摘要:

Nutrient concentrations in different tree compartments and the effects of PK(MgB) and NPK(MgB) fertilization were studied in a Scots pine(Pinus sylvestrisL.) stand growing on a low‐shrub pine bog in eastern Finland.

ISSN:0282-7581    

DOI:10.1080/02827589209382713

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The effects of thinning and fertilization, both singly and in combination, on the growth of 45 year oldPinus sylvestristrees, were studied in northern Sweden for five years after treatment. Based upon annual examination of trees for height and diameter growths, the radial, height and volume increments of the stems in relation to treatments were estimated. Thinning was found to increase stem radial growth after one year, while increased growth after fertilization appeared the second year. Thinning promoted lower bole growth, while fertilization increased upper bole growth. Thinning decreased height growth and fertilization increased height growth in the first year with associated increased volume increment. An increased volume growth for thinned trees was not found until the third year after treatment. Neither treatment caused changes in the length of the seasonal growth response or in the phenology of growth.

ISSN:0282-7581    

DOI:10.1080/02827589209382714

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A recent hypothesis predicts that folivorous rodents should better overcome plant defence if the vegetation is rich in minerals. Vole densities, damage to bark by voles and calcium, phosphorus and sodium contents of bark were compared for forest plantations on various soil types in north‐central Sweden. The folivorous field vole had a minor but prolonged cyclic population peak in a limestone area and showed a more rapid decline on granitic bedrock. Damage to seedlings was slight during this cycle but most extensive on abandoned fields and on hill slopes of newly cut forest, where seedlings contained higher levels of sodium and calcium in the bark, respectively. Factors other than food or minerals may drive the vole cycles but peak populations may still be limited by lack of certain minerals in vole food so that the animals then turn to mineral‐rich seedling bark. There was thus certain evidence of mineral effects and tentative recommendations are given on avoidance of vole damage on soils with high mineral content.

ISSN:0282-7581    

DOI:10.1080/02827589209382715

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Leader shoot damage was imposed on young Scots pines (3 m high) in four ways: by caging the uppermost whorl including the leader shoot with 10 pine shoot beetles; by caging the two uppermost whorls with 20 beetles; by topping the tree below the 1984 whorl; by topping the trees as above and removing all current shoots in whorl 1983. Six years later, top‐damaged trees were still significantly shorter than undamaged controls, although the annual height growth rate had recovered to the pre‐damage level within 3 years. Recovery occurred in two ways: lateral branches from the nearest intact whorl took dominance over the damaged leader or secondary branches developed from interfascicular buds on the damaged leader shoot. Approximately one and two years of height growth were lost in the former and latter case, respectively. Only 5 of the 34 top‐damaged trees escaped technical defects (crooks and/or vertical branches). Stem diameter and crown development were slightly affected.

ISSN:0282-7581    

DOI:10.1080/02827589209382716

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

I tested the presence of rapid and delayed induced resistance inPinus sylvestrisL. by biotests, rearing three species of diprionid sawflies on defoliated and undefoliated trees. I damaged the pines artificially by cutting mature needles with scissors at the beginning of the growing season. Four levels of defoliation were created on the basis of levels of removed needle biomass. Sawfly larval and cocoon weights were retarded and relative growth rates delayed as a result of an increase in damage level. The larval periods were prolonged at most 2–6 days. The response to the damage was partly species‐specific. The needle water content decreased in the following growing season in connection with low and moderate damage and increased at high damage levels. The nutrient contents of the foliage in the damaged and undamaged trees did not differ significantly. The Scots pine showed damage‐induced changes in food quality after extensive defoliation, which affected, via plant, species using the same host.

ISSN:0282-7581    

DOI:10.1080/02827589209382717

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper, a decision analysis method called the Analytic Hierarchy Process (AHP) is applied to multiple‐use planning of forest resources. Principles of the method are presented and its properties are discussed with regard to multiple‐use planning. An illustrative example is given, in which the decision alternatives are produced using linear programming. Both quantitative and qualitative decision elements can be dealt with when the decision alternatives are evaluated using the AHP. The preferences of the decision‐maker are accommodated by pairwise comparisons between the decision elements. An additive priority model is estimated based on comparisons. Due to its simplicity, flexibility, and high effectiveness in analysing complex decision problems, the AHP isveryapplicable in multiple‐use planning.

ISSN:0282-7581    

DOI:10.1080/02827589209382718

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper develops a simple two‐period present value maximizing model of forest management. The production possibility is determined by the initial forest endowment, a growth function and transformation relations between thinnings, final fellings, pulpwood supply and sawtimber supply. The model is applied on thinnings and final fellings data of three different ownership categories in Sweden; private industrial, private non‐industrial and public owners. The results show lower price elasticities than previous studies where no distinction between ownership categories are made. Also, a previously unused inventory variable seems to have an important explanatory power.

ISSN:0282-7581    

DOI:10.1080/02827589209382719

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0282-7581    

DOI:10.1080/02827589209382720

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The effects of test environments (dry versus wet) on estimation of genetic parameters in seedling traits were studied in 160 open‐pollinated families of Douglas‐fir(Pseudotsuga menziesii(Mirb.) Franco) from southwestern Oregon. Seedlings from four populations were grown in two test environments for two growing seasons. Between test environments, ‐9 bars of water potential difference were created in both growing seasons. Estimated genetic variances in most growth and phenology traits were considerably higher for seedlings grown in the wet environment than for those in the dry. Estimated genetic correlations between the same traits measured in different test environments indicated that most seedling traits studied for two growing seasons are genetically stable in both environments—i.e., suggesting that genotype by environment interaction in these traits are weak. However, the effect of test environment on estimation of genetic parameters in seedling traits, especially in adaptive seedling traits, should be evaluated very carefully when early evaluation of genetic entries is practiced in Douglas‐fir since these traits (budburst timing, lammas growth and free growth) appear to be plastic traits.

ISSN:0282-7581    

DOI:10.1080/02827589209382721

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An allometric relationship between foliage biomass and crown surface area is investigated in a data set consisting of 54 fertilized and 99 unfertilized Scots pine(Pinus sylvestrisL.) trees from 16 stands in Central Sweden. The allometric ratios for the unfertilized trees are shown to be weakly correlated with competition defined as tree height relative to dominant height (r= 0.475), and with crown coverage (r= ‐0.563). A slight level difference in the ratios can be detected between stands of different site moisture index. The overall relationship is nonlinear but becomes linear if the coefficient of proportionality is made dependent on stand average crown coverage. This also improves the percentage of explanation, which suggests that the allometry of the crown is related to the light conditions of the tree. Under fertilization, the relationship between foliage biomass and crown surface area seems less stable, at least if measured shortly after fertilization.

ISSN:0282-7581    

DOI:10.1080/02827589209382722

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor