Effects of different logging practices on soil density and root mass

Abstract

Any movements of forest machines under the forest canopy are harmful for the stand. Their tracks and wheels damage the soil surface: strip off the litter, disturb the sequence of horizons, alter soil hydro-physical properties. These impacts affect the root content of soils. Especially sensitive in this sense is the spruce, whose roots are mostly concentrated in the topsoil which is disturbed by vehicles. To address the problem of stand damage, it is essential to wisely choose the logging technology and machinery. The widely used practices in Karelia are tree-length skidding by crawler tractors, as well as cut-to-length harvesting. The study aimed to assess the effect of various partial cut practices on soil density and the mass of spruce roots up to 3 mm thick in the middle taiga of Karelia. Soil density was studied in skid trails and in the interior of forest blocks not accessed by machines; root masses were compared. The method of soil monoliths sampled from skid trails and blocks throughout the logging area was used. Cutting to length by machines (harvester + forwarder) was found to cause the heaviest topsoil compaction, as compared to mechanized cut-to-length harvesting (chain-saw + forwarder) or tree-length skidding. Root mass in the trail and inside the block, where machines did not reach, remained different for 12 subsequent years whichever practice was used. The difference was the greatest in the first several years after logging. Soil density in the trail recovered at a faster rate than the root mass.

Keywords

• soil density
• root mass
• logging machinery
• operation technology
• partial cut