Textbook Notes (280,000)
CA (170,000)
UTSG (10,000)
BIO (600)
BIO120H1 (300)
Chapter 8

BIO120H1 Chapter Notes - Chapter 8: Westerlies, Superorganism, Plant Ecology


Department
Biology
Course Code
BIO120H1
Professor
Spencer Barret
Chapter
8

This preview shows pages 1-2. to view the full 7 pages of the document.
Tuesday, December 6, 2016
Struggle for Existence !
Part VIII: Community ecology, mostly plants
-Early plant ecologists!
used “stands” of vegetation (numerous study sites)!
made lists of plants they found there!
search for informative patterns in data!
argument with colleagues about meaning of patterns!
-Difficulties of plant ecology!
plant communities are pretty resistant to experimentation!
lacks a tradition of experimentation!
-experiments are either undervalued or hard to perform!
-Frederic Clements from Nebraska (~1900)!
pioneer of descriptive study of plant communities!
studied the remaining native prairie vegetation!
later studied other biomes as well!
believed that all sites on Ontario will result in beech-maple forests as a matter of
time (starting product/ influence doesn't matter)!
thought turnover as an autogenic process (recently known as facilitative)!
-one prevalent species changes the environment!
-emphasizes that environment is changed by the species themselves!
-the opposite of this is called “allogenic” (environment is changed by external
forces, NOT biotic community)!
interest: some plant species occurred together more often than one would expect
by chance (pattern association)!
-ex. if you can find American beech in a forest, you’ll probable find sugar maple
too!
1

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Tuesday, December 6, 2016
-theory: plant association occurs because the species were functionally
dependent on each other!
likened plant community to superorganism!
parts are functionally integrated —> matured the same way as an embryonic
organism!
-introducing the term: phytosociology!
tree, shrubs, herbs all have their own particular role!
loved the idea of “succession”; saw it as the same thing as developmental stages of
an organism!
plants will eventually reach stable “climax” stage from unstable “seral” stages!
thought that plant communities can be separated into discrete community types!
-typological thinking: “beech-maple forest” was a category!
explanation for ecological patchiness!
-true vegetation types would be separated by a special type of narrow transition
zone (he called it an ecotone)!
proposal is called organismal, holistic, community-unit, or closed-community
hypothesis!
-Henry Gleason (1926)!
differ from Clement’s idea!
provided explanation that didn’t depend on functional interdependencies!
simple idea emphasizing ranges of tolerance!
closely associated species can be found together as they have similar ranges of
tolerance to abiotic factor!
ecological/ sociological “roles” had no influence!
suggested that plant species should be found in wherever there’s suitable soil and
weather!
communities are open to any species that can grow in the local climate and soils!
claimed that ecotonal areas of rapid turnover are impossible to recognize!
2
You're Reading a Preview

Unlock to view full version