Variation of the factors affecting soil bearing capacity of ditched pine bogs in Southern Finland

Abstract

Recent studies indicate that the most important characteristics affecting the bearing capacity of pine bogs are tree volume and the strength and moisture content of the uppermost layers of moss. From a forest operations point of view it would, therefore, be essential to understand to what extent these properties vary and what the possibilities are to predict these properties prior to operations. The aim of this study was to investigate spatial variation of a basal area, soil strength and moisture content, as well as their co-variation, of ditched pine bogs in Southern Finland. The basal area is at its highest close to the ditch and to certain extent decreases with increasing distance from the ditch. The mass of living roots logically had significant correlation with the shear strength. The relationship between the shear strength and the mass of living roots confirms the applicability of spiked shear vane as a reliable tool in assessing the bearing capacity of peat soil. Both the closest trees and distance to the nearest ditch are significant predictors of volumetric water content in the topmost peat layers.

Keywords:

• logging
• peatland
• trafficability
• tree harvesting

Acknowledgements

We thank Pauli Ala-Vataja, Hannu Autio, Jouni Bergroth, Jani Heikkilä, Lauri Hirvisaari, Jari Ilomäki, Hannu Latvajärvi, Ari Ryynänen for their fieldwork and Anneli Nuijamaa for her assistance in laboratory analyses.

Disclosure statement

No potential conflict of interest was reported by the authors.