Effects of disturbance on nitrogen export from forested lands of the Chesapeake Bay watershed

The objective of this research project is to develop, test, validate, and d emonstrate an analytical framework for assessing regional-scale forest dist urbance in the mid-Atlantic region by linking forest disturbance and forest nitrogen export to surface waters at multiple spatial scales. It is hypoth esized that excessive nitrogen (N) leakage (export) from forested watershed s is a potentially useful, integrative "indicator" of a negative change in forest function which occurs in synchrony with changes in forest structure and species composition. Our research focuses mainly on forest disturbance associated with recent defoliations by the gypsy moth larva (Lymantria disp ar) at spatial scales ranging from small watersheds to the entire Chesapeak e Bay watershed. An approach for assessing the magnitude of forest disturba nce and its impact on surface water quality will be based on an empirical m odel relating forest N leakage and gypsy moth defoliation that will be cali brated using data from 25 intensively-monitored forested watersheds in the region and tested using data from more than 60 other forested watersheds in Virginia. Ultimately, the model will be extended to the region using spati ally-extensive data describing: 1) the spatial distribution of dominant for est types in the mid-Atlantic region based on both remote sensing imagery a nd plot-scale vegetation data; 2) the spatial pattern of gypsy moth defolia tion of forested areas from aerial mapping; and 3) measurements of dissolve d N concentrations in streams from synoptic water quality surveys.