摘要:

The distribution of different clones (genotypes) ofHeterobasidion annosumwas investigated in 34 clear‐cut pure and mixed Norway spruce stands. The proportion of admixed tree species, mostly birch and Scots pine, varied between 0 and 60%. The total area investigated was 35 ha.H. annosumwas isolated from 13.1% of the spruces: the S intersterility group from 11.8% and the P intersterility group from 1.3%. Only 0.7% of the pines and apparently none of the broad‐leaved trees had been attacked byH. annosum.The clones of this fungus were generally small: the mean number of spruces infected by one and the same clone was 1.8. The damage caused byH. annosumto spruce was slightly smaller in mixed stands than in pure spruce stands. However, other factors than the present stand composition proved to be much more decisive for the occurrence ofH. annosum.

ISSN:0282-7581    

DOI:10.1080/02827589009382598

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Effects of food quality on mortality and developmental rate of a Finnish population ofDiprion piniwere studied in the laboratory. The larvae were reared both on Scots pine needles taken from a site with a heavy pollution load, and from an area with no industry in the vicinity. Individuals reared on polluted needles tended to develop slightly at a slower rate and to hatch later than those reared on unpolluted needles. Cocoon mortality was higher in the group fed with polluted needles. Cocoon weight was not related to the hatching time within the groups.

ISSN:0282-7581    

DOI:10.1080/02827589009382599

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Using an econometric model of the sawtimber and pulpwood market in price region 1 (the northern part of Sweden), it is considered whether the subsidies paid to regeneration costs in this region have had any measurable effect on short‐run wood supply. The analysis is a continuation of the work presented by Brännlund et al. (1985b), in which it was claimed that subsidies have had a non‐positive effect on short‐run supply. A more elaborated test is used in this study. The test is based on the use of a reference model which, in this case, consists of an econometric model for the whole country of Sweden. The results from the test cannot be used to reject the conclusion that subsidies have had a non‐positive effect on short‐run wood supply.

ISSN:0282-7581    

DOI:10.1080/02827589009382600

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The paper presents a method where the mor layer was sliced into 1 cm thick layers before measuring of pHH2Oand pHCaCl2. A significant decrease of pH with increasing depth was found. Except for the two deepest layers, 2–3 and 3–4 cm, pH of all layers were significantly different (p<0.001). There was a significant positive correlation between pH in adjacent cm‐layers within the cores. pHH2Oin the middle layer, 1–2 cm, showed a significant correlation with all other cm‐layers. This may indicate that a vertical influencing factor or factors determine the pH pattern, even in spots with deviating pH values compared to the sample plot mean. Alteration of the organic material during decomposition, leaching of organic acids and cation uptake are discussed as probable factors leading to the observed pH gradient. The preferability of calculating a mean pH value from untransformed logarithmic pH values was also confirmed.

ISSN:0282-7581    

DOI:10.1080/02827589009382601

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Experiments were conducted to determine growth and ethylene evolution in seedlings and coppiced plants ofBetula pendulaRoth andB. pubescensEhrh. when subjected to stresses relevant to the maintenance of natural forests, and especially in fuelwood plantations, i.e. cutting of the stem, thinning, bending, flooding and various combinations of these. Most of the experiments were carried out in the laboratory using 1‐year‐old seedlings or 1‐month‐old sprouts. Height and diameter growth, biomass production, morphology and ethylene evolution were studied for 1–2 months. Material for comparison was obtained from young sprouts on the stumps of fully developed trees growing under natural conditions and natural seedlings of a comparable age. Exposure of seedlings and coppiced plants to stress factors usually altered growth and increased ethylene evolution. Cutting of the stem and thinning had similar effects in that they stimulated transient ethylene evolution by both roots and stems. Bending retarded the height growth to some extent, while increasing the ethylene content especially on the lower side of the horizontal stem. Flooding arrested height growth and increased ethylene evolution in the roots. The two species reacted basically in similar ways, butB. pendulaproduced more ethylene. though at a slower rate, and also showed a more pronounced retardation of growth. The sprouts had a higher ethylene content than the seedlings and also increased their ethylene evolution more rapidly. The changes in ethylene evolution and growth are discussed from the point of view of the resilience of the plants and as an indication of stress factors in experimental plots.

