Effects on soil physical characteristics after forwarder passes for logging operations

The most important problem of the forest sector is to minimize the ground damage caused by heavy forestry machines during forest operations. Generally, harvesting effects include changes in; vegetation, nutrient availability, soil microclimate and structure, and litter quantity and quality. Several studies were carried out on the impacts of heavy machinery on soil. However, only a few studies took into consideration the effect of bogie tracks on soil impact. The aim of this research was intended to investigate how a bogie track can influence the soil compaction through changes of the soil physical parameters (bulk density, porosity shear and penetration resistance). The study was carried out in a conifer stand of Larix decidua and Picea abies in one forest in north-eastern Italy during logging with a forwarder. In this site 3 tracks (of 20 m) were identified, 2 influenced by loaded forwarder passes and 1 control (no passes). The tracks were: (i) track A, with 31% of slope and influenced by 2 passes, and (ii) track B, with 3% of slope and influenced by 10 passes. Soil samples after forwarder passes were collected on all tracks in order to directly determine how the forest operations influenced the various soil physical properties. The results showed different impact of logging operations on soil between tracks.