207
See also: The distribution of species over space and time 162–163 ■ Climax
com mu n it y 172 –173 ■ Open community theory 174–175 ■ Biogeography 200–201to his idea of climax communities in- The same year, Clements used
the term “biome” to describe biotic
communities—all the interacting
organisms within a specific habitat.
Like-minded thinkers
Clements was not the only one
thinking along these lines. Zoologist
Victor Shelford was working toward
the same idea. The pair began to
meet over the next 20 years, while
pursuing their own research, to see
how they could combine the worlds
of plants and animals. Clements
studied plant biomes in Colorado
with his wife, the eminent botanist
Edith Clements. Meanwhile, Shelford
compiled the Naturalist’s Guide to
the Americas (1926)—the first major
geographical summary of wildlife in
the Americas, in which he talked
about “biota.” This book laid much
of the foundation for later findings.
Ways of looking at interactions
in ecological communities took a
major step forward when British ❯❯THE LIVING EARTH
The Mongolian steppe belongs to the
same grassland biome as the prairies
in North America. Despite being on
separate continents, they are linked
by their climate, animals, and plants.The major types of plants
in each region match
precipitation
and temperature
patterns closely.Different plants flourish
in each climatic region.The major plant
types can be used
to divide the world
into broad natural
zones called
biomes, which
reflect variations
in climate.The geographic spread
of plants is determined
mainly by climate.Threatened coral
reef biomesCoral reefs are such bountiful
habitats that they are often
seen as the tropical rain
forests of the sea. They
support a quarter of all marine
species and provide livelihoods
for half a billion people. Yet
they now face catastrophe.
Half of all reefs have been lost
in the last 30 years, and some
experts estimate that 90
percent will be gone over the
next 30 years. The main global
threats are ocean acidification
and global warming. As seas
warm, stressed corals expel
the algae they rely on for food.
They stop growing, lose their
colour, and often die in what is
called a coral bleaching event.
Such events are becoming
ever more frequent. There are
local threats, too, including
overfishing, both for the table
and for aquariums. Even more
seriously, to catch fish for
aquariums, sodium cyanide is
often squirted into the water
to temporarily immobilize the
fish, and this kills corals. More
brutally, fish for the table are
often caught by throwing
dynamite into the water. This
kills fish, making them easy to
scoop up in vast numbers, but
it also blasts coral reefs apart.US_206-209_Biomes.indd 207 12/11/18 6:25 PM