On the Consequences of Using Moving Window Segmentation to Analyze the Structural Stand Heterogeneity and Debatable Patchiness of Old-Growth Temperate Forests

Abstract

(1) Background: Early research in natural forests on decennia implanted conviction concerning the patchy patterns of their structural heterogeneity. Due to the variety of methodological approaches applied, verification of this fundamental assumption remains open. The aim of this study was to discuss the methodological limitations associated with the use of moving windows with overlap for the delineation of homogeneous patch mosaics in forest ecosystems. (2) Methods: The “patchiness” hypothesis was tested in six old-growth forests formed by Abies alba Mill., Fagus sylvatica L., and Picea abies (L.) H. Karst. localized in Bosnia and Herzegovina and southern Poland. In each stand, the tree diameter at breast height (dbh) was recorded on circular sample plots of 154 m2 regularly distributed in a 20 × 20 m lattice over an area of 10 ha. (3) Results: Computer simulations showed that patch classification based on overlapping windows results in apparent patchiness, even for completely randomized tree distributions. Analyses carried out on the empirical data indicated prevalent random patterns of structural heterogeneity. (4) Conclusions: Patchiness is not a universal feature of the investigated forest communities. The size of the moving window and the noise-smoothing procedure exert strong effects on the biasedness of patch classification, the frequency of structural types, and the mean patch size.

The Strong Position of Silver Fir (Abies alba Mill.) in Fertile Variants of Beech and Oak-Hornbeam Forests in the Light of Studies Conducted in the Sudetes

“…As Vrška's et al [54] research suggests, the historically recorded changes in the shares of beech and fir in fertile lowermontane forests in large areas of the Carpathians are principally attributable to changes in forest management. However, this does not mean that periodical changes in the shares of beech and fir that occur locally in relatively small areas are not natural in character [3,[55][56][57][58][59][60]. If the natural crop rotation referred to above is a common phenomenon, this means that the operating cycle of fertile lower-montane forests may be more complex than we thought and longer than 300-400 years.…”