Evaluation of a Method of Conversion of Clear-cutting High Forest to Selection Forest

1991

S. 911-919

11 Lit. Ang.

Unselbständiges Werk

200062072

Selection systems have contributed to a biological appreciation of forests and influenced management systems in the Czechoslovak forests. The principles of selection system were also applied in the School Forest Enterprise at Krtiny, University of Agriculture. The managed set of forest stands onverted to a selection forest created a demonstration, semi- operational and verification object, mainly with respect to the purposes of the existence of school forest enterprises. When the Forest Management Plan was prepared, it was decided that, besides the forest management based on the method of age classes, these stands will be treated by suitable checking methods. Implementing this decision, a project of stand management was worked out where the forest stands would be converted to selection forest by checking methods; Truhlar is the project author. Truhlar (1975, 1977) described in detail the requirements for the selection of forest stands of the operational set subjected to conversion to selection forest, for forest division, and management guidelines. Test stand 44C is located at the above- sea height of 440-505m in the oak-beech vegetation zone. Check plots were established ineach test stand to investigate changes of biometrical parameters. In stand 44C there is check plot no. 2 of 0.20ha and check plot no. 3 of the size 0.25ha. Measurements on these plots were performed in 1973 and 1986. Curves of diameter frequencies are used to determine wood yield and to regulate the volume of cut wood in particular diameter classes. Tree frequency is expressed as a function of the breastheight diameter, using a natural exponential function after H.A. Meyer in form of (Formel). The curve of type E (coefficients Alpha = 0.075, Kappa = 102.1, maximum breast-height diameter 73.6cm, tree number 405, basal area 30.3 Quadratmeter) was chosen for the forest stands of the School Forest Enterprise (Truhlar, 1975). In the years 1973-1986 the total loss of trees from 925 to 760 per 1ha was recorded on check plot no. 2. The highest loss occurred in spruce: in 1973 there were 815 trees per 1ha, but in 1986 it was only 660. In larch the number of trees decreased from 70 to 60 individuals per 1ha. A comparison in the diameter classes indicated a decrease in the tree number in diameter classes of 10, 14, 18, 22, 26 and 34cm, and an increase in diameter classes of 30, 38, 42 and 46cm. There is a general tendency of greater tree numbers in higher diameter classes. Although the tree number decreased, the total growing stock increased from 331 Kubikmeter to 402 Kubikmeter per 1ha. In comparison with the model curve of diameter frequencies, the approximation of present data was recorded if compared with previous measurements. In 1973, there were more trees in the diameter class of 34cm and less trees in the diameter class of 38cm in comparison with the model tree number, in ....