Pushing the Limits of Forest Resilience
The Long-Term Soil Productivity Study was conceived in the 1980s by a consortium of concerned U.S. and Canadian scientists. Recognizing that properly functioning soil is a prerequisite for the health of all forested ecosystems, the scientists designed and installed a common experiment at more than 100 sites throughout the two countries to test the resilience of soils and forests following moderate-to-severe disturbance. The study's guiding principle was based on the assertion that forest productivity and health are governed by soil processes which are, in turn, readily affected by management. A series of treatments on clearcut land included combinations of soil compaction and partial or complete removal of nutrient-rich surface organic residues. The study asked whether critical changes in soil fertility and porosity have a lasting effect on forest vegetation and, if so, how would the effects vary across continental climates and soils? By 2015, most study sites in California had reached the 20-year mark, and the findings provided unanticipated evidence of forest soil resilience and recovery. Diagnostic soil properties such as carbon storage, nutrient content, root penetration, and water and air movement did not differ dramatically among treatments, and, of equal surprise, differences in tree growth response were ordinary. These findings support the concept that soil functions can remain robust following a one-time forest harvest disturbance of considerable severity.
Forest Service Partners