摘要:

Although a good correlation has been found between the mean degree of damage and the increment trend of larger Norway spruce collectives, individual spruce trees often betray no relationship between crown damage and the development of the volume increment. Detailed investigations show that stem and crown dimensions, growing space as well as the competition of neighboring stems can substantially outweigh the influence of crown damage on the volume increment. Furthermore, current methods to determine crown parameters and needle loss are in many cases quite error‐prone. Use of more accurate techniques for measuring spruce trees produced a stronger relation between the volume increment per square meter crown surface area and the degree of crown damage (needle loss).

ISSN:0282-7581    

DOI:10.1080/02827588609382416

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Yellow Cress (Rorippa sylvestris(L.) Besser), a weed difficult to control when established, has recently invaded Swedish nurseries. The properties of the species, as well as measures to avoid its further spreading, are described based on an exhaustive dissertation, other literature and own observations. It is most important to apply preventive measures to stop the species from being introduced and to observe the first establishment phases of the species. If it becomes established it is exceedingly important to prevent the spread of vegetative reproductive organs to unaffected areas.

ISSN:0282-7581    

DOI:10.1080/02827588609382417

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The time constant of the dehardening of one‐year‐old Scots pine(Pinus sylvestrisL.) seedlings was studied in three experiments started at different times of the year. The seedlings were transferred from outside to the different controlled conditions in January (Exp. 1), March (Exp. 2) and April (Exp. 3). Changes in the frost resistance of the seedlings were followed on the basis of the temperature response of the specific impedance difference in the shoot. The time constant for dehardening at a temperature of 7.5°C was found to be about 12 days in Exp. 1, about 8 days in Exp. 2, and about 5 days in Exp. 3. the terminal bud burst when the frost resistance of the shoot had risen to about ‐10°C.

ISSN:0282-7581    

DOI:10.1080/02827588609382418

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Results are presented from a 30‐year‐old Scots pine provenance trial series covering all Sweden. Variation in total yield is studied and the effect of transfer on this trait. The results show that significant differences exist between provenances in almost all trials. The variance component for provenance effects is about 60% of the total variation. Repeatabilities are found to be high, indicating reliability of data. Based on a response surface model and a contour plotting procedure, transfer functions for southern and northern Sweden respectively, are built. For southern Sweden, a transfer of ±1° combined with an altitudinal downward transfer of 100–200 meters, is proposed. In northern Sweden, no optimum transfer range is found. The function, however, shows that a southward and upward transfer, in combination, gives remarkable gains in total yield.

ISSN:0282-7581    

DOI:10.1080/02827588609382419

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Twenty sets, each consisting of a tall, a medium, and a small plant, were selected from a 2 by 2‐year‐old nursery crop. Selection differential was measured. Cutting propagation was undertaken and the subsequent clones were tested in a field experiment. Differences between groups at age 1, 2, 3, 6, 8, and 10 were calculated, and ortet/ramet regressions and age‐to‐age correlations were conducted. Selection of the tall plants gave a response of approximately 17% at age 10. Accumulated genetic gain at this age by a specified stepwise selection procedure is estimated to 36%. Step one is the early selection in the nursery, step two is a later selection amongst the early selected clones and performed after 7 years’ field testing. Ageing of clones, selection for other traits and application of the clones over a variety of sites will reduce these gains.

ISSN:0282-7581    

DOI:10.1080/02827588609382420

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The likelihood of detecting decay present in Norway spruce trees when taking bore core samples at breast height or at stump height was analyzed in two stands. The actual numbers of decayed trees were obtained after the trees were felled. More than 80% of the decay extending to breast height level was detected by taking core samples at that level. However, these core samples revealed only 40–70% of the actual amount of decay present at stump height. At stump height a higher portion of the total amount of decay present was revealed.Heterobasidion annosumwas detected in 69 and 77% of the decayed trees in the two stands.

ISSN:0282-7581    

DOI:10.1080/02827588609382421

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Isozyme‐analysis techniques have been applied to test the efficiency of supplemental mass pollination in a seed orchard ofPinus Sylvestris. Mass pollination was done on one single occasion before the general pollen dispersal. The results of isozyme analyses of seed after mass pollination demonstrate that it is possible to introduce desirable genes into the seed orchard crop. Mass pollination without isolation of female strobili gave an average contribution of 4% to the total fertilizations and after isolation of female strobili 26.5%. The main conclusion is that supplemental mass pollination offers very interesting possibilities for breeding, particularly if some kind of isolation of the female flowers is made. It can increase the seed quality as well as improve the breeding value of the seed orchard. More attention should be paid to increasing the efficiency of the controlled pollination. It is suggested that in the future, more effort is invested in improving the technique of mass pollination.

ISSN:0282-7581    

DOI:10.1080/02827588609382422

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect on litter decomposition rates was studied after annual additions for four years to the forest floor of sulfuric acid (64 kg S.ha−1), sulfur powder (64 kg S.ha−1), and in the first year limestone (dolomite) powder (412 kg Ca+230 kg Mg.ha−1). The litter was Norway spruce needles which were incubated in the field in litter‐bags. Drastic reductions in decomposition rates were observed and the addition of diluted acid caused a rate reduction to 66%of that in control and the additions of sulfur powder a reduction to 80%. The effect of the sulfur powder on litter mass‐loss rate appeared to be delayed and could not be noted until one year after the first addition. No effect could be seen of the limestone powder.

ISSN:0282-7581    

DOI:10.1080/02827588609382423

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Eight trees were selected at age eight years from seed in each of 52 full‐sib families ofPicea abiesand were propagated by rooted cuttings. The parents were both of Norwegian and German origin. Results are presented for the variation in height growth in the progeny test and in the clonal test, for rooting percentages, and for plagiotropic growth. More than 40% of the total variance of rooting percentages is of genetic origin. In the set of crosses between Norwegian and German parents 18% of the clones were classified as plagiotropic, while the same number was 27% in the crosses between Norwegian parents. The plagiotropic growth reduces the correlations between ortets and ramets both at the individual and at the family level. Family information is important in the selection of ortets, and a culling of plagiotropic clones seems necessary to obtain a substantial gain from selection.

ISSN:0282-7581    

DOI:10.1080/02827588609382424

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Seasonal changes in the N and P content of foliage in a young forest ofFagus sylvaticawere measured. Leaves from branches of the upper and lower crown of dominant trees and from suppressed trees were compared. Nutrient retranslocation rates during senescence differed considerably between trees. This variation appeared not to be related to any differences in environmental factors or tree vigour, and was probably genetically induced. In dominant trees the most efficient retranslocation of N was recorded in the upper crown and probably resulted from higher leaf temperatures and a longer senescent period in the sun leaves than in the shade leaves. Phosphorus retranslocation efficiency was higher in suppressed trees than in dominant ones, but no such tendency was observed with N. The most obvious difference between leaves at different crown levels concerned the time at which P translocation began; an outflow of P from leaves in the lower crown began in June, while in the upper crown this outflow did not begin until September/October.

ISSN:0282-7581    

DOI:10.1080/02827588609382425

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor