Dynamic parameterization to simulate DIN export due to gypsy moth defoliation

A module of dynamic parameterization is added into the HSPF watershed software for simulation of dissolved inorganic nitrogen (DIN) export from forest associated with gypsy moth defoliation. It simulates a changing ecosystem following the breakout of defoliation, such as increasing mineralization and nitrification rates and soil temperature, and decreasing interception of precipitation, plant nitrogen uptake rate and evapotranspiration. These parameter values vary with the stages of a defoliation event, such as the progressive period, the peak period, and the recovery period, the simulated DIN export from a multi-occurrence defoliation area in Shenandoah National Park in Virginia, USA, is comparable with the observed data.

Keywords: forested watersheds, nitrogen leakage