Soil ecosystem services in loblolly pine plantations 15 years after harvest, compaction, and vegetation control
Site productivity has long been identified as the primary ecosystem service to be sustained in timberlands. However, soil C sequestration and ecosystem biodiversity have emerged as critical services provided by managed forest soils that must also be sustained. These ecosystem services were assessed in response to gradients of organic matter removal, soil compaction, and noncrop vegetation control on the thirteen 15-yr-old sites of the international Long-Term Soil Productivity (LTSP) study located in North Carolina, Mississippi, Louisiana, and Texas in the Atlantic and Gulf coastal plains of the southern United States. Whole-tree harvesting without removing the forest floor reduced tree volume at one site while removing the forest floor to achieve maximum nutrient removals reduced stand volume by 7% overall. Conversely, soil compaction increased pine volume production by 10% overall. Vegetation control increased pine stand volume production by 46% overall. Mineral soil C storage in the surface 0.3 m was similar overall regardless of treatment. Soil compaction and organic matter removal did not alter overall woody species richness or Shannon’s Index of diversity. Overall, these results suggest that biomass harvesting and intensive organic matter removal from southern pine stands has limited and site-specific effects on three soil ecosystem services: timber volume production, mineral soil C storage, and woody plant diversity.