Vegetation of Forest and Savanna Communities on Glacial Sand Deposits in Northeastern Illinois (Report‪)‬

Before Europeans entered Illinois, the proportion of forests to prairies had been changing continuously depending on climate and humanmade causes. When Europeans arrived, prairies covered ca. 60% of Illinois (Iverson et al., 1991). Most was black soil, tall-grass prairie of the prairie peninsula (Transeau, 1935), although deposits of sand with associated sand prairie and sand savannas were relatively common (Schwegman, 1973). These deposits of sand from glacial outwash are common in the northern one-half of Illinois, resulting from erosion associated with Wisconsian glaciation (Willman and Frye, 1970; King, 1981). These deposits account for nearly 5% of land in Illinois. The most extensive deposits are the Kankakee sand area in northeastern Illinois and the Illinois River area in the central part of the state. Pembroke Township is in the Kankakee Sand Area Section of the Grand Prairie Natural Division (Schwegman, 1973). This deposit covered parts of Iroquois, Kankakee, Grundy, and Will counties, Illinois, and adjacent Newton County, Indiana. A few studies of vegetation on the Kankakee sands have been conducted. McDowell et al. (1983) described composition and structure of savanna communities of the Iroquois County Conservation Area, and Johnson and Ebinger (1992, 1995) studied effects of fire on vegetation of the savanna at Hooper Branch Nature Preserve, Iroquois County, Illinois. The present study was conducted to determine composition and structure of communities of vascular plants, floristics, and changes in density of overstory using aerial photographs of five wooded communities on the Kankakee sands.