170
I HAVE GREAT
FAITH IN A SEED
ECOLOGICAL SUCCESSION
T
he Indiana Dunes comprise
a windswept section of
shifting sand along the
southern shore of Lake Michigan,
US. In 1896, American botanist
Henry Chandler Cowles saw these
dunes for the first time, and so
began his career in the emerging
field of ecology. Dunes are among
some of the planet’s least stable
landforms, and therefore changes
to their ecology happen relatively
quickly. As Cowles walked among
the dunes, he noticed that when
certain plants died off, theirdecomposing matter created
favorable conditions for other plants.
As these new plants died, even more
plants could grow.
Based on his observations,
Cowles developed the idea of
ecological succession, although
groundwork for the concept had
been laid by earlier naturalists. In15,000 years ago, there would only
have been bare sand around Lake
Michigan’s shore. Vegetation developed
in a physical gradient, with sand nearest
the water and forests farthest back.IN CONTEXT
KEY FIGURE
Henry Chandler Cowles
(1869 –1939)BEFORE
1825 Adolphe Dureau de
la Malle coins the term
“succession” when describing
new growth in forest cuttings.1863 Austrian botanist
Anton Kerner publishes a
study of plant succession in
the Danube river basin.AFTER
1916 Frederic Clements
suggests that communities
settle into a climax, or stable
equilibrium, at the end of a
succession period.1977 Ecologists Joe Connell
and Ralph Slatyer argue that
succession occurs in diverse
ways, highlighting facilitation
(preparing the way for later
species), tolerance (of lower
resources), and inhibition
(resisting competitors).US_170-171_Ecological_succession.indd 170 12/11/18 6:25 PM