Gap dynamics in Allegheny northern hardwood forests in the presence of beech bark disease and gypsy moth disturbances

To determine changes in gap dynamics over a 6-year period in forests affect ed by beech bark disease and gypsy moth infestations, we conducted line tra nsect surveys of gaps and gap makers in three Allegheny hardwood forests in central New York. Gap makers were defined as any trees whose death or loss of >50% of the branches caused an opening in the canopy, and were divided into three categories: decline (standing live trees with >50% branch loss), standing dead, and treefall. Total land area in gaps increased significant ly (p less than or equal to0.00) from 19.7 to 31.9% over the 6-years of the study. American beech (Fagus grandifolia Ehrh.) represented 52.4% of the g ap makers in 1990 and 1996. Of the total beech gap makers, 30% were decline and 53% wen treefall gap makers in 1990, but by 1996, only 8% were decline as compared to 76% treefall gap makers. In contrast, the majority of oak ( Quercus spp.) gap makers were standing dead in 1990 and 1996. Although the rate of gap formation slowed at the end of this study, the predominance of beech in the subcanopy and regeneration layers poses persistent challenges for forest managers. (C) 2001 Elsevier Science B.V. All rights reserved.