GRADUAL AND SUDDEN FOREST CANOPY GAPS IN ALLEGHENY NORTHERN HARDWOOD FORESTS

To determine the importance of gradual tree death to gap dynamics in Allegheny northern hardwood forests, line transect surveys of gaps and gap makers were conducted in three mature forests in central New York. Of the total number of gaps, 71.7% were classified as gradual gaps, meaning they were partial openings in the canopy caused by either trees with greater than 50% branch loss or standing dead trees. Sudden gaps, caused by trees that had fallen, constituted 9.7% of the total number of gaps. Another 18.6% of the gaps had mixed causes. American beech (Fagus grandifolia Ehrh.), which is subject to beech bark disease in the study area, was the predominant gap maker, representing 52.4% of the gap makers compared with 25.6% of the canopy trees. It is suggested that future studies forest gap dynamics include measures of gaps forming over a period of time, particularly in forests subject to decline and biotic diseases and in other forests where gradual tree death and standing dead trees are known to be important.