Community Ecology
G.1.1 Outline the factors that affect the distribution of
plant species, including temperature, water, light, soil pH,
salinity, and mineral nutrients
 High temperature denatures enzymes
and slows growth of plants; the rate of
transpiration is also increased.
 Low temperatures decrease enzyme
activity and freezing temperatures
inactivate enzymes.
 Water is needed for enzyme activity,
transport, photosynthesis, support, and
many other things. There is a low
diversity of plants in deserts and polar
regions.
 Light is important for
photosynthesis and flowering.
Because of this, dark areas have
small numbers of plants.
 Soil pH is important for absorption
of nutrients. If soil is acidic,
desertification can occur; the use
of limestone can neutralize the soil.
 Salinity has an affect on the absorption
through osmosis. High salinity causes
plants to lose water through osmosis.
Halophytes live in high salinity.
 Mineral nutrients are needed for many
important functions. Nitrogen is needed
to make proteins, enzymes, nucleotides,
vitamins, and other compounds.
Phosphorous is used in the formation of
phospholipids and other structures.
G.1.2 Explain the factors that affect the distribution of
animal species, including temperature, water, breeding
sites, food supply and territory
 Temperatures affect
the concentration of
animals. Only
especially adapted
organisms can live in
extreme
temperatures.
 Water is needed for
important functions,
so only animals that
can conserve water
are found in deserts,
like snakes.
 Breeding sites are needed for
growth and protection of young.
High animal diversity is found in
areas with varied topographical
nature.
 Food supply is important for
survival since animals are
heterotrophs. High animal diversity
is once again found in the rain
forest.
Some animals are territorial and need
large areas for feeding, mating, and
protecting their young. Some are territorial
during breeding season and occupy areas
to prevents others from approaching them.
There is high animal distribution where
there is room to occupy territory and
defend against other members of the
species.
G.1.3 Describe one method of random sampling, based on
quadrate methods, that is used to compare the population size
of two plants or two animal species
 Create a plot and make a grid on a map.
 Number the grids and measure
population size in those quadrates
 Calculate average population density and
multiply to get total population
G.1.4 Outline the use of a transect to correlate the
distribution of plant or animal species with an a biotic
variable
 Stretch a rope down the area that you want
to investigate. At predetermined intervals,
measure the population size for the
organism you are interested in. These
measurements can be at the point on the
rope or (point transect), in a belt transect,
in a band going on both sides of the rope.
You may see changes in the species present
as abiotic factors change along the length of
your transect.
 You use a transect to correlate the
distribution of a plant or animal species with
an abiotic variable
G.1.5 Explain what is meant by the niche concept, including an
organism’s spatial habitat, its feeding activities and its
interactions with other species
 A niche is all the
characteristics, biotic
and abiotic, specific to
a species. It includes
the habitat, nutrition,
and relationships. For
example, the place
that the species
sleeps, lives, breeds,
its food source and
relationship with other
species.
G.1.6 Outline the following interactions between species, giving
two examples of each: competition, herbivore, predation,
parasitism, and mutualism
 Competition is when
two species need the
same resource such
as a breeding site or
food. Usually one of
the species will outcompete the other.
The European
starlings and
American Robins are
birds that compete in
part of their niches.
 Herbivory is the relation between
an animal and a plant. Different
animals feed on different plants.
Deer feed on tree leaves, rabbit
feed on grass, giraffes on trees.
 Predation is the relation between
the predator, which is usually
bigger, and the prey, which is
usually smaller. An example would
be a fox and a rabbit, or bonitos on
anchovies.
 Parasitism is the relation between the
host and the parasite. The parasite
causes harm to the host to get food and
other resources. Examples of parasites
are the malaria protist and tapeworm in
humans.
 Mutualism is where two members of
different species benefit and neither
suffers.
G.1.7 Explain the principle of
competitive exclusion
 No two species
can live in the
same niche,
because there
is competition
for the
resources of
the land and
only one
species will
survive.
G.1.8 Distinguish between
fundamental and realized niches
 The fundamental
niche is the potential
mode of existence,
given the
adaptations of the
species.
 The realized niche is
the actual mode of
existence, which
results from its
adaptations and
competition with
other species
G.1.9 Define biomass
 The total organic
matter comprising
a group of
organisms in a
particular habitat
 The weight of all
the organisms in
the same trophic
level
G.1.10 Describe one method for the measurement of
biomass of different trophic levels in an ecosystem
 Biomass: Measure total
area of ecosystem.
 Divide ecosystem into
small areas (grid/plot).
 Sample from one/few
grids/plots.
 Measure and remove all
plant materials from
that
 Dry
 Create a calculation to
convert your estimate
of total wet weight to
total dry weight