Undisturbed, forestlands are relatively stable, as evidenced by stands of long-lived tree species. A primary cause of accelerated soil erosion in forests is the construction and presence of roads. This condition is especially true in temperate forests. Roads capture shallow subsurface flow or small streams above road cuts and concentrate water into channels that were developed by less concentrated flow and energy. The result is eroded banks and channel bottoms as these channels adjust, and sediment is moved downstream. Consequently, downstream channels and reservoirs fill with sediment. The ecological consequence of this type of erosion is the destruction of aquatic habitat developed under conditions of lower frequency, less extensive, and less massive influxes of upstream sediment. The spawning habitat of anadromous fish and eels in the Pacific Northwestern United States is especially susceptible to damage from this type of erosion process. The resulting economic consequences are loss of infrastructure when flood waters overflow channels and damage roads and bridges, river and lake commerce channel maintenance, and reduced reserve pools for hydroelectric generation.
Relative to the impact of roads in forestlands, erosion resulting directly from logging practices disturbing the soil surface and plant cover is typically short term, ending with reestablishment of ground cover (grass and forbs). In North America, forest practices have become increasingly regulated since 1959 with the aim of reducing erosion, and efforts have been largely successful. Erosion from logging practices continues to directly impact ecological processes in equatorial/tropical regions. This is especially true where crops are planted in nutrient-poor laterite (Oxisol) soils following logging, and the soil is incapable of supporting vegetation for extended periods after it has been abandoned by agriculturalists. In these circumstances, the ecological consequences of the erosion are as much local as regional, with changes in upland plant communities and wildlife habitat.
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