Biology Now, 2e

338 ■ CHAPTER 18 General Principles of Ecology

ECOLOGY

is preventing the growth of new trees. If any

strategies work well on the small plots, perhaps

they can be adapted to save larger areas of rain-

forest affected by fire.

“We’re hoping we find ways to help the

forest recover,” says Balch. Still, the research-

ers worry about the future of the region. “Have

we crossed a threshold where this part of

the forest isn’t going to grow back as rainfor-

est?” asks Coe, worry in his voice. If that is

true for the small experimental plots, it bodes

danger for large regions of the Amazon that

border agricultural land and are threatened

by wildfires.

● (^) Ecology is the study of interactions between
organisms and their environment. All ecological
interactions occur in the biosphere, which consists
of all living organisms on Earth (biotic factors),
together with the physical environment they inhabit
(abiotic factors).
● (^) Weather consists of the short-term atmospheric
conditions in a given area, such as temperature,
precipitation, wind, humidity, and cloud cover.
Climate, the prevailing weather of a specific region
over relatively long periods of time, has a major
effect on the biosphere. Climate is determined by
incoming solar radiation, global movements of air and
water, and major features of Earth’s surface.
● (^) Climate change is a large-scale and long-term
alteration in Earth’s climate, and it includes such
phenomena as more extreme temperatures, change
in rainfall patterns, and increased frequency of
violent storms.
● (^) Carbon dioxide acts as a greenhouse gas and
contributes to the greenhouse effect by absorbing

REVIEWING THE SCIENCE

heat released at Earth’s surface, rather than allowing

it to leave the atmosphere. The greenhouse effect

has led to a rapidly rising average global temperature,

a phenomenon known as global warming.

● (^) The concentration of carbon dioxide (CO 2 ) gas in the
atmosphere is increasing at a dramatic rate because
of an increase in carbon sources, such as the release
of CO 2 through the burning of fossil fuels, and a loss of
carbon sinks, such as the absorption of CO 2 through
photosynthesis in large forests.
● (^) Both the hydrologic cycle and the carbon cycle are
affected by global warming, which disrupts the
natural cycling of water and carbon molecules in
the biosphere.
● (^) The area of the biosphere required to produce the
resources and to absorb the waste produced by an
individual or population is known as the ecological
footprint. The ecological footprint is often expressed
in Earth equivalents, the number of planet Earths
needed to provide the resources and absorb the
waste of an individual or population.

THE QUESTIONS

The Basics

(^1) The biosphere is
(a) all organisms on Earth, together with their
physical environments.
(b) crucial to human survival and well-being.
(c) a source of food and raw materials for human
society.
(d) a web of interconnected ecosystems.
(e) all of the above
(^2) Greenhouse gases function by
(a) blocking sunlight but letting out heat from Earth
to outer space.
(b) absorbing heat that radiates from Earth that
would otherwise escape to outer space.
(c) absorbing heat that radiates from the sun toward
Earth.
(d) releasing heat that radiates from Earth into outer
space.