial forest owners supply curve. These estimates range from 0.63 to 1.69.

ISSN:0282-7581    

DOI:10.1080/02827588609382430

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Free amino acid and protein levels, and γ‐glutamyltransferase activity in apical buds and shoots of Scots pine during the growing season. The aim of the study was to obtain the basic information about nitrogen mobilization needed in carrying out studies on the optimal nitrate and ammonium ratios in the metabolism of Scots pine (Pinus sylvestrisL.). Considerable seasonal changes in the concentrations of free amino acids and other ninhydrin‐positive low molecular‐weight compounds were observed in the buds and shoots of Scots pine. 43 different amino compounds were identified, the concentrations of arginine, glutamine, glutamic acid, γ‐aminobutyric acid, alanine and aspartic acid being highest at the break of dormancy. The amounts of certain amino compounds decreased during the growing season, those of arginine, ethanolamine and various ammonium compounds in particular. The amount of glutamic and aspartic acids, glycine, alanine and γ‐aminobutyric acid, however, remained relatively constant. The protein concentration and the specific activity of γ‐glutamyltransferase increased towards the end of the growing period. Slight differences were found between the fertilized trees and the control trees.

ISSN:0282-7581    

DOI:10.1080/02827588609382431

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Six provenances of bothPseudotsuga menziesii(Mirb.) Franco andPinus contortaDougl. from a range of locations in the interior of British Columbia between latitudes 49° and 58° were grown for 80 days in controlled environment chambers programmed to provide daylengths comparable with those at either latitude 48°, or latitude 58°, during the period from mid‐June to early September. Neither shoot : root ratio nor whole plant dry weight ofP. menziesiiwere affected by photoperiod. However,P. contortaseedlings, which unlikeP. menziesiiset bud during the experiment, had a greater dry weight and a higher shoot:root ratio (p<0.05) under longer daylengths. The results appear relevant to the interpretation of effects of cross‐latitudinal provenance transfer on plantation productivity.

ISSN:0282-7581    

DOI:10.1080/02827588609382432

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Seventy‐four half‐sib families of lodgepole pine(Pinus contortassp.latifoliaEngelm.) plus trees were measured for vigour, height growth, stem diameter, wood density and ring width in two Swedish field trials at age 9. Height growth, wood density and ring width differed between families within provenances with variance components of 3–8 %. Coefficients of variation were highest for height growth and lowest for ring width. Heritabilities were similar for height growth and wood density but lower for ring width. These genetic parameters seemed to be equal for all provenances. Indirect selection for high dry stem biomass was more effective using height growth than wood density, and a correlated response in wood density of 2.1 % of mean by selecting the 15 highest parent trees was indicated. Juvenile wood density looks uncertain as a selection criterion for mature wood density.

ISSN:0282-7581    

DOI:10.1080/02827588609382433

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The present knowledge on birch genetics is reviewed as regards the fields of cytology, crossability within and between species, flowering, plant growth rhythm, tree growth and quality, and hybridization. Incompatibility occurs but can be partly overcome by crossing at low temperature. Species hybridization was more successful when the female parent was of low ploidy. Crosses within one subsection are not more successful than crosses between subsections. Earliness of male and female flowering can be improved by selection. Flowering is probably polygenically inherited. Clinal variation in north‐south direction occurs for growth rhythm characters, the northern provenances show the earliest growth cessation. Long‐distance transfers northwards or southwards result in reduced growth. The ratio between the family and the population variance components varies with type of character studied and the geographic range of the material studied. Long‐distance crosses within a species or between species do not seem to lead to any hybrid vigour. Definite conclusions must await more comprehensive crossing programs.

ISSN:0282-7581    

DOI:10.1080/02827588609382434

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Abies nordmannianaandPicea abiesseedlings were inoculated with a wild‐type (C 58) or an attenuated strain (rooter or shooter mutants) ofAgrobacterium tumefaciens. Large tumours were formed onA. nordmannianain response to the wild‐type and rooter strains, 60–65%of the seedlings being susceptible. Smaller tumours were formed onPicea abiesin response to the wild‐type strain, at least 12% of the seedlings being susceptible. Tumours from both species induced by the wild‐type strain grew in vitro on medium without added phytohormones.

ISSN:0282-7581    

DOI:10.1080/02827588609382435

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor