The dunes as a field site
Cowles completed his doctoral thesis in 1898 using fieldwork in the Indiana Dunes. Related research appeared in Botanical Gazette in 1899. He compared vegetation across the landscape to investigate community change.
Inferring change from a landscape
Mobile lakeside dunes supported beach vegetation, while more stable dunes contained cottonwoods, pines or oak forests. Cowles inferred that stabilization, accumulating organic matter and altered microclimates could permit replacement by other plants.
References: [2]
Physiography and field teaching
His 1901 study of Chicago and its surroundings extended this approach to other environments. He later emphasized field teaching, taking students across North America; Victor Shelford was among the ecologists influenced by his teaching.
An evolving theory of succession
The dune studies became an important case in succession research. Subsequent work examines disturbance, migration, resources and climate, rather than assuming every community must follow one inevitable path to a permanent forest.
References: [2]