The journal Ecology
posthumously publishes
Raymond Lindeman’s article
“The trophic-dynamic
aspect of ecology.”1942
1935
Arthur G. Tansley coins the
term ecosystem, arguing
that an environment and all
its living organisms have
to be seen as a single,
interactive whole.W
hen Aristotle wrote
about plant and animal
species existing for the
sake of others, he showed a basic
understanding of food chains—
as have countless observers of the
natural world since ancient Greek
times. Arab scholar Al-Jahiz
described a three-level food chain
in the 9th century, as did the
Dutch microscopist Antonie van
Leeuwenhoek in 1717. British
naturalist Richard Bradley
published more detailed findings
on food chains in 1718, and in 1859,
Charles Darwin described a “web
of complex relations” in the natural
environment in his book On the
Origin of Species. The concept of a
food web, with many predator-prey
interactions, was then further
developed by Charles Elton in his
classic Animal Ecology (1927).The concept of the ecosystem (“a
recognizable self-contained entity”)
followed soon after, when in 1935,
British botanist Arthur Tansley
wrote that organisms and their
environment should be considered
one physical system. In his Ph.D.
thesis, American ecologist
Raymond Lindeman expanded
on Tansley’s work, positing that
ecosystems are composed of
physical, chemical, and biological
processes “active within a space–
time unit of any magnitude.”
Lindeman also conceived the
idea of feeding levels, or trophic
levels, each of which is dependent
on the preceding one for its survival.
In 1960, the American team of
Nelson Hairston, Frederick Smith,
and Lawrence Slobodkin published
findings on the factors controlling
animals on different trophic levels.They identified both the top-down
pressures exerted by predators and
the bottom-up pressures exerted by
limitations on food supply. Twenty
years later, American ecologist
Robert Paine wrote of the trophic
cascade effect—the way a system
is changed by the removal of a key
species. He described changes to
the food web after the experimental
removal of the ocher starfish from
an intertidal zone. This predatory
echinoderm was shown to be a
keystone species, playing a crucial
role within its ecosystem.Island isolation
Habitat fragmentation is now a
major problem in most terrestrial
environments because it leaves
specialist organisms isolated.
For that reason, research into the
biogeography of islands—those130 INTRODUCTION
Charles Darwin
describes food
webs in his On the
Origin of Species.1859
1927
Charles Elton
develops the idea of
the food web in Animal
Ecology and introduces
the concept of the
ecological niche.Nelson Hairston,
Frederick Smith, and
Lawrence Slobodkin’s
“green world hypothesis”
argues that the predator–
prey balance is key to
flourishing ecosystems.1960
1957
G. Evelyn Hutchinson
establishes the concept
of niche breadth at
the Cold Spring
Harbor Symposia on
Quantitative Biology.1718
Richard Bradley
describes how plants,
pollinating insects,
and insectivores rely
on one another in a
food chain.US_130-131_Ch_5_Ecosystems_Intro.indd 130 12/11/18 6:24 PM