Introduction
- The chickaree lives in the forests of the Sierra Nevada and eats pine
cones .
- Animals depend on the plants of the forest for
oxygen
as well as for food.
- Some plant seeds are dispersed by clinging to the
coats
of animals, or in the
digestive
tracts of animals.
- The pattern of interactions among organisms and their environment is called a(n)
ecosystem .
- The living or biotic part of an ecosystem is called a(n)
community .
- Through
photosynthesis ,
trees and other plants convert the energy of sunlight into the energy of
chemical
bonds.
- The green plants are thus the
producers
of the ecosystem.
- In contrast to the plant producers, the deer and mountain lion are
consumers .
- Organisms which break down and recycle materials in wastes and dead bodies are called
decomposers .
- Producers are often called
autotrophs
- they make their own food; consumers and decomposers are called
heterotrophs
- they get their food from other organisms.
Section I: Trophic Structure
- A butterfly is an example of a
primary
consumer in the trophic pyramid.
- The hawk is a
tertiary
consumer if it eats an insect-catching bird.
-
Primary
consumers are also called herbivores.
- In a forest ecosystem, the insects outnumber the trees, so the pyramid of
numbers
is partially inverted.
- The pyramid of
biomass
may sometimes seem inverted if producers have a higher reproductive rate than consumers.
- The pyramid of
energy flow
is always upright, since the number of calories always
decreases
as one goes up each level.
Section II: Energy Flow
- Energy enters most ecosystems in the form of
solar
radiation, and leaves as
heat .
- Because energy passes through the ecosystem and is not reused, the ecosystem is said to be a(n)
open
system with regard to energy.
- A mouse is about
10
% efficient at turning cheese into cat food.
- Most food chains contain
five
or fewer links.
- Plants convert about
1
% of solar energy into food for grasshoppers and mice.
- Energy
export
occurs when energy leaves an ecosystem, while energy
import
occurs when energy is introduced into an ecosystem.
- Our
fossil
fuel reserves are composed of stored production energy from ecosystems of the past.
Section III: Materials
- In photosynthesis,
carbon dioxide
and
water
are combined to form glucose.
- The compounds from photosynthesis are broken down by respiration, where energy is release, and
carbon dioxide
and
water
are re-formed.
- With regard to materials, the ecosystem is a
closed
system.
- Carbon moves from the
atmospheric
pool to the
biotic
pool in photosynthesis, and is transferred from the biotic pool back to the
atmospheric
pool when CO2 is released as a product of respiration.
- The carbon trapped in ancient sediments makes up the
sedimentary
pool, which cycles slowly under natural conditions.
- Tropic forests undergo
rapid
recycling of materials, while fir forests undergo
slow
recycling.
- Carbon dioxide in the atmosphere traps solar energy, keeping the earth warm - the so-called
greenhouse
effect.
- Copper and cobalt are needed in only tiny amounts as
cofactors
of certain enzymes.
- Only a few kinds of microorganisms can use N2 gas directly, through the process of biological nitrogen
fixation .
- In an ecosystem, energy movement is always
one
-way, while materials are always
reused ,
recycled over and over.