ISSN:0282-7581    

DOI:10.1080/02827589009382602

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This study applies the Strahler ordering to the description of the branching of 25 young Scots pines(Pinus sylvestrisL.). The total number of segments in the crown increased as a function of tree size, the logarithmic value of the number of segments in a particular order being a linear function of the segment order. This branching pattern was strong in accordance with the expected number of shoots belonging to each Strahler order as derivable from the prevailing literature. The branching ratio was 4.0–5.3, which is close to the values reported to be characteristic of severalPinus‐species.

ISSN:0282-7581    

DOI:10.1080/02827589009382603

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Temporal variation in nutrient concentrations of Scots pine(Pinus sylvestrisL.) needles was studied during a three‐year period in three stands of differing stages of development. Concentrations of N, P and K varied significantly between years; this variation was related to differences in needle dry weight. Concentrations of all measured nutrients (N, P, K, Ca, Mg, Mn, Cu, Zn, Fe, B) and Al varied between seasons; this variation was related to nutrient mobility and the annual physiological cycle. Concentrations of the mobile nutrients N, P and K decreased in spring and early summer during shoot and needle elongation and increased in late summer and autumn during needle senescence and litterfall. Concentrations of Mg, Cu, Zn and B followed somewhat similar patterns. The poorly mobile nutrients Ca, Mn and Fe accumulated gradually in needles during each growing season. Needle nutrient concentrations were stable during the nonactive period.

ISSN:0282-7581    

DOI:10.1080/02827589009382604

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Acclimation in seedlings and young plants of various ecotypes and crosses between ecotypes ofSalix pentandraL. were studied under natural climatic conditions at 69°39’ N lat. and in a phytotron. Rapid cold acclimation was initiated after cessation of apical growth and outdoors it occurred about four weeks earlier in a northern (from 69°39’ N lat.) than in a southern (from 59°40'N lat.) ecotype. F1‐populations from crosses between a northern and a southern ecotype gave an intermediate response. Experiments with different morphogenetic light treatments indicated that these treatments affected cold acclimation mainly through their effects on cessation of growth. There was, however, an indication that blue light, given during a daylength extension period, slightly prevented acclimation in seedlings of a northern ecotype. After budset cold hardening was effectively triggered by low temperatures (3°, ‐3°C), but also seedlings that were kept in short day conditions at a high temperature (12, 15°C) developed a significant level of frost hardiness (about ‐40°C) during a period of eight weeks.

ISSN:0282-7581    

DOI:10.1080/02827589009382605

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Comparison of seedling survival, by types of stock of lodgepole pine(Pinus contortaDougl. ex Loud.) and Siberian larch(Larix sibirica(Munchh.) Ledeb.), was made on mineral soils at four locations in Iceland. Planting tools and site preparation were also tested. After three growing seasons, variations in survival by locations were greater for Siberian larch (0–81%)than for lodgepole pine (34–65%).Large variations in survival were observed by types of stock and site preparation. The influence of planting tools was of minor significance. Container stock and transplants of lodgepole pine and Siberian larch, respectively, generally had the greatest survival. In general, site preparation had negative effects on lodgepole pine and positive effects on Siberian larch. The results imply, furthermore, that effects of glyphosate application on lodgepole pine are site specific. In conclusion, for given sites and species, a proper choice of stock and site preparation may greatly improve afforestation success in Iceland.

ISSN:0282-7581    

DOI:10.1080/02827589009382606

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Survival and early growth and yield ofSalix albaL. over two successive 2‐year rotations were evaluated under nursery conditions that included irrigation during the first growing season. A six‐year‐old coppice ofSalix albawas used as a source of cuttings. Cuttings were planted in single row plots at a 30 cm spacing within rows and 100 cm between rows. Cuttings ranged in size from <0.6 to 3.2 cm in diameter and 7.6 to 45.7 cm in length. Use of small cuttings resulted in lower survival with survival rates ranging from 13.3 to 100%. Cutting length and diameter were both significant factors, but cutting length was the most critical. The smallest cuttings that resulted in 100% survival after two rotations were 0.6 to 1.3 cm in diameter and 30.0 cm in length. Stem number, cumulative height, and biomass all increased markedly with use of larger cuttings up to a certain size and ranged on a per stool basis from 17.3 to 23.4, 14.3 to 20.2 m, and 194 to 300 g, respectively, at the end of the second rotation. Use of cuttings larger than 1.3 to 1.9 cm in diameter and 22.9 cm in length did not result in any significant improvement in growth. The conclusions are that cutting size can be an important factor influencing early plantation performance and use of mini‐cuttings to establish fast‐growing plantations is not recommended.

ISSN:0282-7581    

DOI:10.1080/02827589009382607

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor