33 



Originally the forests completely covered the bottomlands and about 

 58 per cent of the uplands. About 63 per cent of the entire region was 

 forested. At present 6.9 per cent of the uplands have forests, represent- 

 ing in area 13.4 per cent of the area originally forested. 



This type extends over 8,600 square miles, and variation in the forest 

 is consequently to be expected. Throughout this region the upland for- 

 ests are of two rather distinct types, the post oak associations on the 

 level lands (type 1), and the upland hardwood association on the slopes 

 (types). 



The post oak flats have a light gray soil and a very tight subsoil. On 

 the poorest soils post oak (Q. stcllata) may grow pure or associated with 

 black-jack oak {Q. marilandica) . Improved drainage conditions bring 

 black oak, shingle oak, and hickory associated with the post oak. In the 

 basins within these upland flats, where moisture collects but where the 

 subsoil is somewhat more pervious, pin oak often grows. The repre- 

 sentation of species by per cents, as given in the tabulation, page 1 1. based 

 on measurements of stands totaling 5.01 acres in five counties, is as fol- 

 lows : post oak, 73. 8 ; scrub oak, 11.9; hickory, 7.4; black oak, 5.1; 

 shingle oak, .9 ; and pin oak, .5. On these soils all of these trees have 

 a low growth-rate, and the stands usually have a great number of stunted, 

 bushy trees to the acre. At 100 years, post oak averages 56 feet in height 

 and 14 inches in diameter at the stump on these poor soils. Occasional 

 trees may attain a height of 65 feet and a diameter up to 30 inches, but 

 such trees represent defective and gnarled veterans upwards of 300 years 

 old. (Plate VI, Figure 1.) Ordinarily the stands appear decadent 

 at 100 years and do not produce trees of sawlog size. Sawlogs have 

 been harvested from virgin stands ; but such forests contain comparatively 

 few trees to the acre, such trees are over a century in age. and the prod- 

 uct is of low quality. This combination of the very long period required 

 to grow sawlogs, the low yield per acre secured, and the inferior quality 

 of logs, makes sawlog production on post oak sites a very unprofitable 

 undertaking. 



Throughout this region the coal mines use large quantities of small 

 timber in the round for props, legs, bars, and mine ties. Seventeen 

 counties of this region produce 73 per cent of the coal mined in Illinois. 

 Eased upon an average wood consumption for mine timbers of .246 cubic 

 foot per ton. the mine timber consumption for this region was 14,438,753 

 cubic feet in 1921. A cubic foot of standing timber in the trees of the 

 class from which mine timbers are produced will yield .74 cubic foot of 

 mine timbers. Hence the consumption of 14,438,753 cubic feet at the 

 mine is equivalent to 19.511,830 cubic feet of standing timber. 



The annual growth per acre, for 14 plots in post oak stands taken in 

 this region, varied between 9 and 24 cubic feet with an average of 15.8 

 cubic feet. The product of the entire 386,418 acres of forested upland 

 in the post oak region, if fully stocked, would supply about 31 per cent 

 of the mine requirements. The mines draw upon the Ozark bottomlands 

 and uplands as well as on the post oak region for material. 



