the Prairie Unit, 6 percent of the total land area is com- 
mercial forest land; in the Claypan Unit, 16 percent; and 
in the Southern Unit, 28 percent. Eight counties, Fayette, 
Fulton, Jackson, Johnson, Macoupin, Pope, Union, and Wil- 
liamson, each contain more than 80,000 acres of commercial 
forest. Pope County is the most heavily forested county 
in the State. It contains more than 139,000 acres of com- 
mercial forest land which covers about 57 percent of the 
total land area in the county. 
There are 110,000 acres of forest land that are not 
producing commercial timber crops. They represent less 
than 3 percent of the total forest area in the State. 
This is forest land that is either reserved from timber 
cutting, such as State parks and recreation areas, or 
incapable of producing industrial wood crops because of 
adverse site conditions, such as rocky outcrops and swamp- 
land. Though not producing timber for the market, this 
noncommercial forest land adds to the wildlife and recrea- 
tional resources of [llinois. 
The sampling error of forest land for the State is 
about 2.4 percent at one standard deviation. Commercial 
forest land has a similar error of 2.8 percent. Sampling 
error is greater for small areas such as survey units and 
counties than for the State as a whole. Forest areas 
smaller than 24,000 acres have an error in excess of 30 
percent. Although subject to large error, estimates of 
county areas represent the best available information and 
will serve as a guide for management of resources. 
This note presents part of the results of the second 
Forest Survey of Illinois conducted in 1961 and 1962 by the 
Forest Service of the U.S. Department of Agriculture, with 
cooperation from the Agricultural Stabilization and Conser- 
vation Service of the same Department; from the Forestry 
Division, Illinois Department of Conservation; and from the 
Department of Forestry, University of Illinois. Other 
reports will follow presenting additional statistits for 
the timber resource and its use. 
Burton L. Essex, research forester 
Lake States Forest Experiment Station 
St. Paul, Minnesota 
David A. Gansner, research forester 
Central States Forest Experiment Station 
Columbus, Ohio 
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