摘要:

The effect of night temperatures on the gas exchange of naturally established Scots pine(Pinus sylvestrisL.) seedlings was investigated at a site with frequent summer frosts in northern Sweden. During the growing season, a reversible inhibition of light‐saturated rates of CO2‐assimilation was observed after nightfrosts. Stomatal conductance decreased or increased in parallel with changes in the CO2‐assimilation rate. The inhibition of photosynthesis was not primarily the result of stomatal closure, since intercellular CO2‐concentration increased after night frosts. Naturally regenerated Scots pine seedlings survived repeated frosts during the growing season and showed no visible damage although air temperatures as low as ‐8.2°C were recorded during the period of shoot elongation

ISSN:0282-7581    

DOI:10.1080/02827588809382530

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Three test series were planted on sites selected for their contrasting properties to study the genotype × site interaction. Various clones ofSalix alba(8 clones in the 1980 series),S. dasyclados(8 clones in 1982 series) andS. viminalis(6, 9, 13 clones in the various series) were included. Growth capacity, survival and infection by rust fungi were analysed. Interspecific variation was seen at some of the sites in the 1982 series but it was pronounced in the 1980 series where 5.viminalisoutgrew 5.albaat all sites. Intraspecific variation could be seen for growth capacity, survival and rust resistance. A genotype × site interaction was detected for all variables studied. Some of the interaction, especially at the species level, can be explained by the variation in susceptibility to rust fungi and preference for soil types. In the breeding work withSalixthe genotype × site interaction must be considered.

ISSN:0282-7581    

DOI:10.1080/02827588809382531

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Two “classical” theories, both originating in Elias Melin's laboratory in Uppsala, have tried to explain the regulation of ectomycorrhiza formation. The carbohydrate theory, formulated by E. Björkman in 1942, identifies root carbohydrate concentrations as regulatory, while these are in turn considered to be strongly influenced by plant mineral nutrition and light conditions. The hormone theory, expounded by V. Slankis in the 1960s, claims auxin of fungal origin to be the key regulator, influencing root carbohydrate status, while the fungus itself may, to some extent, be affected by mineral nutrition. Both theories have been subject to much discussion and have led to further work, without ever having been conclusively proven experimentally. Recent results in Uppsala and elsewhere have shed new light on several of the key issues. The development of research in this field since 1942 is critically reviewed in light of later data, and a unifying theory is sketched on the basis of E. Hacskaylo's proposal from 1969 to reconcile contradictory results.

ISSN:0282-7581    

DOI:10.1080/02827588809382532

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Picea abiesmother‐plants from 10 serially propagated clones (14 years old, chronologically) were treated in four different ways: (1) control with intact, non‐manipulated plants; (2) like (1) but with the leader cut off; (3) intact plants but with all branches of the upper two whorls forced to grow in a vertical way; and (4) like (3) but with the leader cut off. Cuttings from four positions (cutting‐types) on the mother‐plants were collected, rooted and evaluated for rooting%, number of main roots, number of lateral roots, plagiotrophy, needle symmetry on leader and growth of leader. Treatments 3 and 4 resulted in cuttings with more plagiotropic growth but with better rooting, more lateral roots and better growth than did cuttings from treatments 1 and 2. The genotype had a significant influence on rooting. Number of main roots was significantly influenced by the genotype and the cutting‐type, but not of the mother‐plant treatment. Symmetry of needles on the leader was fairly weakly influenced by genotype and cutting‐type yet not influenced by mother‐plant treatment. Clone effect was significant for leader growth.

ISSN:0282-7581    

DOI:10.1080/02827588809382533

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Four field experiments are described in which Scots pine (Pinus sylvestrisL) seed was sown in indentations made by pyramidal tools of different form (square base = 4 cm; angles from 44 to 90°; depths from 1 to 5 cm). The indentations were made in the ridges and furrows of a conventional harrow track. Overall, the best treatment was to make shallow indentations (tools: 90°‐1 or 2 cm; 67°‐1 or 2 cm; 44°‐1 cm deep) in ridges of the harrow track. In three experiments these indentations gave at least twofold seedling emergence compared with the control in ridges (seeds sown on soil surface). Soil texture in combination with precipitation affected the emergence results of the different indentation treatments. Indentations in ridges made by tools with a depth of 3 cm or even more gave good results if the soil was stable. For operational purposes the wear‐resistant form “90°‐1 or 2 cm” should be advantageous. The loss of seedlings, as measured up to the end of the third growing period, was significantly more rapid in furrows than in ridges.

