Assessment of spatial stand structure of hemiboreal conifer dominated forests according to different levels of naturalness

摘要

Ecosystem legacies, reflecting the management history traits, are visible in structural indicators of a forest stand. We assessed patterns of spatial forest structure by using individual tree indices based on the nearest-neighbourhood approach. Five different indices were quantified - species mingling, deadwood mingling, deadwood distribution, diameter differentiation and the uniform angle indices characterising the patterns that show the complexity and diversity of forests: the arrangement of tree dimensions, species and deadwood as well as tree positioning regularities. Managed Norway spruce (Picea abies) stands are remarkably more homogeneous in terms of occurrence and positioning of different tree species and dimensions when compared to unmanaged forests. Managed Scots pine (Pinus sylvestris) stands rarely show co-occurrence of living and dead trees and demonstrate lower dimensional variability than unmanaged stands. Trees are often quite randomly positioned; slightly regular positionings became evident in managed Norway spruce stands. Structural analysis confirm that large trees are particularly important in maintaining the structural diversity of forests. Forest management needs to integrate maintenance of important structural components and patterns into timber production for biodiversity conservation and sustainable forestry. Natural forests are indispensable source for reference structures in forest ecosystems.