Ecological Succession and Community Dynamics - Ecological Systems - page 38

that was exposed with variation in Lake Michigan. The oldest of the dunes, which is
the furthest away from the Lake Michigan beach, has a loamy brown forest soil and
is covered by a Beech-Maple ( Fagus-Acer ) forest; the youngest dune at the beach
front has windblown sand as a soil and is covered with a patchy beach-grassland.
Cowles recognized this entire land pattern represented a chronosequence, with the
spatial location of the dunes of different ages representing different stages of
successional development. He later [ 29 ] produced the now famous phrase that
“succession was a variable chasing a variable” - the changes in vegetation chase
the changes in the climate. This insight was, and remains, a remarkable concept of
vegetation function. What he meant by this was that the rate of change of vegetation
succession, the variable, is sufficiently slow that one could expect the climate, the
chased variable, to change by the time the succession process was completed.
Cowles was a remarkable and innovative scientist. He was honored in the 1935
issue of Ecology , the journal of the Ecological Society of America. The Henry
Chandler Cowles issue ( Ecology , Volume16, Number 3) is a collage of the central
issues in plant ecology in its formative years: C.C. Adams, [ 30 ] an early researcher of
ecological succession and the associated bird communities, along with F.E.
Clements, [ 31 ] wrote on human ecology and ecology in the public service; Transeau
[ 32 ] discussed the “Prairie Peninsula,” a region of prairie vegetation jutting into
a forests in the American Midwest, and emphasized that one must consider past
climates as well as present climates to understand vegetation; Fuller [ 33 ]andSears
[ 34 ] made much the same point looking at paleoecological data; several students and
colleagues of Cowles presented data on mature vegetation in different areas.

A.G. Tansley and the Ecosystem Concept

The first of the papers in the Cowles issue and different in tone from the rest, was
Tansley's now classic 1935 paper on “The use and abuse of vegetational concepts
andterms.”Tansley[ 5 ] discussed the ideas of the American, F.E. Clements, and
the amplification of these ideas by the South African, John Phillips. Tansley
declared his strong disagreement with three of Phillips' papers in the Journal of
Ecology [ 14 - 16 ] characterizing ecological communities as “quasi-organisms”
whose successional dynamics were analogous to embryological development,
“The community is born, grows, matures, reproduces, and carries out various
other biotic phenomena: it behaves in a manner similar to an individual, with
obvious and natural differences inherent in its wholly divergent and far more
complex structure, constitution and functions. It behaves in such a way as to justify
the view that not only is it similar to an organism, but that it is a kind of organism
...

” This conceptualization is in keeping with the principle of holism from
Aristotle's Metaphysica onward and often abbreviated as “the whole is greater
than the sum of its parts.” Phillips attributed many of his ideas to Jan Smuts' topic,
Holism and Evolution [ 35 ] and noted later in writing a eulogy for Clements, [ 36 ]
that his colleague Smuts was profoundly influenced by the writings of Clements.