Soil compaction under timber harvesting machinery: a preliminary report on the role of brash mats in its prevention

Mechanized timber harvesting machinery causes considerable soil damage and compromises future forest soil sustainability. The viability of using harvesting residues (brash) placed over machinery traffic areas to protect soil was studied at Kielder Forest, U.K. Various thicknesses of brash mats were tested for their performance in reducing soil compaction in a gley soil. Penetration resistance and dry soil bulk density were measured before and after passes with timber harvesting machinery over the brash mats. Soil under even the thickest brash mats showed some compaction to at least a 45 cm depth, but compared to bare soil, the mats provided some protection against compaction. The potential for brash mats to have an adverse effect on the establishment and stability of future tree rotations is not clear.