Recent changes in an upland forest in south-central New York

Sixteen permanent plots in the Arnot Forest in upstate New York, originally surveyed in 1935 and resurveyed in 1985, were measured in 1993 and 1996 to examine recent changes in forest structure and composition resulting from tree mortality, growth and recruitment. Tree density (greater than or equal to 5 cm dbh) declined significantly forest-wide between 1985 and 1993 (1275 to 1079 stems/ha) in this ca. 110-yr-old, even-aged forest because the high mortality of several dominant species (especially sugar maple, American beech and basswood) was not matched by recruitment. A small but nonsignificant decline in basal area also was observed during this interval (31.7 to 30.5 m(2)/ha). During the interval from 1988 to 1993 tree mortality was significantly higher in the Arnot Forest than the earlier (1935-1988) and most recent (1993-1996) periods. This pulse of high mortality apparently affected nearly all species (with che notable exceptions of white ash and hemlock) and size classes, though the suppressed and largest size classes were most affected. Weather records for nearby Ithaca, NY indicated that an unusually severe drought occurred in early summer 1988 and the pulse of mortality may have been triggered by this drought.