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and cordwood. The form of the trees is very good wherever the 

 density is great enough to encourage height growth, but those on the 

 poorer sites, such as exposed cliff sides and rocky ridges, are short 

 and gnarled. On the gentler slopes at the foot of the ridges the woods 

 have been opened up to allow of pasturing, and the result is a very 

 open stand of rather short-boled, large-crowned trees. Bur oak is 

 especially prominent in such stands. Many slopes have been cleared 

 unwisely, and erosion has resulted. The prevalence of grazing has 

 reduced reproduction, especially of seedling origin, and fire has been 

 frequent enough to kill much of the young growth. Insect infestations 

 have been rather extensive, especially among the hickories. 



Distribution of Tree Species 



The distribution of species is governed chiefly by climate and 

 physiography, but other less stable factors exert an influence, with 

 the result that exceptions can often be found to any general rules 

 that may be laid down. A species will occasionally be found entirely 

 out of its natural range, the seed coming from a cultivated specimen, 

 or through the travel of mankind. 



The southeast portion of Illinois, along the Ohio and Wabash 

 rivers, is the richest in number of species, and in this respect is not 

 surpassed, or perhaps not even equaled, by any region of the United 

 States. There are about one hundred different trees found in this 

 part of the state. The valleys of the other large rivers, such as the 

 Mississippi, Kaskaskia, Illinois, and Rock, also contain a great variety 

 of species. Toward the north, the number of species grows less, 

 although there are some, belonging to a more northern flora, which do 

 not occur at all in the south. Many southern lowland trees reach the 

 limits of their normal range along stream valleys, as such situations 

 afford shelter and favorable sites on which to grow. On the other 

 hand, others, such as bur oak, which in the south ordinarily grow 

 on wet situations, extend northward on higher, better-drained sites. 



The Illinois forests are composed almost entirely of hardwoods, 

 while conifers are few in number and generally restricted in occur- 

 rence. The only evergreens that grow throughout the state are the 

 two sparsely distributed species of juniper, one of which, the dwarf 

 juniper, is seldom more than a shrub. The only commercially impor- 

 tant native conifer is the bald cypress, which is found in the bottoms 

 of the Cache and Ohio rivers in fairly large quantities. In the south, 

 there is also the shortleaf pine, which is confined to small stands along 

 the bluffs of the Mississippi, from opposite Wolf Lake, in Union 

 County, to the southern borders of Jackson. In the north, white and 



