CRADLE-KNOLL PATTERNS AND CHARACTERISTICS ON DRUMLINS IN NORTHEASTERNWISCONSIN

Cradle-knell microtopography has been shown to influence soil and vege tation. However, the scale of commonly used topographic maps is too co arse for representation of microtopography. The objectives of this stu dy were to investigate the influence of cradle-knell microtopography o n the distribution of trees, to develop a method to quantify the spati al patterns and characteristics of cradle-knolls, and to test for patt ern similarity of cradle-knells within and among drumlins in the Nicol et National Forest, Wisconsin. Six drumlins were selected for study. T ree species, tree diameter, and microsite location (e.g., cradle, knel l, or neither) within which each tree was found were inventoried in th ree, 10-m-radius plots across each drumlin. The spatial location, leng th, width, relief, and orientation of 220 cradle-knells were inventori ed along 200-m transects using a T-square sampling technique on summit and backslope positions of each drumlin. Sixty percent of the trees i nventoried were growing on knells and only 2% were growing in cradles. The same number of knells and cradles occurred among drumlins and amo ng backslopes and summits within drumlins. Cradle-knell relief differe d among drumlins, and knell relief is greater on backslopes than on su mmits within drumlins. Cradle-knell orientation differed among slope p ositions. These findings suggest that treethrow rates and the size of the uprooted trees are roughly the same among and within drumlins. Dif ferences in relief among drumlins are probably an indication of how re cently treethrow has occurred. Greater relief of knells among backslop es and summits is probably because of slope-mediated differences in cr adle-knell formation. Slope position also affects cradle-knell orienta tion in these landscapes.