Silva Fennica : quarterly issues : 30(2–3) : sa3023315.htm

Timo Kuuluvainen, Antti Penttinen, Kari Leinonen & Markku Nygren. 1996.

Statistical opportunities for comparing stand structural heterogeneity in managed and primeval forests: an example from boreal spruce forest in southern Finland

Silva Fennica 30(2–3): 315–328

The horizontal and vertical stand structure of living trees was examined in a managed and in a primeval spruce-dominated forest in southern Finland. Tree size distributions (DBHs, tree heights) were compared using frequency histograms. The vertical distribution of tree heights was illustrated as tree height plots and quantified as the tree height diversity (THD) using the Shannon-Weaver formula. The horizontal spatial pattern of trees was described with stem maps and quantified with Ripley’s K-function. The spatial autocorrelation of tree sizes was examined with semivariogram analysis. In the managed forest the DBH and height distributions of trees were bimodal, indicating a two-layered vertical structure with a single dominant tree layer and abundant regeneration in the understory. The primeval forest had a much higher total number of trees which were rather evenly distributed in different diameter and tree height classes. The K-function summaries for trees taller than 15 m indicated that the primeval stand was close to complete random pattern. The managed stand was regular at small distances (up to 4 m). The semivariograms of tree sizes (DBH, tree height) showed that the managed forest had a clear spatial dependence in tree sizes up to inter-tree distances of about 12 meters. In contrast, the primeval spruce forest had a variance peak at very short inter-tree distances (< 1 m) and only weak spatial autocorrelation at short inter-tree distances (1–5 m). Excluding the understory trees (h < 15 m) from the analysis drastically changed the spatial structure of the forest as revealed by semivariograms. In general, the structure of the primeval forest was both horizontally and vertically more variable and heterogeneous compared to the managed forest. The applicability of the used methods in describing fine-scale forest structure is discussed.

Keywords
boreal forests, Norway spruce, spatial analysis, K-function, semivariance, structural variation, biodiversity

Addresses
Kuuluvainen, Leinonen and Nygren, Department of Forest Ecology, University of Helsinki, PO Box 24, FIN-00014 Helsinki, Finland; Penttinen, Department of Statistics, University of Jyväskylä, PO Box 35, FIN-40351 Jyväskylä, Finland. Fax +358 9 191 7605, E-mail timo.kuuluvainen@helsinki.fi

Received 4 September 1995 Accepted 19 June 1996
ISSN 0037-5330

Comments