Defoliation and oak mortality in Southern New England

Abstract

Crown class and diameter of 4088 upland oaks have been monitored at 10-year intervals since 1927. Plots had three episodes of moderate to heavy defoliation: 1961-1964, 1971-1972, and 1981. Primary defoliators were gypsy moth, canker worm, and elm spanworm. Mortality peaked during the period of 1957-1967 when there were three years of defoliation. Mortality was higher for white oaks than red oaks, and higher for lower canopy trees than for upper canopy trees. Since the end of the multi-year defoliations in 1972, mortality rates for both species groups and all crown classes have fallen to pre-defoliation levels. Mortality was related to tree vigor for red oaks with higher mortality for slower growing trees. The longer term impact of multi-year defoliation events in oak dominated forests is to accelerate mortality of less vigorous oaks in the lower canopy and slower growing trees in the upper canopy.

Parent Publication

• Proceedings, 15th central hardwood forest conference

Citation

Ward, Jeffrey S. 2007. Defoliation and oak mortality in Southern New England. e-Gen. Tech. Rep. SRS–101. U.S. Department of Agriculture, Forest Service, Southern Research Station: 214-221 [CD-ROM].