Site preparation burning to improve southern Appalachian pine-hardwood stands: aboveground biomass, forest floor mass, and nitrogen and carbon pools
Prescribed fire is currently used as a site preparation treat-ment in mixed pine-hardwood ecosystems of the southern Appalachians.Stands receiving this treatment typically consist of mixtures of pitch pine (Pinus rigidu Mill.), scarlet oak (Quercus coccinea Muenchh.), chestnut oak (Quercus prinus L.), red maple (Acer rubrum L.), and dense under-stories dominated by mountain laurel (Kulmia lafifoliu L.).Abusive land practices such as high grading and grazing, in combination with drought-induced insect (southern pine beetle) infestations, have left the stands with sparse, low-diversity, and slow-growing overstories. To improve the over-story composition and productivity of these ecosystems, the silvicultural prescription involves cutting all woody vegetation in early summer, burning with a high-intensity but low-severity fire in late summer, and planting white pine (Pinus strobus L.) on a wide spacing (i.e., 4 x 4 m). Burning facilitates planting and reduces mountain laurel competition with the planted seedlings. The desired future condition of the overstory is a productive pine-hardwood mixture, with white pine, which is resistant to southern pine beetles, as the dominant pine. The impacts of these treatments on nutrient cycling, productivity, and vegetation diversity are unknown. To determine these impacts, a long-term, multi-investigator study was established (Swift et al. 1993). The present paper addresses treatment impacts on aboveground mass and associated nitrogen (N) and carbon (C) pools.