Recreation by its very nature is more or less elusive of definitions, for people want variety in recreation whether that be accomplished by a change of environment or by different forms of recreation. Tastes in recreation vary from bridge to pack trips in the wilderness; they include active recreation and spectator enjoyment.

It is generally recognized that plant growth is affected by the acidity of the medium in which the plant is grown. The relationships between pH and growth are not simple and need additional clarification. The bulk of evidence available in this field indicates that the indirect effects of soil Ph on plant growth are much more important than any direct effects, and it is at only the very high and very low pH values that plants are directly affected. Magistad (12), Wilson (24) and McGeorge (8) found that root injury was not obtained in culture solutions at pH values as low as those found in very acid soils.

Farm woods of the central hardwood region vary widely as to size and as to proportion of total farm area. On good Corn Belt land the woodland area within a county rarely averages more than 10 or 12 acres per 120-acre farm, but south of the glacial boundary the average rises in some counties to 30 or 40 acres per 80-acre farm. In many Corn Belt counties gross woodland area amounts to less than 5 percent; in many hill counties, it exceeds 50 percent. To focus this discussion, I have roughly estimated the average woods area on farms in different parts of the region as follows: