摘要:

Fifty pole stage trees were inoculated withO. polonicumat monthly intervals between May and September. Most infection, measured as the area of sapwood blue‐stained, occurred in July and least in May and September. The difference between July, August and September might be explained by the effect of temperature on fungal growth, but in May and June the trees had a higher resistance than expected. Tree resistance was correlated with resinosis. Tree variables not correlated with resistance were DBH, annual ring width, periodic growth, vigor index, or phloem carbohydrate concentration.

ISSN:0282-7581    

DOI:10.1080/02827588809382500

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Browse production after two growth seasons following mechanical cutting and glyphosate spraying was 60% and less than 1%, respectively, of production before treatment. Moose (A. alces)utilization of forest plantations decreased significantly the first and third winter after spraying. The second winter there was also a decrease, although not statistically significant. Browsing byA. alcesrelieved the spruce seedlings from considerable competition by hardwoods. Browsing also altered the hardwood composition of the forest plantations, from rowan(Sorbus aucuparia)dominance to birch(Betulasp.) dominance.

ISSN:0282-7581    

DOI:10.1080/02827588809382501

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The mountain hare's (Lepus timidus)use of sprayed and unsprayed parts of a forest plantation was studied using pellet counts, radiotracking and a winter feeding site survey. There was a strong reduction in use byL. timidusthe first year after spraying. The second year after spraying the difference between sprayed and unsprayed parts was small by comparison. It was concluded that spraying of forest plantations up to at least 10 years after logging mainly affects the spring habitat ofL. timidus.

ISSN:0282-7581    

DOI:10.1080/02827588809382502

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Habitat preference of adult black grouse (T.tetrix)in relation to glyphosate spraying of conifer plantations was studied in SE Norway. TenT. tetrix, six cocks and four hens, were fitted with radio transmitters and followed from late May through July 1985. Although we were not able to establish statistical significance, it appears that both cocks and hens avoid sprayed plantations the first one to two years after treatment, but after four to six years the plantations are used regularly by hens; the material on cocks is inconclusive. On certain sites vegetation development after spraying may be favourable to hens, but glyphosate spraying appears generally unfavourable to cocks. Therefore spraying plantations close to the leks is not recommended, as these are preferred summer habitats of the lek‐cocks.

ISSN:0282-7581    

DOI:10.1080/02827588809382503

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Seeds of lodgepole pine(Pinus contortaDougl. var.latifoliaEngelm.) collected southwest of Grande Praire, Alberta at three different times and altitudes between August 20, 1984 and August 15, 1985 showed variable responses to stratification. The responses were related to seed ripeness, as judged through evaluations of cone moisture contents, and with the length of time that the cones had remained on the trees. Unripe seeds started to lose germination in the third year after pollination when on the tree. Mature seeds which lost germination by late fall 1984 regained it by the next fall, while most unripe seeds did not. Immature seeds increased their need for stratification over time while mature seeds did not. Seeds should be left on the tree until the end of the third year to insure maximum viability because they do not reach maturity until then.

ISSN:0282-7581    

DOI:10.1080/02827588809382504

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The causal relationships between shoot growth variables were analysed on the basis of a study in the Phytotron where six full‐sib families ofPicea abiesL. (Karst.) were grown for six growth periods. Phenotypic correlations and path analysis were used for the analysis of causes. The phenotypic correlations were estimated in three different ways: 1) separate analyses within each growth period based on individual tree data, 2) based on family means at different growth periods (0, and 3) using differences in family means between two consecutive growth periods(dt). The two methods based ontordt‐values gave different results in a number of cases. We argue that, because of the rapid concurrent changes that occurred between growth periods, we could not conclude that the correlations based on family means (t) reflected causal relations and, also, that the method based ondt‐values gives a better indication of causal relationships between different variables. Usingdt‐values, the variation in shoot elongation period was mainly explained by the variation in free growth (82%) while the variation in shoot growth initiation only explained a minor fraction. Variation in leader length was mainly explained by growth rate and only to a minor extent by shoot elongation period, meaning that the observed decrease in shoot elongation period did not cause a corresponding changé in leader length. One conclusion from this finding is that we do not necessarily lose growth capacity if we breed for a better adapted growth rhythm (i.e. shorter shoot elongation period) of the seedlings.