ISSN:0282-7581    

DOI:10.1080/02827588809382534

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The changes in basal area, volume and tree shape in an ‘optimum fertility trial’ in Norway Spruce were studied after the treatments had been applied for 15 years. There was a marked response to N and a lesser response to P. Increased average tree taper was associated with the N application. Form factors tended to show less change, but, even allowing for tree height responses, there was up to a 10% reduction. Phosphate fertilizer in the presence of N increased form factor slightly; applying a ‘complete’ fertilizer reduced form factor and increased taper while the trees were under about 6 m tall. The use of individual treatment regressions of volume on basal area resulted in increased precision in estimating the volume of individual treatment means.

ISSN:0282-7581    

DOI:10.1080/02827588809382535

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The role of nitrogenous compounds in the pest‐host interaction ofAradus cinnamomeusandPinus sylvestriswas studied by analysing free amino acids and related compounds in the insects and the cambial layer of Scots pine. About 35 different compounds were identified by means of thin‐layer and automatic ion‐exchange chromatography. The total content of amino acids in the insects was ca. 0.86% of the fresh weight (65 μmoles/g), ca. 0.075% (7.2 μmoles/g) in the young phloem layer of Scots pine, and ca. 0.078% (6.8 μmoles/g) in the young xylem layer. The most abundant free amino acids in the insects were proline and glutamine, followed by alanine, glutamic acid, taurine, histidine, arginine, and lysine. The amino acid composition was similar in males and females, and almost identical in brachypterous and macropterous females. The concentration of glutamic acid was low in the hemolymph but high in the salivary glands and other tissues. In other respects the amino acid composition of the salivary glands resembled that of the whole insect. No distinctly phytotoxic compounds were identified in the insects. The predominant amino compounds in the cambial layer of the pine saplings were γ‐aminobutyric acid, glutamine, ethanolamine, serine and alanine. The amino acid composition was similar in extracts of phloem and xylem. The bulk of the alcohol‐soluble compounds in the pine cambial layer were carbohydrates (ca. 3.5% of fresh weight).

ISSN:0282-7581    

DOI:10.1080/02827588809382536

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Invertebrate abundance was estimated in 1981 and 1982 by sweep‐netting at twelve forest vegetation types in Vegårshei, Southern Norway. Invertebrates are expected to be a major determinant of habitat quality to gallinaceous birds, since animal food is considered essential to young chicks. The twelve fixed stations were chosen to illustrate poor and rich habitats and a gradient from bog to forest habitat. Rich vegetation types also had the highest abundance of invertebrates mainly due to moist and heavy soils. A comparison between a clear‐cutting and a similar vegetation type not logged, showed strong reduction in invertebrate availability after cutting. The influence of this alteration on availability of the capercaillieTetrao urogalluschicks’ food is discussed.

ISSN:0282-7581    

DOI:10.1080/02827588809382537

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Slides and computer drawings of 100 managed stands were evaluated for scenic beauty and recreational value by 121 people. The size and age of trees increased the beauty and recreation scores as well as a big share of pines and birches. A great number of stems per hectare indicated low amenity. Characteristics describing the tree population explained 70%of the variation in slide ratings. Ratings of computer illustrations of stands accounted for about the same proportion of the variation in slide ratings indicating that they can be used as successfully as the regression models for estimating the amenity of a tree stand. The ratings of forestry students did not differ from those of biology students nor the ratings of foresters from those of urban citizens.

ISSN:0282-7581    

DOI:10.1080/02827588809382538

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Satellite data were used in developing methods for forest inventory and mapping in a cooperation project involving Finland, Norway and Sweden. A goal was to improve the technical competence in forestry remote sensing in those countries. Landsat TM‐ and simulated SPOT‐imageries were classified using, e.g., filtered input data and contextual classifiers. The relative area distribution of usual forest classes was estimated at an acceptable accuracy. A two‐phase sampling scheme was introduced for compartmentwise (in‐place) inventories. The first phase involves analysis of satellite data, the second phase measurement of field plots. Correlations between satellite‐ and field‐measured values of various forest characteristics were relatively high, close to those obtained using aerial photo interpretation.

ISSN:0282-7581    

DOI:10.1080/02827588809382539

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor