Spatial autocorrelation of tree attributes in naturally regenerated managed beech (Fagus sylvatica) forests in the Beskid Niski Mountains, southern Poland

Abstract

European beech (Fagus sylvatica L.) is a widely distributed forest tree species in central, southern and western Europe. In Poland it reaches the eastern limit of its natural range. The three forest stands selected for the analysis presented here are located in the Dukla Forest Inspectorate, southern Poland in the Beskid Niski Mountains. The measurement plots were rectangular, 0.35 ha each, established under homogenous conditions. The origin of all stands is natural and up to now they were thinned several times according to selective thinning method. The main tree species on each plot is European beech. In each stand (x, y) coordinates, the species, total heights of trees and their diameters at breast height were recorded. Total tree height, diameter, basal area and tree volume were considered as marks in statistical analysis. The aim of this paper is to find out the differences in the spatial autocorrelation of different tree marks as well as to explain the reasons for differences if they were observed. The empirical mark correlation functions in- dicated that there is a negative spatial correlation of all these marks in all three forest stands, i.e. trees close together tend to have smaller marks than the average in the stand. No significant spatial correlation was found for the tree heights. Diameter, basal area and volume show some correlation, but only in one stand a deviation test showed that the detected spatial correlation is significant. The mark variograms indicated that neighboring trees tended to have similar sizes.