Logging and the environment

Impact of timber harvest. Logging impacts the environment in many

ways, the timber harvest itself, that is, the removal of trees from the forest, and secondly by the disturbance caused by logging operations. Removal of trees alters species composition, the structure of the forest, and can cause nutrient depletion. Harvesting also can lead to habitat loss, prominently in high-value, ecologically sensitive lands. Loss of trees adjacent to streams can increase water temperatures. Harvesting adjacent to streams can increase sedimentation and turbidity in streams, lowering water quality and degrading riparian habitat. Logging roads and operations increase the risk of colonization of forest areas by invasive exotics, especially in the eastern North American hardwood and western evergreen forests (see also Gypsy moth). Some of the most clearly noticeable effects of large-scale clear-cutting, including effects on stream corridors, has been seen in the American Pacific Northwest, where endangered salmon spawning and rearing habitat has been damaged. A forest managed primarily for wood production will typically consist of young, vigorous, fast-growing trees. Such a forest may lack areas with late-succession characteristics, including older trees, required by some species. Good forest management requires that such areas be set aside to protect species that may be rare or endangered. Roadbuilding for access to timber in frontier forests often opens up areas previously not accessible, which facilitates further development such as farming.

Impact of logging operations. Modern ground based logging operations require the use of heavy machinery in the forest. In some areas roads must be built which often causes habitat fragmentation and increased edge effect. The use of heavy machinery in a forest can cause soil compaction. Harvesting on steep slopes can lead to erosion, landslides, and water turbidity. Logging on saturated soils can cause ruts and change drainage patterns. Harvest activity near wetlands or vernal pools can degrade the habitat. Forest machines use oils which, if not handled carefully, can cause pollution.

These problems can be mitigated by using low - impact logging and best

management practices, which set standards for reducing erosion from roads. Damage to streams and lakes can be reduced by not harvesting riparian strips. Ecologically important lands are sometimes set aside as reserves.

Logging can also have positive effects on the environment by removing damaged or diseased trees or both, and opening up the canopy to promote growth of smaller, healthier trees. Branches, snags, and other non-marketable parts of the tree provide shelter for wildlife. Underbrush that would not otherwise grow due to lack of sunlight thrives, and is an important food source for browsing mammals. Select cutting can improve the forest and bring to market trees that would otherwise decompose. Technological advances in logging equipment are reducing ruts and soil disturbance. Processors and Forwarders with Caterpillar tracks or other designs to lower ground pressure help to reduce machine impact.

Дата добавления: 2015-11-16