VEGETATION AND SOIL DEVELOPMENT IN PLANTED PINE AND NATURALLY REGENERATED HARDWOOD STANDS 48 YEARS AFTER MINING 1

Abstract

Restoration activities at the time of stand initiation can have lasting effects on subsequent recovery of stand structure and function. Here we compared several metrics, with an emphasis on soils, of structure and function in forest stands that had been planted with pine or remained unplanted, and had undergone primary succession over 48 years on mine spoils. These were also compared to reference sites in the adjacent forest, to test the hypothesis that the development of forest functional processes will differ between planted and unplanted sites. Areas planted to pine had a lower basal area, and lower soil and microbial respiration rates than did unplanted areas. Basal area of unplanted sites was comparable or higher than that of reference sites, suggesting that the natural succession of hardwood may lead to better long-term recovery than planting of pine. Differences in root biomass, along with corresponding differences in soil respiration, suggest that below-ground biomass production recovers more slowly than does above-ground productivity. Mined sites had a greater stock of phosphorus than did reference sites. The greater presence of earthworms on mined sites may speed up nutrient cycling, as indicated by faster cellulose decomposition. Additional keywords: carbon, mining, nitrogen, phosphorus, Pinus