Henry Chandler Cowles and Succession Benjy Longworth 4/26/12
Dec 30, 2015
Outline
• Biography
• Cowles’ work
• Plant succession since Cowles– relay floristics vs. initial floristic composition
Biography
• 1869-1939• Born in Kensington,
Connecticut• 1893 – BA from Oberlin
College • 1898 – PhD in Botany from
University of Chicago• 1899 -1934 – Faculty at U
Chicago until retirement • 1914 – Helps found
Ecological Society of America
Main Contributions
• Pioneered ecology in America• “Dynamic” approach to ecology• Described in detail the stages of dune
succession• Autogenic vs. Allogenic
A selfless career
• Few publications• Invested much of his time teaching– His largest impact may have been through the
work of his students (46/77 influential ecologists between 1900 and 1950)
• Also spent time advocating conservation• Research was very descriptive, no numbers in
his papers
Publications• 1899. The ecological relations of the vegetation on the sand dunes
of Lake Michigan. Botanical Gazette • 1901. The plant societies of Chicago and vicinity. Botanical Gazette • 1901. The influence of underlying rocks on the character of the vegetation.
Bulletin of the American Bureau of Geography• 1908. An ecological aspect on the conception of species. The American Naturalist• 1909. The Trend of ecological philosophy. The American Naturalist• 1910. A Textbook of Botany for Colleges and Universities. • 1910. The fundamental causes of succession among plant associations.
• 1911. The causes of vegetation cycles. Botanical Gazette• 1915. The economic trend in botany. Science• 1926. The succession point of view in floristics.• 1927. The persistence of praries. Ecology
Ecological relations …
• Dissertation became his most widely known publication
• Stages of succession = distance from the lake
• Described abiotic and biotic characteristics of each stage
grasses/shrubs cottonwood/poplar/basswood
pine
oak/maple
Noticed unique vegetation at different stages
Biotic succession (autogenic)• Process driven from within • Facilitation/Inhibition• Humus formation
– Water– Soil organisms– Temperature and aeration
• Shade
Topographic succession (allogenic)• Process driven from without• Create heterogeneity of succession• Disturbance due to erosion and deposition
Contemporaries
• Frederic Clements– Clements saw succession as a much more
deterministic process than Cowles– Driven by facilitation (autogenic)
Clements
• Directional change from one plant community to the next until arrival at the climax community
Climax
Cowles
• Made fewer generalizations• Found plant plasticity (presence at several
stages)• Variable “climax” community Oak
Maple
Plant succession since Cowles
• Clements 1916 Relay Floristics • Odum 1971 Information theory
• Egler 1954 Initial Composition• Connell and Slayter 1977
Equilibrium Holistic
DynamicReductionist
“Succession is a variable approaching a variable, not a constant.”- Cowles 1901
Initial Floristic Composition
• Egler 1954• Succession depends on the species that establish
initially• All species able to establish early• Different growth rates, life spans determine
succession
• Model of succession depends on study system• Connell and Slayter 1977
Facilitation
Inhibition
Neutral
Alternative Pathways
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7 years12 years
17 years22 years
Blue= Vismia Green = Cecropia