Articles containing the keyword 'koeala'

18 permanent sample subplots of the Swedish and the Hassian Forestry Institute, each measured in equal intervals for several decades, were divided into subplots of different size. An analysis of variance was calculated for every set of subplot size. The development of intraclass-correlations over years and over different sizes of subplots could be explained if three different correlations were assumed: soil-correlation, correlations from irregular distribution of the trees, and correlation resulting from competition. Intraclass-correlations were positive or negative depending on dominance of one or two of these correlations.

An explanatory simultation study of competitional variance showed the effect of the degree of competitional correlations on the variance of means of subplots of different sizes. If this coefficient was small, all variances of subplots means within the range investigated became larger than expected in experiments without competition, with larger coefficients the variances of means of the smaller subplots became smaller, those of larger subplots larger than expected.

Plots of medium or large size are probably optimal for long term experiments with forest trees, if all sources of costs in such experiments are taken into account.

The PDF includes a summary in English and Finnish.

• Stern, E-mail: ks@mm.unknown

The annual fellings and sales of pulpwood from the State Forests of Finland comprised 4.0–4.6 million m³ in 1955–1959. In order to improve the accuracy of the methods used in estimating the pulpwood stocks marked for felling, a pilot survey of 18 marked stocks was carried out in 1959. The stock area, average plot volume, variation of the plot volumes, size and shape of the plot and the distribution of the trees by diameter classes as factors affecting the precision have been studied in this paper.

The greater the mean volume of a plot the more homogenous is the structure of the marked stock. The same number of plots gives a better relative precision for the south Finnish marked stock than for the north Finnish ones, which are heterogenous and less valuable. Stocks smaller than 50 ha can often be estimated more advantageously by the strip method or visually than by the plot method. The proper size of plot in Southern Finland is 0.02–0.03 ha. In Northern Finland the plots should be larger due to the heterogenous stocks, about 0.05 ha. The shape can be either circular or rectangular. The former may be more practical and reliable in the field. The minimum number of sample trees is considered to be about 200 per 100 sample plots 0.03 ha in size.

The PDF includes a summary in English.

• Kuusela, E-mail: kk@mm.unknown