1. Henry Chandler Cowles and Succession 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. grasses/shrubs cottonwood/poplar/basswood pine oak/maple Noticed unique vegetation at different stages

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

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

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 Inhibition Neutral

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