Ill 



Northern group, 61 counties 



From map, 32 counties 4.665,049 acres 



Actually compiled 3,928,101 



Difference 736,948 



or 15.797 per cent 



From map, 61 counties 8,656,683 



15.797 per cent 1,367,496 



Net area forested 7,289,187 



Southern group, J/l counties 



From map, 12 counties 2,308,838 



Actually compiled 2,086,931 



Difference 221,907 



or 9.611 per cent 



From map, 41 counties 9,182,288 



9.611 per cent 882,510 



Net area forested 8,299,778 



Total for state, area forested... 15,588,965 acres 



These original forests showed an unusual variety of species. The 

 gums, cypress, and similar subtropical trees grew in southern Illinois, 

 while tamarack, arbor vitae, and associated sub-arctic species could be 

 found occasionally in the northern part of the state. Between these ex- 

 treme zones grew the wealth of hardwoods dominantly oak in character 

 which reached their culmination for this continent in the lower Ohio and 

 Wabash valleys. This hardwood forest varied, for different sections of the 

 state, in species composing the stand and in the forms of trees. Thus in the 

 southern uplands the forests were continuous and show a greater variety 

 of species as well as a generally better growth for similar species than 

 in the northern upland stands. These southern forests were noted for 

 the high quality of the timber which they contained. In the northern 

 uplands the trees grew in open park-like formations, thinning in the ad- 

 vance toward the prairie to the fire-scarred and gnarled outposts. There 

 is evidence that the forests were constantly endeavoring to encroach 

 upon the prairie, hut that annual fires generating an intense heat in the 

 abundant grass-cover burned back the tree seedlings and served as a 

 check upon the advance of the forest. The pioneers describe the old 

 forests of the prairie counties as being stands of grove-like aspect border- 

 ing streams and thinning rapidly as the prairie was apjiroached. To- 

 ward the margin, the forest floor was carpeted with a dense growth of 

 seedling sprouts growing between the scattered old trees. These seedling 

 sprouts were killed annually by the fires. The forests in the lower Ohio 



