Planting density and silvicultural intensity: impacts on taproot, soil, and forest floor carbon and nutrients in the Lower Coastal Plain and Piedmont and Upper Coastal Plain in the southeast USA

This research investigated the effects of initial planting density and silvicultural intensity on taproot, mineral soil, and forest floor carbon (C) and nutrients. Total taproot and 5-50 mm diameter root C contents of 34 sampled trees were negatively affected by increasing planting density. Stand level estimates of taproot C, however, were not affected by planting density. Taproot biomass was higher in the LCP than in the PUCP. Taproot nutrient concentration increased with decreasing root diameter. Planting density did not have an effect on soil or forest floor mass, C, or nutrient concentrations. There was an increase in forest floor mass and C with more intensive culture, but this effect was not evident on soil C. Increased culture increased N in forest floor but not in soil. These results suggest that the use of high planting densities within intensively managed forest stands may not affect belowground C pools despite growing more aboveground biomass with increasing density. This is positive in that C and nutrient pools are not declining and may be sustained through multiple rotations.