Henry Chandler Cowles
and
Succession
Benjy Longworth
4/26/12
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
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•
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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
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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
Embryonic dunes
Wandering dunes
Stabilized dune
Impact of
vegetation on
physiography
Xeric, sunny, windy, sandy
Impact of
physiography
on vegetation
Mesic, shaded, less windy,
soil
View of Succession
• Succession =
mesophication process
• Shallow pond
succession
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
“Succession is a variable approaching a variable, not a constant.”
- Cowles 1901
Equilibrium
Holistic
Dynamic
Reductionist
Relay Floristics Model
• Only one set of species can colonize at a time
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
Initial Floristics
Hibbs 1983
• Model of succession depends on study system
• Connell and Slayter 1977
Facilitation
Neutral
Inhibition
Alternative Successional Pathways
• Impact of land use early establishment
Mesquita 2001
Alternative Pathways
7 years
-2.5
-1.5
2.5
2.5
2
2
1.5
1.5
1
1
0.5
0.5
0
-0.5
-0.5
0.5
1.5
-2.5
-1.5
-1
-1
-1.5
-1.5
-2
-2
-1.5
2
2
1.5
1.5
1
1
0.5
0.5
0
-0.5
-0.5
1.5
0
0.5
1.5
-2.5
-1
-1.5
-0.5-0.5
0.5
1.5
-1
-1.5
22 years
0.5
2.5
2.5
-2.5
0
-0.5-0.5
12 years
-1.5
-2
Blue= Vismia
Green = Cecropia
-2
17 years