This is due to logging....
One difference between clear-cutting and fire is that numerous standing dead trees usually remain after a fire. This is not so in a clear-cut where if trees are left they are scattered live trees. Dead trees reduce wind velocity and provide partial shade and habitat for some animals. Also, there are usually few patches of any species left within a clear-cut, particularly conifer species. Thus, there is less
chance for these types of trees to reseed the cut. The amount of above ground material removed from the site differs. With fire, some material is turned to ash and some leaves the site as gas and smoke. Particulate matter in the smoke mostly falls elsewhere in the forest.14 With clearcutting, more material leaves the site to be transformed into lumber, pulp and paper. When full-tree harvesting is used, trunk, top and branches are removed from the site. The advantage to leaving branches scattered over the site is that this material (which contains more nutrients than the trunk) eventually decays, then enriches and builds the soil. Whichever cutting method is used it is important to ensure that the time between harvests is long enough so that the nutrients and soils have time to rebuild to their former levels.27, 29 Conversely, logging tends to leave more soil material on the site than fire. Although this aids in the soil rebuilding process, heavy logging machinery often redistributes, ruts and compacts the soil.30, 31 Compaction is a problem because studies have shown that seedlings have greater difficulty growing in soils that have lost their natural aeration.29 In the Canadian boreal forest these problems can be somewhat mitigated if harvesting takes place when the soils are frozen.30 Over centuries one effect of the intense heat of wildfire is that rocks and boulders shatter and ultimately become soil.29 Logged sites that are rocky or have bedrock close to the surface do not gain this benefit. Severe fires also remove many fungi and insects, including tree pathogens, from the site. However, many microorganisms rapidly recolonize the site.29, 39 Finally, logging, unlike fire, requires roads. New roads, bring many impacts, including a change in the behaviour of some animals and greater hunting and fishing pressure.29
http://wildlandsleag...es, Logging.pdf