The effect of selected forest defoliators on mortality rates and crown conditions in hardwood stands on the Allegheny National Forest (Pennsylvania)

From 1985 to 1995, Allegheny hardwood forests experienced a rise in tree mortality. Over 85% of the Allegheny National Forest (ANF) has been defoliated at least once since 1984. Forest Inventory and Analysis (FIA) and Forest Health Monitoring (FHM) data for the ANF were used along with aerial survey data to compare stand characteristics in defoliated and non-defoliated stands. A GIS was used to map the FIA and FHM plot locations and the defoliation polygons for each pest of interest. The percent standing dead basal area and percent crown dieback for host tree species were compared inside and outside of defoliation polygons for each insect pest. Several significant relationships were identified between frequency of defoliation and other stand and tree characteristics.