摘要:

The lipid composition of the two closely related birchesBetula pubescensandBetula tortuosawas investigated. The total amount of lipids and the lipid composition was strikingly similar. The glycolipid content on a chlorophyll basis was high in both birches. A comparison of the. acyl groups revealed a small difference in 16:3 in monogalactosyl diacylglycerol, but the total amount of trienoic acids was similar. The acyl group composition in the nonplastid lipid phosphatidyl choline differed between the birches andB. tortuosahad a higher average number of double bonds. The observations on galactolipid and phospholipid could not explain the earlier stated higher tolerance ofB. tortuosato the freezing of its leaves

ISSN:0282-7581    

DOI:10.1080/02827588909382581

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The theoretical background to wood production is outlined and the factual background is given by reviewing measured rates of wood production. It is recommended that differences in wood production be analysed, not by statistical methods, traditional growth analysis or by comprehensive models, but by using a ‘light use analysis’, where wood production is determined by (1) the amount of light intercepted by the canopy, (2) the light use efficiency, net of respiration, (3) the proportion of assimilates partitioned to wood, and (4) mortality losses. These four components are discussed.

ISSN:0282-7581    

DOI:10.1080/02827588909382582

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The individual tree growth in stands of mixed Norway spruce (Picea abies(L.) Karst.) and birch (Betula pendulaRoth &Betula pubescensEhrh.) is estimated using basal area and height growth functions for each species separately. The individual tree growth models are distant dependent and the number, size and proximity of neighbours are expressed as size‐ratio competition indices. The competition indices were calculated using a basal area factor gauge to define competitors. The tree growth functions are based on data from nine mixed stands of Norway spruce and birch. The recursive multivariate regression approach is used. The growth functions have standard deviation about the function/standard deviation about the mean (sf/sm) values between 31 and 61% and the evaluations made with root mean square error (rmse) give estimates which vary between 8 and 45%of the observed mean value. These values are comparable with the precision reported in other studies. In the present investigation the distant dependent indices are important independent variables. It seems suitable to describe the change in growth conditions from retarded to released growth by means of size ratio competition indices. For birch, a positive effect on growth is obtained the more the total competition consists of Norway spruce. For Norway spruce a negative effect on growth is obtained the more the total competition consists of Norway spruce. The lower competitors have a positive effect on the growth of the spruce trees. The interpretation should be that it is better to have a small competitor than a larger one, not that small competitors as such have a positive effect on growth of Norway spruce.

ISSN:0282-7581    

DOI:10.1080/02827588909382583

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The proportion of background pollen grains in the seed crops of twoPinus sylvestrisseed orchards in Central Finland was estimated with the aid of multilocus allozyme markers. The orchards studied were more than 30 years old and in full pollen production. For the bulked seed crops of the seed orchard with southern clones the estimated average of background pollination over four years was 26%. There were statistically significant differences between years. No significant heterogeneity in the degree of background pollination between clones was found. Among single ramets there was significant heterogeneity in the estimated contamination rates, but the variation was not related to position in the orchard. For the seed orchard with northern clones the bulked seed crop was studied only for one year and the level of background pollination was found to be 33%.These estimates are fairly high, but lower than for many other orchards. Background pollination at this level will cause losses in expected genetic gains. Part of the seeds from northern orchards will not be adapted to the intended area of use.

ISSN:0282-7581    

DOI:10.1080/02827588909382584

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The common rhizospheric fungusCylindrocarpon destructanswas investigated in relation to its role in root death ofPinus sylvestrisin Nordic nurseries and plantations. Laboratory methods were developed for studying similar root problems as well as the early effects of phytotoxicity and fungal infection. Seedlings grown under standardized optimal conditions were exposed to controlled stress (known to occur in nurseries), with or withoutC. destructansin the rhizosphere. Low light conditions, anaerobic root environment, and fungicide treatment were each found to predispose pine seedlings to invasion by the pathogen. The pathogen was very sensitive to competition as well as antagonism on the root, and fungicide‐induced inhibition of antagonists such asTrichodermaspp. also increased the severity of attack by the pathogen. To compete successfully, the pathogen would have to invade and dominate weakened roots prior to the arrival of saprophytes. Toxic metabolites produced by the pathogen weakened or killed nearby root tissues, and pathogen metabolites seemed to prevent saprophytes from taking hold in the infected roots. Such heavily infected, dead roots may act as inoculum sources allowing the pathogen to invade adjacent living roots, even healthy ones. Dead roots left in nursery soil after earlier harvests may act as reservoirs of inoculum for long periods and pose a threat to new plants.

ISSN:0282-7581    

DOI:10.1080/02827588909382585

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The effectiveness of a stocking, constructed of nylon and cotton netting, in protecting containerized conifer seedlings against pine weevil attack was evaluated in field tests on 37 clear‐cut reforestation areas in southern and central Sweden. The stockings significantly reduced pine weevil feeding on treated seedlings as well as seedling mortality. The protective effect of the stockings was similar to that of an insecticide (permethrin) treatment. In most experiments the survival of stocking‐enclosed seedlings was satisfactory from a practical point of view, whereas untreated control seedlings suffered heavy mortality.

ISSN:0282-7581    

DOI:10.1080/02827588909382586

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Seedlings of Scots pine(Pinus sylvestrisL.) and lodgepole pine(P. contortaDougl.) provenances, as grown in Finland, were inoculated with “m”; and “r”; “forms”; of the pinewood nematode (Bursaphelenchus xylophilus)from Canada, anmform isolate from France and anrform isolate from Missouri, USA. Scots pine was highly susceptible to an Albertarform and a British Columbiamform isolate and moderately susceptible to two Quebecmform isolates. Lodgepole pine was higly susceptible to the tworform (Alberta and Missouri) isolates and moderately susceptible to the British Columbiamform and the two Quebecmform isolates. Mortality of both pines after inoculation with the French isolate was inconsistent. Mortality of both pines occurred more rapidly following inoculation withrform than with m form nematodes. Large numbers of nematodes were generally found in the tissues of both pines. Our results with seedlings need to be corroborated by inoculating larger field‐grown trees.

ISSN:0282-7581    

DOI:10.1080/02827588909382587

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor