Variability of tree characteristics and sample size planning for forest inventory in pure Sessile oak stands

Abstract

From the aspect of statistics and dendrometry, forest stands, as specific sets, are observed as sets of trees or sets of elementary areas of different shapes and sizes. Planning the sampling size for measurement of forest estimation elements is based on the variability study of major estimation elements in our forests. Research variability of tree characteristics in pure mature sessile oak stands, showed that out of the basic tree characteristics, volume increment of trees has the highest variability. The height variability is the lowest. In the mature sessile oak stands, i.e., stands where it is necessary to begin the process of re-establishment of forest cover, high accuracy of volume assessment is necessary. Greater accuracy of the estimate of mature stands volume is much more necessary than the estimate in the middle and young stands. Starting from the data for 20 pure sessile oak stands (age class VII) and using the multiple regressions, the model for evaluating the coefficient of variation of tree volume was obtained. Based on the number of trees and the basal area of the stands, the coefficient of variation of tree volume is obtained. Starting from the regression model, it is possible to determine the necessary sample size for forest inventory, for the required accuracy of the estimate.