ISSN:0282-7581    

DOI:10.1080/02827588809382505

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Fertilization is modelled on the basis of two concepts, nutrient flux density in the soil (amount of nutrient available per unit of soil and unit of time) and nutrient productivity (growth rate per unit of nutrient in plant). The nutrient productivity is used to calculate the nutrient uptake rate which is required to maintain the internal nutrient status constant at optimum and which, therefore, is required to be matched by the nutrient flux density. By supplying fertilizer nutrients as an addition to the flux density, high utilization of the added nutrients may result. A simple application of the model is, therefore, to increase the current nutrient flux density to a specified rate by the fertilizer additions. Increased accuracy of fertilization is possible by adjustment of the dosage also to the potential uptake rate of the crop. The relationships in the model are discussed on the basis of nitrogen nutrition but the use of complete fertilizers is recommended. The parameters needed, including weather data, to calculate fertilizer dosages over the growing season are discussed. A computer‐adapted technique is suggested, using an irrigation system to distribute a liquid fertilizer. In this way experiments can be done to increase knowledge about nutrient dynamics and crop properties and to improve the model so as to develop more efficient fertilization routines with minimal nutrient leaching and environmental hazards.

ISSN:0282-7581    

DOI:10.1080/02827588809382506

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Development in height, diameter and basal area was studied for beeted and for originally planted Norway spruce(Picea abies(L.) Karst.) seedlings. The study was carried out as a survey in three unthinned stands in southern Sweden. Beeted seedlings were separated from those originally planted by differences observed in the number of annual rings at stump height. In all stands height and diameter were smaller and growth rates in height and basal area were lower for beeted than for originally planted seedlings. The lower growth rates for beeted seedlings may be explained as effects of inter‐tree competition. The oldest stand was thinned at the time of inventory. 40% of the thinned trees were beeted representing 18% of the thinned volume.

ISSN:0282-7581    

DOI:10.1080/02827588809382507

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The growth and structural development of Scots pine(Pinus sylvestrisL.) trees growing at different spacing was simulated using a model based on the dry matter production per needle biomass unit and its allocation to needles, branches and stem. Special emphasis was given to the effect of stand density on the growth of the crown system and its implications on branchiness and timber quality. The simulations showed that the needle biomass culminates considerably earlier than the branch biomass with a time lag inversely related to the stand density. The lengths of living and dead crown were also inversely related to stand density. The resulting differences in branchiness were especially obvious in the early development of the tree stands. In the long run these differences tend to disappear, indicating equal external branchiness independently of the initial spacing for mature stands of Scots pine. The internal branchiness, however, was particularly sensitive to the initial spacing.

ISSN:0282-7581    

DOI:10.1080/02827588809382508

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A field experiment was established in twoPicea abies(L.) Karst. plantations in southern Sweden to study yield and effects of competition on growth in beeted stands. Beeting was carried out in gaps where originally planted seedlings had been removed. Tree species used for beeting wereP. abies, Pinus sylvestrisL.,Pinus contortaDougl. andLarix deciduaMill ×L. leptolepisGord. The plantations were beeted when mean heights were 95 cm (Ullasjo) and 40 cm (Knäred). Effects of competition on diameter growth of P.abieswere found when originally planted stands were 2.5 and 3.5 m in height. On both sites, diameter growth in stump height was significantly lower for seedlings beeted in small gaps (approx. 20 m2) than for seedlings beeted in the middle of large gaps (approx. 155 m2). This difference was larger at Ullasjo than at Knared. About 50 % of theP. sylvestris70%of theP. contortaand 80% of theL. deciduaxL. leptolepiswere dead or severely damaged six years after beeting. The main causes of damagewerefraying and browsing by moose and roe‐deer.

ISSN:0282-7581    

DOI:10.1080/02827588809382509

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor