DEMOGRAPHY OF OLD-GROWTH WHITE PINE STANDS AT THE HURON MOUNTAIN CLUB RESERVE AND ESTIVANT PINES IN UPPER MICHIGAN

摘要

Few old-growth white pine (Pinus strobus) stands remain in the Upper Midwest after the lumbering era. White pine shows poor recruitment in mature mesic stands. Long-term studies are needed to examine succession in these forests and the ability of white pine to reproduce. I established permanent plots and examined forest demography in two preserved forests in Upper Michigan. Adjacent 1.54- and 0.92-ha plots in the Huron Mountain Club Reserve included a white pine-hemlock (Tsuga canadensis)-hardwood forest and an atypical white pine-white spruce (Picea glauca) stand with dense undergrowth of sugar maple (Acer sacchamm) saplings. At Estivant Pines a 0.78-ha plot contained a stand of white pine-sugar maple-balsam fir (Abies balsamea), while a second 0.75-ha plot held a similar stand with large gaps. All stems > 5 cm dbh were measured and mapped and small saplings (1-4.9 cm dbh) were tallied in transects. Only the Huron white pine-white spruce stand showed a broad size distribution of white pine trees (but no saplings) that indicated dominance well into the future. White pine trees in the other plots were virtually limited to large emergents above a maple or hemlock canopy. Only the Estivant gap site contained a number of white pine saplings but theseface competition with eight other sapling species to reach the canopy. Future results in these long-term permanent plots will track the ability of white pine to persist in these forests, to see if small gaps or other factors allow episodes of reproduction without a major disturbance.