Ecology Deals with interactions
among organisms
Interactions between
organisms and the
environment
Dependent on
Biotic factors -Effect of living
organisms in the environment,
both direct and indirect
Abiotic factors – effect of non
living – water,oxygen, light,
temperature, soil, organic and
inorganic nutrients
Light
Energy for all living things
comes directly or indirectly
from the sun
Aquatic environments –
light is absorbed as it
passes through water
 Photic layer of water
which has light
 Aphotic layer – no light
Water+oxygen ,in the presence of
sunlight = producers make glucose
Temperature
Vary with latitude and
altitude (vertical
distance above sea
level)
Nearby geographic
features
Soil and minerals
Soil –mostly smaller rock
particles broken down from
larger by water and wind
weathering
Minerals in the soil
dependent on the kind of
rock from which it has been
weathered
Soil – Topsoil
Uppermost layer
organic matter(humus)
and living organisms,
plant roots,
earthworms,insects
Humus – from decay of
dead plants and animals
Organisms of decay –
fungi and bacteria
Next layer –
subsoil
Rock particles
mixed with
inorganic
compounds
Including
minerals
Bottom layer
Bits of rock
broken off
from the
bedrock
below
Types of soil
Sandy – largest particles
water drains too quickly
Clay – small particles –
water drains too slowly
Silt – intermediate size
Biosphere – portion of the earth
where living things exist divided into
1.Lithosphere – solid part of
earths surface
2.Hydrosphere –water
3.Atmosphere – mass of air
surrounding the earth
Population- all individuals of a
particular species in a certain
area
Community – all the
populations of different
organisms in a particular area
Ecosystem – community + it’s
physical environment
Ecosystems contain….
Autotrophs– make their own food using
carbon dioxide,water and the suns
energy – plants - Producers
Heterotrophs : consumers
Herbivores(plant eating); carnivores
(meat eating);
Omnivores(both plant and animal
eaters)
Predators(attack and kill prey) ;
scavengers – (feed on dead animals) ;
Saprobes(break down remains of dead
organisms)decomposers – bacteria,fungus
Symbiotic relationships
Two
different
organisms
live in close
association
Mutualism –
both
organisms
benefit
Commensalism –one
organism benefits and the
other is not affected
Parasitism
One organism
benefits and
the other is
harmed
Habitat- each organism has a
particular place where it lives
Niche – particular role in an
ecosystem
Food chains and food webs –
feeding relationships
Energy stored in
organic nutrients
transferred to
consumers
Herbivores – first
order consumers
Carnivores –
second order
consumers
Food webs -
Pyramid of energy and biomass
Amount of energy available at
each level decreases with each
higher feeding level
Usually 10% of energy
(biomass) transferred at each
level
Energy transfer
Only 10%
transferred at
each level
Biogeochemical cycles
Materials recycle between
living things and the
environment
Nitrogen,carbon,oxygen,water
Nitrogen cycle
Basic component of proteins
and nucleic acids
Even though nitrogen is
about 80% of the
atmosphere plants cannot
use it directly
Nitrogen fixation –
specialized bacteria in
legumes convert nitrogen to
nitrates which plants can use
Nitrogen cycle
Carbon and Oxygen cycle
Carbon - .03% of
atmosphere, dissolved
waters of the ocean,
converted by plants into
organic compounds
during photosynthesis
Oxygen – 20% of
atmosphere – released
into atmosphere during
photosynthesis and
removed by cellular
respiration
Carbon
–
Oxygen
cycle
Water cycle
Cycling of water between the surface
of the earth and the atmosphere
Ecological succession
Process by which an existing
community is slowly replaced by
another one.The species that has
the greatest effect on the
community is called the Dominant
species.
Succession continues until a climax
community is reached.
Primary succession – is in an area
that has no existing life – rocky
cliffs, newly formed volcanic islands
Secondary succession – area in which
an existing community has been
destroyed – farmed land which has
been abandoned
Succession in lakes and ponds Sediment,fallen leaves accumulate in the
bottom > moss and reeds grow on the
banks >lake gets filled in and become
marsh > dry land
Human ecology - Chapter 39
relationship between humans
and the environment
Human population
growth
year 2000 - 6 billion
Limiting factor - limits further
growth - lack of food
Carrying capacity - size of a
population that can be
supported by an environment
Population remains the same if
the birth and the death rates are
equal and there is no change
from migration
Developed - death rate low
- good medical care
Developing - birth rate high
- population growth
Urbanization
population moves to cities destruction of farmlands to
make housing
over farming and overgrazing fields without vegetation - soil
removed by wind and water
causing erosion
Pollution
adding anything to the
environment that makes it
less fit for living things
noise pollution
pesticides - contaminates
air,water,disrupts food
chains - DDT
continued……
air pollution - sulfur dioxide(burning
of coal) mixes with rain water to
produce ACID RAIN ; carbon
monoxide and nitrogen oxides( car
exhaust ,industry)
water pollution - eutrophication explosive growth of algae,uses up all
the dissolved oxygen and the fish die
Land pollution - sanitary landfill,
burning refuse in incinerators
Restoring the environment
controlling pollution - car
emissions and unleaded
gasoline
sewage treatment breakdown sewage before
it goes back to waterway
recycling and reusing to
avoid filling land fills
Conserving Natural Resources
Renewable -air,water,soil,sunlight,
nonrenewable - coal,oil,natural
gas,metals,minerals
biological pest control pheromones
conserving wildlife- legal
protection of endangered species
conserving forests - reforestation
Conserving soil
Strip cropping - cover crops
planted between strips of
regular crops
Terracing - sides of hills
Contour farming - rows on
slopes
windbreaks - prevent wind
erosion