Lesson 12 - Alaska Geobotany Center

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Development of the American continuum view of plant communities:Gleason, Curtis, and Whittaker• Although Gleason was scarcely recognized at the time of his 1926 paper, mainly becauseof the dominance of Clementsian ideas at the time, he eventually had a tremendousinfluence on American plant ecology.• In the 1950 s, John Curtis and his colleagues at the University of Wisonsin developedmethods of indirect ordination of plant communities, whereby stands of vegetation wereorganized mathematically by the floristic similarity to each other. In the next 40 years,these mathematical approaches almost totally replaced methods of classification basedon table analysis.• About the same time that Curtis was working in Wisconsin, Robert Whittaker waslooking at vegetation along continuous elevation gradients in different areas of the USA.He also adhered to the continuum school of phytosociology, but he had a broader viewalso recognized the validity of the association approaches used in Europe. He edited aclassic book entitled Classification of Plant Communities which summarized theapproaches from many schools and attempted a synthesis of ideas.• In Europe, during this period, vegetation science was and still is dominated by theassociation approach of Braun-Blanquet.
Whittaker s data of tree species occurrence along moisture gradients in theSiskiyou Mountains, Oregon and Santa Catalina Mountains, ArizonaSiskiyou Mtns.Santa Catalina Mtns.• Show Robert Whittaker s data for the abundance of all tree species alongelevation/moisture gradients in two mountain ranges.• These data tend to support the view of Gleason. A number of other studieshave also supported this view.• Over the last 45 years, there have been heated debates between plantcommunity ecologists regarding whether the views of the associationapproach are valid at all.
Page 1 and 2: Lesson 12: Community concepts andat
Page 3 and 4: Flora vs. vegetation?
Page 5 and 6: Physiognomy• Physiognomic approac
Page 7 and 8: Dansereau s “lollipop diagrams”
Page 9 and 10: Raunkiaer s life forms based on pos
Page 11 and 12: Bioclimatic diagram showing distrib
Page 13 and 14: Plant Functional Types (PFTs)• It
Page 15 and 16: Plant Functional Types of Box (1981
Page 17 and 18: BIOME model (Prentice et al. 1992)
Page 19 and 20: Environmental constraints of the PF
Page 21 and 22: Vegetation redistribution of Europe
Page 23 and 24: Braun-Blanquet sorted Example table
Page 25 and 26: Simpson s and Shannon-Wiener s indi
Page 27 and 28: Alpha and Beta diversity• Whittak
Page 29 and 30: Phenology diagram for Acomastylis r
Page 31 and 32: Phenological diagrams ofin selected
Page 33 and 34: Productivity gradients• Fig. 8-7,
Page 35 and 36: Association Approach• Fig. 8-1, p
Page 37 and 38: Major proponents of the “discreet
Page 39 and 40: Clement s view• Clements, recogni
Page 41 and 42: Major proponents of the continuumap
Page 43: A broader view of Gleason: Nicholso
Page 47 and 48: European reaction to the “Anglo-A
Page 49 and 50: Summary• Some characteristics of

Lesson 12 - Alaska Geobotany Center

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