Henry Chandler Cowles and Succession

1. Henry Chandler Cowles andSuccession Benjy Longworth 4/26/12

2. Outline • Biography • Cowles’ work • Plant succession since Cowles • relay floristics vs. initial floristic composition

3. 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

4. Main Contributions • Pioneered ecology in America • “Dynamic” approach to ecology • Described in detail the stages of dune succession • Autogenic vs. Allogenic

5. 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

6. 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

7. Ecological relations … • Dissertation became his most widely known publication • Stages of succession = distance from the lake • Described abiotic and biotic characteristics of each stage

9. cottonwood/poplar/basswood grasses/shrubs pine Noticed unique vegetation at different stages oak/maple

10. Embryonic dunes Wandering dunes Impact of vegetation on physiography Stabilized dune

11. Xeric, sunny, windy, sandy Impact of physiography on vegetation Mesic, shaded, less windy, soil

12. View of Succession • Succession = mesophication process • Shallow pond succession

13. 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

14. Contemporaries • Frederic Clements • Clements saw succession as a much more deterministic process than Cowles • Driven by facilitation (autogenic)

15. Clements • Directional change from one plant community to the next until arrival at the climax community Climax

16. Cowles • Made fewer generalizations • Found plant plasticity (presence at several stages) • Variable “climax” community Oak Maple

17. Plant succession since Cowles • Clements 1916 Relay Floristics • Odum 1971 Information theory • Egler 1954 Initial Composition • Connell and Slayter 1977 Equilibrium Holistic Dynamic Reductionist “Succession is a variable approaching a variable, not a constant.” - Cowles 1901

18. Relay Floristics Model • Only one set of species can colonize at a time

19. 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

20. Initial Floristics

21. Hibbs 1983

22. Model of succession depends on study system • Connell and Slayter 1977 Facilitation Neutral Inhibition

23. Alternative Successional Pathways • Impact of land use early establishment Mesquita 2001

24. Alternative Pathways 7 years 12 years 17 years 22 years Blue= Vismia Green = Cecropia