Ten-year results from the long-term soil productivity study in aspen ecosystems of the northern Great Lakes region

Abstract

Impacts of organic matter removal and compaction on soil properties and productivity are reported from the first 10 years of the Long-Term Soil Productivity Study in Great Lakes aspen ecosystems. Organic matter removal treatments included main bole, total tree harvest, and total tree harvest with forest floor removal. Compaction treatments included minimal compaction, moderate, and heavy compaction. Treatments were replicated on a clay loam, silt loam, and loamy sand soils. Compaction treatments on all soils increased bulk density above preharvest levels. In most cases, bulk density at year 10 was still above preharvest levels. Total carbon, nitrogen, and cations showed little or no impact from treatment. Compaction and organic matter removal impacted aboveground productivity, however the responses were variable. Aboveground production declined on the loam soil with moderate and heavy compaction. Production increased with moderate compaction on the loamy sand and clay loam soils, but significantly decreased with heavy compaction on clay loam soil. Total tree harvest with forest floor removal reduced production on the loamy sand and loam soils, while it increased production on the clay loam soil. Results from this study suggest that heavy compaction and/or high organic matter removals are detrimental to sustaining forest productivity.