Impacts of wood extraction on soil: assessing rutting and soil compaction caused by skidding and forwarding by means of traditional and innovative methods

Elena Marra,Fabio Fabiano,Francesco Neri,Enrico Marchi,Giovanni Mastrolonardo,Andrea Laschi,Tomas Nordfjell,Cristiano Foderi

doi:10.1007/s10342-021-01420-w

Abstract

Intensive forestry operations may cause soil compaction, plastic soil disturbances and rutting, which are responsible for undesirable effects on soils, vegetation and water bodies. Despite the numerous studies aimed to identify the main factors affecting soil damages, it still remains unclear whether wood extraction methods and driving direction (uphill or downhill) may affect the impacts of forest machines. This research analyses soil compaction and soil penetration resistance as well as rutting from forwarding and skidding using the same farm tractor in up- and downhill wood extraction. Rutting was estimated by 3D soil reconstruction derived by portable laser scanning (PLS) and close-range photogrammetry using structure for motion (SfM). Our findings showed that the direction of extraction did not affect soil damage severity during forwarding on a 25% slope. On the contrary, in order to reduce soil compaction, downhill skidding is preferable to uphill skidding. The results showed that the pressure on the ground caused by vehicles can be distributed horizontally, thus affecting also the soil between the wheel tracks. The soil bulk density inside the tracks after 10 forwarding passes increased by 40% and with 23% between the wheel tracks. The soil displacement in skidding trails (7.36 m3 per 100 m of trail) was significantly higher than in forwarding (1.68 m3 per 100 m of trail). The rutting estimation showed no significant difference between the PLS and SfM methods, even comparing the two digital surface models (DSMs) obtained, even if photogrammetry was preferred for technical and practical reasons.

Highlights

Soil disturbance is an unavoidable consequence of timber logging, but the severity of its impact is variable and can be managed through good planning and practices (Ares et al 2005)
Solgi et al (2016) demonstrated that the soil compaction expressed as bulk density (BD) occurred as far as 1 m from the wheel ruts and increased with slope gradient and traffic intensity, which explains the differences in our results between undisturbed area and between the tracks (BtwR) in terms of BD
The main aim of this study was to describe the effects of wood extraction on both the physical properties of soil and the rutting caused by tractors with winch or trailer in different wood extraction directions

Summary

Introduction

Soil disturbance is an unavoidable consequence of timber logging, but the severity of its impact is variable and can be managed through good planning and practices (Ares et al 2005). Ground-based logging operations can negatively affect soil physical characteristics, reducing porosity while increasing bulk density and resistance to mechanical penetration (Siegel-Issem et al 2005; D’Acqui et al 2020; Lee et al 2020). Rutting and other soil disturbances can disperse pathogenic fungi, alter microbiological processes (Frey et al 2009; De Wit et al 2014; Cambi et al 2017) and mobilize heavy metals due to the increase in surface water flow (Frey et al 2009; De Wit et al 2014; Eklöf et al 2014). Depending on logging conditions (e.g. soil condition and type, wood extraction method, machine characteristics and operator skills), the surface affected by disturbance within the logging area may range widely from 10 to 87% (Spinelli et al 2010; Marchi et al 2014; Naghdi et al 2015)

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