Timber Harvest Effect on Soil

The overall effect is a small loss in total soil carbon; both total carbon content and concentration decrease in the "forest floor," but not in the surface or deep mineral soils. 

Black dots are total carbon; white dots are carbon concentration.

The decrease in total forest floor carbon is greater in hardwood forests, although there is some evidence that it takes longer to rebound in conifer forests because of their lower litter production.

Citation:
Nave LE, Vance ED, Swanston CW, Curtis PS. Harvest impacts on soil carbon storage in temperate forests. Forest Ecology and Management. 2010;259(5):857–866.