GRADUAL AND SUDDEN FOREST CANOPY GAPS IN ALLEGHENY NORTHERN HARDWOOD FORESTS

To determine the importance of gradual tree death to gap dynamics in A llegheny 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, m eaning 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 numbe r of gaps. Another 18.6% of the gaps had mixed causes. American beech (Fagus grandifolia Ehrh.), which is subject to beech bark disease in t he study area, was the predominant gap maker, representing 52.4% of th e gap makers compared with 25.6% of the canopy trees. It is suggested that future studies forest gap dynamics include measures of gaps formi ng over a period of time, particularly in forests subject to decline a nd biotic diseases and in other forests where gradual tree death and s tanding dead trees are known to be important.