USDA Forest Service Northern Research Station, Research Paper NRS-17
Impacts of organic matter removal and compaction on soil physical and chemical properties and forest 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 no compaction beyond normal levels from harvest, moderate compaction, and heavy compaction. Main bole harvest with no additional compaction served as the control against which other treatments were compared. Study treatments were replicated in three locations on a clay loam, silt loam, and loamy sand soil. All compaction treatments on all three soil types increased bulk density above preharvest levels. In most cases, bulk density at year 10 had decreased significantly compared to year 0, but was still generally above preharvest levels. Total carbon and nitrogen showed no impact from treatment at year 10. In general, soil cations were little affected by organic matter removal. The major exceptions were lower near-surface calcium in the loamy sand soil with total tree harvest plus forest floor removal, and lower potassium at 10-20 cm depth in the loam soil for both total tree harvest with and without forest floor removal. Compaction and organic matter removal treatments impacted aboveground forest productivity, however the effects were not universal across the soil types. Aboveground biomass 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 the 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 (e.g., total tree harvest plus forest floor removal) are generally detrimental to sustaining forest productivity across soil types. Total tree harvest with limited compaction may be sustainable, at least as reflected in 10 year results, after one harvest entry. Managers should be cautious of approaches involving whole-tree harvests, or even bole-only harvests, on short rotations (~10 years), as such approaches will limit the potential for recovery to preharvest bulk densities and may have the potential to increase compaction to levels seen with heavy compaction.
Voldseth, R.; Palik, B.; Elioff, J. 2011. Ten-year results from the long-term soil productivity study in aspen ecosystems of the northern Great Lakes region. USDA-FS Northern Research Station, Research Paper NRS-17