Twelve of the highest-quality woodlands in the northern two-thirds of the state were evaluated in this valuable study - along with thirteen savanna, barrens, and shrub-prairie remnants. Details of savanna and woodland classification and evaluation are discussed. This study had not been available on line. It is posted here so it could contribute to the revival of interest in such nearly lost "hot-spots" of biodiversity. These 25 areas were some of the best and last of their kind. It would be good to determine what has happened to them since 1996.
Bowles, M. and J. McBride. 1996. Report to the Illinois Department of Natural Resources, The Morton Arboretum, Lisle, Ill.
It can be reached through this link.
Fire-maintained oak savannas were one of the most common vegetation features of northern Illinois, but rapidly disappeared with settlement and fire-protection. Using a broad definition of 10-80% canopy cover, the Illinois Natural Areas Inventory (INAI) found few, if any, “high quality” examples of savanna vegetation. Since completion of the Inventory, numerous savannas have been reported, but have not been systematically inventoried for inclusion on the INAI. We evaluated over 40 northern Illinois sites on silt-loam and gravel substrates for inclusion on the INAI as savanna (10-50% canopy cover), woodland (50-80% canopy), or shrub prairie (<10% canopy). Ordination of canopy tree importance values allowed classification of savannas and woodlands along a dry, dry-mesic, mesic, and wet-mesic moisture continuum indicated by Quercus velutina, Q. alba, Q. rubra, & Q. bicolor, respectively. Quercus macrocarpa- and Q. ellipsoidalis-dominated savannas and woodlands also occurred on dry-mesic and mesic silt-loam and gravel soils.
This study was funded by the Illinois Department of Natural Resources.
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