REGROWTH AND NUTRIENT ACCUMULATIONS FOLLOWING WHOLE-TREE HARVESTING OF A MAPLE OAK FOREST

The rates of biomass and N, P, K, Ca, and Mg accumulations were measured in a mixed hardwood-Haplorthod ecosystem following whole-tree harvesting and compared with preharvest conditions. Stand biomass and net primary production averaged 150.7 Mg/ha and 7.3 Mg.ha-1.year-1, respectively, in the preharvest forest. An estimated 100 Mg/ha of biomass was removed in a commercial whole-tree harvesting operation during the dormant season. Regrowth during the 4 years after harvest was categorized into the following floristic groups: woody plants, woodland herbaceous species that were part of the preharvest forest, early successional species that colonized the site after harvest, and graminoids. Woodland herbaceous and woody species dominated the recovery vegetation and together accounted for more than 70% of the nutrients captured by vegetation throughout the postharvest measurement period. Extensive clonal structures for many woody species and two common woodland herbaceous species, Pteridium aquilinum (L.) Kuhn and Aster macrophyllus L., resulted in their rapid recovery. Rapid growth along with high nutrient concentrations (especially K for woodland herbs) provided effective mechanisms for conserving nutrients following disturbance. After the first growing season following whole-tree harvesting, 44% of the total aboveground dry weight was in woody vegetation, 46% in woodlands herbs, 9% in early successional species, and 1% in graminoids, compared with 73, 17, 7, and 3% for the same categories by year 4. Annual rates of N, K, and Mg uptake by plants should equal or exceed their preharvest rates within 5 years after harvest; those for Ca and P take longer.