Initial recovery of soil structure of a compacted forest soil can be enhanced by technical treatments and planting.

Highlights • Skidding machines reduced pore spaces and increased the bulk density of soil. • Chemical/mechanical treatments increased soil aeration and reduced the bulk density. • The root system of grey alder improved the soil aeration status of a damaged soil. • Active regeneration techniques accelerate the recovery of a compacted soil. Abstract Heavy harvesting leads to harmful soil compaction and negative effects of soil physical properties and rootability. We monitored the recovery of soil structure in a compacted forest soil, which had been treated with a combination of regeneration techniques (mulching, liming, planting of alder trees or a combination of those). Soil physical properties (relative apparent gas diffusion coefficient (D s /D 0), bulk density and the macropore volume) were measured in three successive campaigns, with two years between each, with fine root densities taken as a biological target variable. Distinct changes of soil physical properties were detected during the study period, mainly caused by the effects of the applied regeneration techniques. After four years, higher values of D s /D 0 and macropores indicated significant improvements of soil aeration in the topsoil. The deeper soil showed no distinct evidence of regeneration, regardless of the regeneration technique applied. However, rather a negative impact of mulching on soil physical properties was detected. The measured physical parameters, D s /D 0 , bulk density and macropore volume correlate highly with observed fine root densities. In the topsoil, root density increases with increasing soil gas permeability, while in the deeper horizons only few macropores are occupied by fine roots for gas exchange. [ABSTRACT FROM AUTHOR]