This research investigated the use of band/bogie tracks and slash with forwarders to reduce soil impacts.

Two forwarders were each loaded with 16 m3 (13 tonnes) of logs. Each forwarder was driven with and without band tracks for 10 passes. One of the forwarders operated on forest soil at two different moisture contents (moist and wet) and the other on a 15 kg/m2 (3 lb/ft2) slash layer (moist soil). The degree of sinkage and compaction was measured after each pass.
With the forwarder operating on soil, the maximum rut depths after 10 passes reached with a band track was 0.23 m (0.75 ft) less (0.48 vs 0.71 m (1.57 vs 2.33 ft)) on wet soil and 0.18 m (0.59 ft) less (0.22 vs 0.40 m (0.72 vs 1.31 ft)) on moist soils. The band track influence on compaction varied.
The forwarder operating on the slash mat had lower rut forming and soil compaction levels. The study found that band tracks, and more importantly slash mats, were necessary for environmentally sensitive logging on the soils experienced at the study sites.
Please access the Croatian Journal of Forest Engineering for a detailed and more complete account of the research. Source: http://crojfe.sumfak.hr/