Trial of Elaboration of an Evaluation Method of the Number of Occurrence of Fox-Coloured Cawfly (Neodiprion pini Geoffr.) in Pine Plantations and Thickets

1988

S. 33-41

2 Tab., 7 Lit. Ang.

Unselbständiges Werk

200032690

Sylwan 1988 ; 132 (7), S. 33-41

In the paper the authors presented a new method of evaluation of the number of occurrence of fox-coloured sawfly (Neodiprion sertifer Geoffr.) at determining the number and size of sample areas, they followed the principles of the great area forest inventory. Observations were made in thickets and young plantations of total area amounting to 198.83 ha. The sample areas had the form of rectangles 4 x 5m (20 m2) and each of them represented 1 ha forest area. Obtained results have shown great differences in the number of larvae in individual areas from 8.000 to more than 220.000 ha. This can speak for the occurrence of the fox-coloured sawfly in concentrations. On the whole, observations were made in 32 forest areas, divided into two age groups: the first group - plantations up tp 4 years, the second group - plantationsolder than 4 years and thickets. Trees attacked by the fox-coloured sawfly were divided into 4 biosocial classes: Z I - predominant trees, with regular structure, Z II - trees with average growth and good development, Z III - suppressed trees with various anomalies and Z IV - trees damaged by deer. In plantations aged up to 4 years, the fox- coloured sawfly preferred trees from the first biosocial class, in older plantations and in thickets - trees belonging to the first and second biosocial class. With the aim of determining the correctness of adopted assumptions and obtained results, the authors calculated the mean error of the proportion of attacked trees. It took in both mentioned age groups low values and amounted in the first group to (Formel) and the second group to (Formel).