Investigations of the Effect of Defoliators on the Increment of Fir Forests

Wien

1974

10 Lit. Ang.

Unselbständiges Werk

673

200144708

Many Silver Fir (Abies alba Mill) forests in Yugoalavia were subjected to various defoliators. The most dangerous is the Fir needle moth (Argyresthia fundella F.R.). The defoliators destroy the needles of the trees and so they reduce the assimilating apparatus. Therefore I was interested to invastigate how does the reduction of assimilating opparatus affect the increment. As the object of my research I choose the management unit "Belevine" in the Gorski Kotar region in Croatia. In order to be able to give an answer to the query, I put the Silver Fir trees in different groups: 0%, 10%, 20%, 30%, 40%, etc. where 0% means the trees with full crown; 10% means the trees with the crown reduced by 10%; 20% means the trees with the crown reduced by 20% etc. From each Fir tree was taken one increment core-in total 326 cores. After the analysis of cores and after the statistical processing of data we obtainad the following result: the reduction of assimilating apparatus by 10% caused a drop of diameter increment by 25%; the reduction of assimilating apparatus by 20% caused a drop of diameter increment by 30% etc. The investigations should be continued in other forests in order to be able to establish a code.