Greetings Cheryl:
There are two principal state forestry programs available in Illinois: Forestry Development Act (FDA) and the Conservation Stewardship Program (CSP).
The Forestry Development Act is tailored to "timber growers" who are interested in managing their forest lands for timber production in addition to other stewardship goals such as wildlife, recreation, soil and water conservation, and aesthetics. Minimum acreage requirement is 10 acres. This program offers the unique tax assessment of 1/6 the equalized assessed value as cropland. Yes, you may reserve one acre for a future home site; thus, you would enroll 39+/- acres into FDA. Length of program participation is variable; though you can cancel your FDA participation at any time (there are some minor stipulations such as receipt of state cost-share assistance and no-cost seedling from the state nursery).
The Conservation Stewardship Program is a program tailored to the more preservation-oriented landowner. In contrast, the tax assessment on CSP eligible lands is 5% fair market value.
For additional information regarding the CSP program, please visit:
http://dnr.state.il.us/Stewardship/instructions.html
For additional information regarding forest land tax assessments, please visit:
http://tax.illinois.gov/Publications/Pubs/Pub-135.pdf
Best of luck!