202 ILLINOIS STATE ACADEMY OF SCIENCE 



ADVANTAGES OF RIVER CANYONS FOR 

 ECOLOGICAL STUDY 



Frank Thone, University of Chicago 



The dunes of Lake Michigan have long since become 

 classic soil to American botanists. They were early 

 recognized by taxonomists of a former generation as 

 collecting grounds unsurpassable for richness and va- 

 riety of flora. Under the eye of Cowles {1) they became 

 the cradle of ecology upon this continent, and the start- 

 ing-point of the whole successional idea. Fuller {2, 3), 

 a pioneer in the quantitative study of physical factors of 

 the environment, carried on his work here. And latterly 

 Cowles (4) again has made them a point of departure in 

 a significant essay in floristic history. 



It is only natural that the dunes should have become a 

 great outdoor laboratory of botany. Their relatively 

 great topographical relief, their restless and rapid 

 changes of position and surface, with erosion and de- 

 position going on simultaneously within radii of a few 

 yards, their relations to significant recent geological 

 events, all conspire to bring together in one place a most 

 remarkable diversity of environmental factors, and there- 

 fore also a group of plant communities notable alike for 

 their clean-cut character as ecological associations and 

 as floristic groups. 



The botanical advantages they offer, their topographi- 

 cal unity and geographical continuity, and the fact that 

 they have furnished the material for so many well-known 

 pieces of research, have rather tended to make the dunes 

 an overshadowing fact in middle-western botany. It is 

 the object of the present paper to bring out the point 

 that they do not present a unique and isolated phenome- 

 non in an otherwise dull and commonplace stretch of 

 country. Rather they are simply outstanding and criti- 

 cal features in an entity much larger than themselves, an 

 entity that has many other features just as critical though 

 less outstanding, which, nevertheless, await and will re- 

 ward scientific investigation. 



