Silva Fennica vol. 10 no. 3 | 1976
Category : Article
The aim of the study was to determine which characteristics of tree stands could be used in urban noise control and to develop guidelines for practical urban forestry. The attenuation of artificially produced noise was measured in various types of stands. The effect of tree stands on noise attenuation has been analysed using a model based on the physics of sound propagation.
The results show that the excess noise attenuation caused by trees can be in good situations 60% measured in energy units, compared with the attenuation caused by geometric spreading. This is 5–8 dB. The total amount of needles, leaves and branches of a stand proved to be the most important factors in noise attenuation. However, the density and height of a stand had rather high value in predicting the behaviour of noise in tree stands. Based on multiple regression between noise attenuation and tree species composition, density and height of a stand it was developed the nomograms with which the noise level at a certain point can be predicted when the tree stand characteristics, the distance and the noise level of the noise source are known and on the opposite way.
The PDF includes a summary in Finnish.
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Kellomäki,
E-mail:
sk@mm.unknown
- Haapanen, E-mail: ah@mm.unknown
- Salonen, E-mail: hs@mm.unknown
In the study the proportion of branch samples of various diameter were studied. The branches were taken from small trees to be harvested by total tree chipping method. The material consisted of 1,056 branch samples of birch (Betula verrucosa, now B. pendula Roth, and Betula pubescens Erhr.), Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) at intervals of 20 cm along each branch.
With exception of the basic density of bark, there was a relation between all the other properties which were studied and the diameter. Even when the effect of diameter was eliminated, in many cases the effect of the distance of the samples from the stem became apparent.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The paper describes a method for the measurement of basic density of total tree chips. In the method the chips are placed in a container, which is immersed in a cylinder full of water, and the container is weighted at two levels. In the upper part of the cylinder the pressure against the air bubbles is smaller than in the lower level. In this method, the effect of air bubbles in the result can be eliminated. Besides this, due to homogenization of the material to be measured only small number of samples are needed for the estimation of the average basic density.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The paper deals with variation in the nitrogen, phosphorus, potassium, calcium and magnesium content of vegetation and soil of young Scots pine (Pinus sylvestris L.) stand of Vaccinium site type situated in Central Finland. The material consists of sequential samples representing soil, ground vegetation and trees taken during summer 1974.
The amount of soluble nutrients in the humus layer decreased in June when maximum growth of trees and dwarf shrubs occurred. The nutrient content of this layer subsequently began to increase towards the end of the growing period.
The variation in the nutrient content of the bottom and ground layers followed a similar pattern. Nitrogen content increases at the beginning of the summer. After this phase it started to decrease and reached its lowest values by the end of growing period. Phosphorus and potassium content increased throughout the growing period.
The nutrient content of the needles and wood were positively correlated with tree height and negatively with the age of material. The highest values for the nutrient content were for new cells.
The PDF includes a summary in English.
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Lehtonen,
E-mail:
il@mm.unknown
- Kellomäki, E-mail: sk@mm.unknown
- Westman, E-mail: cw@mm.unknown
The purpose of this study was to gain an insight into research problems and themes in multiple use of forests from a practical viewpoint. An inquiry concerning multiple use problems was sent to 597 organizations whose work related to multiple use of forests. Replies yielded 1,857 suggested research themes which were divided between different uses of forests. About half of the suggestions concerned the relations between timber production and the other uses of forests. The many propositions are due to the fact that timber production in its intensity has strong influence on the other uses of forests. The results of the study have been used in the planning of research in the multiple use of forests.
The PDF includes a summary in English.
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Saastamoinen,
E-mail:
os@mm.unknown
- Heino, E-mail: jh@mm.unknown
This paper analyses the nutrient loses caused by whole-tree harvesting on the basis of the literature data. It has been considered that traditional stemwood harvesting does not lead to impoverishment of the soil because the nutrient content of the wood is quite low. The nutrient loss occurring in connection with heavy thinnings and whole-tree harvesting has been considered so great that it has to be compensated by fertilizer application. In comparison with harvesting unbarked stem timber, whole-tree harvesting has been found to increase the nutrient loss at the stage of final cutting as follows: N2 to 4 times, P 2 to 5 times, K 1.5 to 3.5 times and Ca 1.5 to 2.5 times. Depending on the conditions prevailing on the site, any one of these nutrients may be the limiting factor for tree growth during the next tree generation
The PDF includes a summary in Finnish.
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Mälkönen,
E-mail:
em@mm.unknown