372 A NATIONAL PLAN FOB AMERICAN FORESTRY 



Although cutting and fire have depleted the hardwood forests, 

 regrowth has taken place rather promptly. When the mature forest 

 has been destroyed, coppice and other new growth have taken pos- 

 session. Hardwood litter helps to increase soil fertility and porosity. 

 On hardwood areas, particularly in the rather rough country at the 

 head of the Chippewa River, the forest cover prevents erosion of the 

 fine soil that would easily be floated away. 



SILT LOAM UPLANDS 



Only about half the upland area was originally occupied by forests. 

 The most extensive of these forests were in southwestern Wisconsin and 

 northwestern Illinois, and in southern Illinois and southeastern 

 Missouri. The others existed as scattered areas of woodland in the 

 prairies and in the bottom lands. Toward its western edge the basin 

 was practically treeless. 



Some of the forests were exploited commercially. In the lead 

 region of northwestern Illinois and in the limestone areas, extensive 

 fuel-wood cuttings were made. Commercial timber production for 

 other than local needs prevailed in the bottoms, particularly in south- 

 ern Illinois. Although fires were a usual concomitant of cutting, 

 devastation was prevented by the fact that the forests were largely of 

 hardwoods which sprouted. 



In the prairie region, small areas of the scattered original forests 

 remained as farm woodlands. These have been repeatedly culled and 

 most of them have been pastured. Culling has left only the poorest 

 trees, and in many instances pasturage has grown so heavy as to 

 prevent tree reproduction. 



The upland soils were very fertile and very absorptive when first 

 put under cultivation, because of the accumulations 01 organic matter. 

 Agriculture gradually exhausted the humic deposits. Sheet erosion 

 increased as the humus was dissipated. On the hilly lands it soon 

 developed into small shoestring gullies, and these rapidly grew into 

 more serious gullies. 



Severe gullying took place wherever water collecting on the plateau 

 lands ran over the bluffs. It has now gone so far that on many hill 

 lands it prevents the farmers from reaching some of their fields with 

 farm equipment. 



INFLUENCE OF FOREST COVER ON WATERSHED CONDITIONS 



Because the silt loam soils of the uplands are eroded so easily when 

 bare, the forest cover on them is classed as having a major watershed- 

 protective influence. That a forest cover maintains favorable con- 

 ditions of water flow on these upland soils is shown by observations 

 of the Lake States Forest Experiment Station as to run-off from 

 summer rains in southwestern Wisconsin. 35 Data from these in- 

 vestigations show that the run-off from pastures that have been 

 cleared, plowed, and seeded, as well as from areas in timothy, 

 clover, or alfalfa, is approximately the same as that from cultivated 

 fields. Seeded pastures, because of close cropping, packing of soil, 

 and slopes generally steeper than those prevailing in fields, were the 

 largest contributors to run -off. 



3 5 Bates, C. Q., and Zeasman, O. R., Soil Erosion, Wisc.Agri.Expt.Sta.Res.Bul. 99, 1930. 



