Soil Biogeochemical Response To Forest Growth, Development, and Harvest.

In several hundred long-term soil sampling experiments worldwide, how intensive soil management alters soil chemistry, fertility, and even mineralogy can be directly observed.  In a long-term South Carolina Piedmont study of the effects of rapid growth and harvest of a pine forest on a granite-derived and previously cultivated Ultisol, a variety of significant soil changes have been directly observed over the six decades, during which forest has succeeded cultivated crops.  Bioavailabilities of many mineral-based nutrients such as Ca, Mg, B, and Mn were rapidly depleted by the first four decades of rapid growth of the pine forest, while other nutrients such as K, P, Zn, and Cu clearly were not.  Soil short-range-order Fe responded over time like no other nutreint, increasing in surface soils far out of proportion to uptake and recycling.  Soil mineralogy, land-use history, and forest nutrient cycling help explain changes in nutrient availability over time.  Following harvest and pine replanting, soil and forest regeneration response depends on the conservation and recycling of the large quantities of nutrients accumulated in the previous forest’s O horizons and unharvested biomass left on site following harvest.  A review of harvest off-takes of nutrients between forest and crop management will conclude the presentation.