Current issue: 58(5)
Acta Forestalia Fennica vol. 30 | 1926
Category : Article
The article presents the principle of working if a dendrometer and the mathematical theory behind it. Dendrometer is a new measuring instruments used to determine the height and diameter of a standing tree. The usability of the instruments is proofed to be very good thought there are some limitations to its use.
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Lönnroth,
E-mail:
el@mm.unknown
The article presents some basic elements of soil frost and its occurrence. The data contains observations from different regions and soil types in Finland. Different forms of soil frost and factors affecting its formulation are discussed.
The article concludes with the factors effecting soil frost. There are three issues. By the single grain soils the water content determines whether the frost becomes massive or layered. The structure of soil determines the occurrence of hollow formed frost. Within the soils with crumb structure both layered and hollow formed frost may occur. Layered frost may occur in soils with homogeneous crumb structure in which two kinds of ice layers occur: irregular and solid. The hollow-formed frost may occur in locker soils.-
Kokkonen,
E-mail:
pk@mm.unknown
The mean has a great importance in statistics in general and also in forest statistical calculations. The meaning of the average tree and its characteristics is important also for the practical forest mensuration work. However, the question is how are the statistical numbers of a mean tree related to the statistical numbers of the stand.
Study is based on the strip-wise survey of forests in southern Finland. From that information the 30 sample plots were chosen, 10 of each of most typical forest site types, MT, VT and CT. The stands are of different ages and development classes, varying from 14 to 159 years.
For the determination of the average tree are the statistical numbers of five characteristics needed: volume, basal area, diameter, height and form factor. The stereometric mean tree of the stand can be calculated with only one statistical method and that solution is absolute.
Theoretically and statistically absolute solution for the problem is the continuous solution by the mean that is weighted with the number of stems. This solution however is not very useful in practical sense.
A simple, practical and adequately exact solution for determining the average tree by approximation procedure of a certain arithmetic mean.
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Lönnroth,
E-mail:
el@mm.unknown
Study is based on the strip-wise survey of forests in southern Finland. From that information the 30 sample plots were chosen, 10 of each of most typical forest site types, MT, VT and CT. The stands are of different ages and development classes, varying from 14 to 159 years.
The article discusses the earlier literature on the factors effecting forest stands and presents the data in detail. The results section is divided into paragraphs on number of stems of the stand, height, crown, breast height diameter, basal area and volume. The statistical numbers are calculated and presented.
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Lönnroth,
E-mail:
el@mm.unknown
