Impacts of harvesting and postharvest treatments on soil bulk density, soil strength, and early growth of Pinus taeda in the Gulf Coastal Plain:: a Long-Term Soil Productivity affiliated study

At four sites in the Gulf Coastal Plain, mechanical whole-tree harvesting (MWT) removed more biomass and nutrients than hand-fell bole-only harvesting (HFBO). Soil compaction and loblolly pine (Pinus taeda L.) regeneration growth varied among sites. At one location, MWT increased soil bulk density by 0.1 Mg(.)m(-3), from 1.14 to 1.24 Mg(.)m(-3), with no effect on tree growth. At a second location, where bulk density increased by 0.1 Mg(.)m(-3), from 1.41 to 1.51 Mg(.)m(-3), pine growth was reduced significantly. Soil strength at 15-20 cm depth increased by 0.3-0.5 MPa at both locations. However, where MWT reduced pine growth, herbaceous weed control mitigated the effect. Fertilization with N and P, where P was limiting, increased pine growth irrespective of other treatments. Where P was not limiting, addition of a complete fertilizer reduced the mitigating effect of weed control. Bedding reduced soil compaction without improving early tree growth; however, bedding was not tested on the two sites where soil compaction appeared to be at critical levels. Broadcast burning increased survival but reduced pine growth irrespective of harvesting method. Our results suggest that the impact of intensive management on site productivity varies among sites, is potentially accumulative, and is subject to change over time.