4 



is a wide variation in estimates of the total area of present woodland: 

 according" to the U. S. census, there are 9,?31 acres; the State Crop 

 Survey gives 2,173 acres ; and the Natural History Survey reports 6,400 

 acres. Probably not over one per cent of the county now bears any kind 

 of forest. This shrinkage in area of the woodlands of the county has 

 been accompanied by very great changes in their character. The present 

 forests are largely composed of trees which have come up since the set- 

 tlement of the country and, under conditions quite different from those 

 which influenced the character and composition of the virgin stands, they 

 are even-aged and dominantly oak. 



"The Big Woods" was a much more extensive forest than was 

 usually found near the headwaters of streams in this region. It was 

 situated within ten miles of the source of the Salt Fork of the Vermilion 

 River, at the bend of this stream where in its southern course it is turned 

 eastward by the Champaign morainic system, and occupied, in the general 

 form of a triangle, an area of about ten square miles. The southern side 

 of this wooded area was at about the present Main Street, Urbana, the 

 apex was some five miles up Salt Fork at a point opposite Leverett, and 

 the main upland forest extended down-stream another five miles to a 

 point north of Mayview. These woods were in places three miles across. 

 The eastern boundary of the original forest was about half a mile east 

 of the present woods. The existing remnant of the "Big Woods" occu- 

 pies the S. E. 34 °f Section 34, R. 9 E. Tp. 20 N. The general topography 

 of this 60 acres is that of a moderately rolling upland. The most pro- 

 nounced topographic feature is a small valley or swale extending diagon- 

 ally from the northwest to the southeast corner, through which drains 

 an intermittent stream. The total relief between the highest and lowest 

 part is about thirty feet, and the area is thus assured good drainage. If 

 cleared, probably three quarters of it could be cultivated without serious 

 erosion resulting. The soil along the swale, approximating a fifth of 

 the total area of the woodland, has been classified by experts from the 

 University of Illinois Agricultural Experiment Station as a brown silt 

 loam of the prairie; that of the adjoining rolling uplands, as a yellow 

 gray silt loam of the upland timber series. Both the swale and the ad- 

 joining uplands were timbered when the settlers first visited the region. 

 The largest tree on the tract, a bur oak having a diameter of sixty-five 

 inches at a distance of 4}/£ feet from the ground, is growing in this swale. 

 Such a tree requires approximately 250 years to attain this size, and it 

 was probably 150 years old when the first settlers arrived. In view of 

 the discussion among ecologists as to the factors controlling progression 

 of forest in encroaching upon the prairie,* it would appear that an ex- 

 amination and study of the tree and soil relationships in this particular 

 area might be instructive. 



The Brownfield Woods are of interest as a sample of the type of 

 forest which existed on the uplands of the upper Wabash drainage basin. 

 They are situated in the extreme northwestern margin of this area, yet 

 show the great variety of species which characterize the forests of the 

 Wabash region. The tree associations or types vary somewhat in response 

 to varying moisture conditions of the soil. The uplands and moderate 

 slopes adjoining bear a rich variety in which hard maple is the common- 

 est tree. Along the miniature bottoms elm predominates, but the tvpe 

 lines are not sharply drawn and elm may be commonly found on drier 

 sites. A complete record of the number of tree species in this woodland 

 has never been made. The University Woods, another fragment of the 



* See (1) in foot-note on following page. 



