COMPOSITION AND DYNAMICS OF SPITLER-WOODS, AN OLD-GROWTH REMNANT FOREST IN ILLINOIS (USA)

Trees and coarse woody debris were inventoried in a 65-ha mesic oldgro wth forest located on Big Creek in Macon County, Illinois. Based on da ta from thirty 0.1-ha circular plots, trees greater than or equal to 2 cm dbh had an average density of 1,266 trees ha(-1), basal area of 30 .4 m(2) ha(-1), and stocking of 102%. Sugar maple and white oak had th e highest importance values. The size distribution of tree diameters f or all species was characterized by a negative exponential shape. Howe ver, the size distribution of oaks, which currently dominate classes l arger than 30 cm, was unimodal with peaks at 50 to 60 cm. Oaks appear to be declining in dominance as sugar maple increases, a trend further confirmed by analyzing crown class by species. The average volume of down wood greater than or equal to 10 cm in diameter was 81.2 m(3) ha( -1). According to Government Land Office records, the southern half of Spitler Woods was apparently open in the 1820s. No current significan t differences in density or basal area between northern and southern p lots were found, but coarse woody debris was higher on the southern pl ots. Observed values at Spitler Woods were generally within the range of those reported for other old-growth tracts in Illinois.