A portable matting system mitigates soil disturbance caused by a mini forestry crawler

Climate change-driven disturbances of forest ecosystems such as bark beetle infestations have been counteracted with salvage logging resulting in vast clear cuts. During these operations, commonly used heavy machinery causes irreversible degradation of forest soils. Thus, traffic has been restricted to skid trails. However, the emerging trend of mechanizing manual work leads to an increasing application of remote-controlled mini forestry crawlers (MFC) on undisturbed forest soils. We present the first study simulating the initial traffic effects on soil physical properties and functions of a Cambisol caused by a light-weight, rubber tracked MFC, with and without using a portable matting system (PMS) for soil protection at unfavorable soil moisture content. Our data document that successive passes without PMS significantly intensify soil structural damage and cause deep reaching compaction. Even a PMS does not completely protect against negative effects on soil physical properties and functions. However, after five passes over the PMS, these effects corresponded to those of a single pass without PMS, but even 10 passes with PMS use did not lead to further soil degradation. Steering maneuvers caused the most intense soil compaction and deformation. The induced shear forces and machine vibrations could provoke a loosening of the topsoil and the formation of macropore-like crack structures. These structures will most likely increase the aeration and hydraulic conductivity of the damaged soil, but should not be misinterpreted as soil improvement. Hence, MFC traffic on undisturbed, moist forest soil should be avoided and cannot be recommended without using a PMS.