Paul Rothrock 

Indiana Native Non-Profit 
Organization 
Plant Society US. Postage 
P.O. Box 501528 Indianapolis, IN 
Indianapolis, IN 46250-6528 Permit No. 229 
Address Service Requested 

Naturalist Profile 
The Indiana Dunes: 
The Roots of Ecology in America 
By Paul Rothrock 
Since the last glacial ice receded off the Indiana landscape, stiff wind off 
Lake Michigan, periodic vegetation fires, and changing water levels have 
continuously shaped the Indiana Dunes. In addition, the northwest corner 
of Indiana is the meeting place of floras from northern forest, eastern 
hardwood forest, and tallgrass prairie. All of these factors make the Dunes 
an amazing laboratory for natural science. And yet, surprisingly, from the 
| vantage point of a dune ridge, on a clear day one can see the skyline of 
| Chicago to the northwest across Lake Michigan. 
In the 1890s, Henry Chandler Cowles, an energetic graduate student at 
the University of Chicago, decided to take advantage of the proximity of 
the Dunes for his Ph.D. research. After all, the many habitats were readily 
accessible from the city via rail. The result: Cowles launched modem 
ecological research in America and became the academic ancestor of 
generations of scientists. 
Cowles (1899) stated in his seminal paper that “the province of ecology 
is to consider the mutual relations between plants and their environment.” 
But the environment in which plants grow “is composed of a myriad of 
topographic forms [that pass] into one another by a series of almost 
perfect gradations.” Moreover these landscape features are dynamic, 
never twice alike. “Ecology is a study in dynamics” and the ecologist endeavors to discover the laws which govern these changes. 
To best investigate these laws one needed an environment where change was rapid but recurring over time, an apt description of the 
Indiana Dunes. Cowles’ ideas remain foundational in the study of ecological succession’ and had an oversized role in inspiring scientific 
careers. 
One of Cowles’ many insights into ecological succession was the role of vegetation, especially marram grass (Ammophila breviligulata), in 
forming new dunes. Sand grains blown across the beach by prevailing winds become trapped by plant stalks. As grains accumulate marram 
grass grows upward keeping pace with the accumulation of sand. Cowles’ essential insight was that this began the process of dune building. 
As this process played out over time, coupled with periodic changes in lake water level, new foredunes formed. Thus dune formations further 
away from shore are older. Moreover, these older dunes support woodlands (and completely lack marram grass), a clue that one community 
Marram grass (Ammophila breviligulata) building a foredune at the 
Indiana Dunes State Park. 
: Ecological succession is a series of progressive changes in the species that make up a community over time. 
Roots — continued on page 19 
