Disturbance History of Two Natural Areas in Wisconsin: Implications for Management

• Published in: Natural areas journal 2000-01, Vol.20 (1), p.24-35
• Main Author: Cook, James E.
• Format: Article
• Language: English
• Subjects: Canopy gaps; Coniferous forests; Environmental policy; Forest canopy; Forest conservation; Forest ecology; Forest fires; Logging; Maple sugar; Old growth forests; Overstory; Trees; United States; USA, Wisconsin; Wisconsin
• ISSN: 0885-8608; 2162-4399

A thorough understanding of the changes in a disturbance regime caused by European settlement of North America can contribute to better management of natural areas. Using multiple information sources, I investigated the disturbance regimes, since the time of vers tory establishment, in two Wisconsin natural areas. The objectives of the study were to determine if significant changes had occurred and to assess the relative importance of natural and anthropogenic disturbances. The two areas differ in overstory composition—one is white pine and oak dominated, whereas the other is largely composed of northern red oak and sugar maple. The current overstories became established over a 60+-year period beginning in the mid-1800s, prior to extensive settlement. A series of low-to moderate-intensity disturbances created canopy openings that led to recruitment of present canopy members. In New Hope Pines, the white pine/oak forest, a combination of logging, low-intensity fire, and natural disturbances resulted in peak establishment between 1891 and 1911. In the northern red oak/sugar maple forest, Haskel-Noyes Memorial Woods, all disturbances since 1850 were probably natural but did not include fire. A moderatly intense disturbance, probably wind, initiated the northern red oak cohort that currently dominates the overstory. Accordingly, fire suppression this century has not affected Haskel-Noyes, whereas its exclusion from New Hope Pines has reduced pine and oak establishment and allowed red maple to increase dramatically. The rate of canopy gap formation appears to have accelerated recently, though median gap sizes are relatively small—30 m² at New Hope Pines and 48 m² at Haskel-Noyes. Given the disturbance history of these two areas, it is highly probable that the current composition and structure will not persist under the current disturbance regimes. White pine and oak dominance at New Hope Pines could be maintained by judicious use of prescribed fire in conjunction with creation of canopy openings. Size class distributions suggest a strong successional trend toward sugar maple at Haskel-Noyes. A moderately intense disturbance that creates gaps greater than about 0.3 ha will be required to keep northern red oak at its current level of abundance. This study demonstrates the value of using many information sources to reconstruct and describe disturbance regimes and thereby provide valuable information to natural area managers.