Reduced ground disturbance during mechanized forest harvesting on sensitive forest soils in the UK

Description/Abstract

Field trials were undertaken in north-east England and south-west Scotland to investigate the degree and nature of disturbance on selected forest soils during mechanized harvesting, where extraction routes were armoured with a layer of logging residues (slash roads). Dry soil bulk density, soil strength (soil penetration resistance) and saturated hydraulic conductivity, measured directly beneath the machine wheel tracks on gleyed mineral and deep peatland soils (peat >45 cm deep), exhibited only minor changes despite high levels of trafficking. This was ascribed to (1) the role of the slash roads in reducing machine ground pressures; (2) the inherent strength and elastic recovery of the overlying fibrous peaty soils, retained in situ as a result of the slash roads; and (3) the slow rates of densification associated with the underlying saturated fine textured mineral soils. In addition, the slash roads were observed to improve vehicle traction and efficient carriage of timber to roadside log landings. This study demonstrated that disturbance on peaty or fine-to-medium textured mineral soils at high water contents can be largely avoided, allowing operations to continue during periods when wet ground conditions may otherwise limit harvesting.