Nitrate variability in hydrological flow paths for three mid-Appalachian forested watersheds following a large-scale defoliation

摘要: [1] Nitrate (NO3−) leakage from forested watersheds due to disturbance is a well documented but not understood process that can contribute the degradation of receiving waters through eutrophication. Several studies have shown large-scale defoliation and deforestation events in small eastern United States cause immediate dramatic increases NO3− flux steams, with large differences recovery time. Water quality discharge data collected 1992 2004 following gypsy moth were used investigate hydrological controls on long-term three Shenandoah National Park, Virginia. During storm events, conventional two-component hydrograph separation conjunction an inverse solution technique was employed determine concentrations groundwater soil water. Following defoliation, declined exponentially distinct seasonal pattern. A rank-order relationship between rate constants associated exponential declines recession indicates control watershed for these defoliated systems. Comparisons deforested systems Hubbard Brook, New Hampshire, Coweeta, North Carolina, indicate are similarly present. Biogeochemical differences, however, need be considered account more attenuated observed No trend found model-derived water concentrations, which suggests presence some form limitation transformation nitrogen pool introduced during and/or reduced nutrient uptake tree mortality.