RELICT EASTERN WHITE-PINE (PINUS-STROBUS L) STANDS IN SOUTHWESTERN WISCONSIN

In southwestern Wisconsin, close to the southern limit of its range, eastern white pine (Pinus strobus L.) grows in isolated 0.25-2 ha stands on steep outcrops of sandstone of the Se. Peter formation and Tunnel City group. Palynological evidence shows that white pine has been regionally abundant since at least about 10,480 years ago. Results from this study indicate that white pine continues to be self-replacing in spite of competition by hardwood species that dominate on the better-developed soils. In six of eight stands, white pine regeneration in 1992 appears to be at least as successful as in 1947 when McIntosh surveyed the sites. Size structure analysis suggests differing degrees of reproductive success of white pine among stands. Site characteristics such as topographic setting, slope steepness, slope aspect and relative stand size are not the only factors influencing success of white pine regeneration; logging, grazing and browsing alter conditions at individual sites. These disturbance agents have replaced fire, which was the major form of disturbance before European settlement. Under contemporary environmental conditions and land use, white pine will probably continue to persist at the southern limit of its range in southwestern Wisconsin, although some individual stands currently show a decline in reproductive vigor.