Catastrophic Windthrow in the Presettlement Forests of Wisconsin

Abstract

Presettlement survey records for the state of Wisconsin (circa 1834—1873) reveal a widespread pattern of catastrophic windthrow. From these records, we have calculated that there were 51.8 separate patches (>1.0 ha) of complete canopy windthrow covering a total of 4828 ha annually within the region of the presettlement hemlock—northern hardwood forests, in the northeastern part of the state. The estimated return time for catastrophic windthrow at a site in this region is 1210 yr. Catastrophic windthrow was much less common in the forests of southern Wisconsin. Comparisons of the presettlement disturbance regime with contemporary climatological records suggest that catastrophic thunderstorms were the principal mechanism for large—scale windthrow in northern Wisconsin.