Soil disturbance caused by management activities such as timber harvests or fuels treatment, can affect the future productivity of a site. Until recently, it’s been assumed that forest soils require a long time to recover following a disturbance. However, the results of a 22-year soil monitoring study on the Kootenai National Forest in Montana demonstrates that certain types of forest soils recover within five to seven years following harvest operations and fuels treatments.
On 183 plots located within former harvest units, soil samples were collected from 1992 through 2006, and again in 2012-2013. The soil was categorized undisturbed, moderately disturbed, or heavily disturbed. After 22 years, 86 percent of the plots showed some sign of recovery, and there were plots that fully recovered. Even the ash-capped soils, which were thought to require more than 40 years to recovery, saw improvement. Most of the recovery was observed in the first five to seven years following the timber harvest and fuels treatments. Factors that contributed to a soil’s recovery were the freeze-thaw cycles, wet-dry cycles, and root growth, since all these both broke up the compaction; and whether the soil was prone to compaction.