190 ILLINOIS STATE ACADEMY OF SCIENCE 



trogression-causing activities, there progression of the 

 vegetative succession has been resumed. The potentiaUty 

 of the region for advanced stages of the vegetative suc- 

 cession has remained unchanged, except in so far as the 

 activities of man may have permanently altered this. Those 

 dealing vi^ith genetic plant geography M^ould probably all 

 agree that the glacial ice advance was a catastrophic event 

 in the history of vegetation. To a lesser degree, but to how 

 much less is uncertain, the advent of white men and their 

 brief stay of less than a hundred years in this region has 

 been absolutely catastrophic in its effect upon the native 

 vegetation. Not the speed of the reaction chiefly but the 

 degree of the effects is important. And it has been prac- 

 tically wholly retrogressive. It must be remembered that 

 here the discussion is concerned wholly with matters of 

 plant life separate from all economic questions. The eco- 

 nomic desirability of the proper handling of woodland 

 growth, of grazing, and so on, is, of course, absolutely un- 

 questionable. 



There are many evidences in the Rock River woodland 

 region of the disastrous effects on the native vegetation of 

 the clearing of wooded areas. On the west side of the Rock, 

 in the upland timber soils especially, gullying is so common 

 in farm fields that frequently makeshift measures to stop 

 or reduce the damage are encountered. It is of common oc- 

 currence on both the west and the east sides of the river 

 to find during the summer many small streams with dry 

 beds, streams giving evidence in the nature of their cutting 

 and in the dead or passing vegetation of their banks of hav- 

 ing once been fairly permanently watered. Then, too, in 

 a few places, where such small streams are still protected 

 in their flow by wooded areas, they are found with running 

 water throughout the summer. It seems certain that, al- 

 lowing for all natural exaggeration in the early accounts, 

 in the early days of white settlement and for unknown 

 years before that time the prairie fires were a factor of 

 prime importance in the development of the native vege- 

 tation of the region. The early records of Ogle County are 

 one with the records of similar sections of the country in 



