198 



wherever scattered seed-trees have been left after lumbering. Pin oak 

 is less abundant on the Mississippi, where it has been very closely cut 

 for fuel wood. It naturally diminishes in numbers toward the north 

 and is rare beyond Dallas City. Silver maple, white elm, cottonwood, 

 and willow predominate where the oak is lacking, and usually form 

 dense stands. White elm is the chief tree on drier situations, and 

 maple on the wettest flats. There is very little merchantable timber 

 left, and a comparatively large amount of it is on the Illinois, where 

 a lumberman familiar with the territory estimates that there is about 

 15,000,000 board feet of all species from Chillicothe to the mouth of 

 the river. 



TABLE V. — Showing Estimated Percentage of Species in Bottomland 

 Type of Northern Illinois, by Counties. 



On the Illinois River and its tributaries much timber has been 

 killed by the flooding which has followed the opening of the drainage 

 canal. In addition, the ordinary insect and fungus enemies that thrive 

 in heavily cut-over and neglected forests have done their work. Elm 

 and ash are especially subject to insect injury, while pecan and ash 

 are liable to be damaged by a dry rot. Elm and sycamore are likely 

 to be decayed, at least at the butt. Pin oak, while more free from 

 disease than the others, is somewhat liable to wind-shake. 



Sand Dunes. — Exceptions to the general forest type found in the 

 bottoms of the Mississippi and Illinois rivers are the sand plain and 

 sand dune formations from about Burlington, Iowa, to Savanna on 

 the Mississippi, and from Florence to Pekin on the Illinois River. 



