Ecological Responses of an Oligotrophic Floodplain Forest to Harvesting

Aerial and ground-based harvest systems were compared in terms of effects on gaseous and hydrologic transfers of N and P. The South Alabama study sites were narrow floodplains of low order, blackwater streams and were dominated by P-deficient histolsols and a mixed deciduous, evergreen forest. There was no statistically significant harvesting effect on either denitrification or surface and groundwater chemistry. Denitrification exhibited a strong seasonal trend and considerable within-site variation with annual rates ranging from 7 to 20 kg/ha per yr. Nitrate and phosphate concentrations in waters were quite low and did not vary significantly between the harvested zone and unharvested forests immediately upstream and downstream from the harvest. An unexpected result of the harvests was a statistically significant lowering of groundwater tables, an apparent evaporation response to elevated temperatures in the dark-colored organic soils.