Geoscience Reference
In-Depth Information
energy to kinetic and, ultimately, potential energy. The
potential energy is subsequently converted to kinetic
energy as the rock particles tumble, sludge or wash down-
slope. Friction with the surface and between the particles
releases further energy in the form of heat.
the atmosphere, all three forms being converted to
chemical energy by the plant. As the vegetation dies, or
animals devour the plant material, this energy is cycled
through the environment. Animals convert the chemical
energy to heat for bodily warmth and to kinetic energy
for motion. They return some energy to the soil and the
atmosphere as chemical energy.
Similar processes operate in aquatic ecosystems,
although in their case much of the initial input of
chemical energy is derived from organic matter washed
into the waters from the land.
On a global scale it is impossible to quantify precisely
the effects of all these processes. What is clear is that
energy transfers create a fabric of relationships that bind
the global system together, and provide the motive power
for the processes that operate within our world, and which
are the very foundation of our existence.
Ecological transfers
On land the formation of soil, the growth of plants and
the support given by this vegetation to animals all reflect
further energy transfers and conversions.
In the case of terrestrial ecosystems (
Figure 2.19
)
the
development of soil cover involves weathering, which in
turn reflects the transfer of chemical energy from rocks
to soil. Plants take up substances from the soil and store
the chemical energy in their tissue. They also use radiant
energy from the sun, and chemical and heat energy from
Sun
Radiation
ATMOSPHERE
VEGETATION
ANIMALS
Radiant
energy
Respiration
and
Transpiration
Respiration
Movement
Photosynthesis
Grazing
BODY TISSUE
GREEN TISSUE
Heat
Plant
uptake
Plant
debris
Gas
release
Waste and
death
SOIL
Decomposition
NUTRIENTS
Chemical
Radiant
Heat
Kinetic
Weathering
ROCK
