Download plants - Roslyn School

Principles of Ecology
Topic 24
I. Ecological organization


A. Ecology - the study of the
interactions of plants and animals
and their interrelationships with
the physical environment
B. Populations - all the members of
a species living in a given area

species - group of organisms capable
of interbreeding among themselves


C. Communities - all the plant and
animal populations of a given area
D. Ecosystems - a self-contained,
interdependent system of living
and nonliving things - must have 2
things


1. Constant source of energy
2. Continuous recycling of materials

E. Biosphere - portion of the earth
in which life exists - includes
water, land, and air (hydrosphere,
lithosphere, and atmosphere)
II. Characteristics of
Ecosystems

A. Abiotic factors - non-living factors often known as the limiting factors
because they limit the plant/animals
that can be found in the ecosystem




1. Moisture
2. Temperature
3. Nutrients in soil
4. Gases


B. Biotic factors - living part of the
ecosystem
C. Nutritional Relationships


1. Autotrophic nutrition - make their own
food
2. Heterotrophic nutrition - get their own
food from the environment

a. saprophytes - use dead organic matter as a
source of food - they are decomposers - break
down the organic remains of organisms - include
bacteria of decay (molds, fungi)





b. herbivores - eat plants
c. carnivores - eat other animals
(1) predators - kill and eat other living
things
(2) scavengers - eat dead organisms that
they have not killed themselves
d. omnivores - eat both animals and
plants

3. Symbiotic relationships - a
relationship in which two organisms
live together in a close nutritional
relationship



a. commensalism-one organism benefits,
the other is neither harmed nor benefits
b. mutualism-both organisms benefit
c. parasitism- one benefits and the other
is harmed
Examples of symbiosis

A. commensalism – one benefits and
the other is not hurt or harmed


(1) remora (shark sucker) and shark
(2) barnacle and whale

B. Mutualism – both benefit





(1)
(2)
(3)
(4)
(5)
bird and rhinoceros
lichens – fungus and algae
nitrogen-fixing bacteria and legumes
protozoa and termites
intestinal bacteria and humans

C. Parasitism – one hurt and the other
benefits







(1)
(2)
(3)
(4)
(5)
(6)
(7)
leeches
ticks
sea lampreys
mistletoe
ectoparasites – cling to exterior surface
endoparasites – live within the host
tapeworm - human

D. Energy flow



1. Food chain - starts with a green
plant or other autotroph that converts
sunlight to food - this energy is then
passed on to a series of animals
example:
grass --> grasshopper --> frog -->
hawk

2. Food webs - all the food chains in a
community - most organisms eat
more than one type of organism



a. producers - autotrophs - make own
food
b. consumers - feed on other organisms two types - primary eat plants directly,
secondary eat organisms that fed on
plants
c. decomposers - break down organic
wastes and remains of other organisms


3. Pyramid of energy - as energy is
transferred from producer to
consumer, much of the energy is lost
therefore there is more energy at the
producer level
4. Pyramid of biomass - the amount of
living material at each level - there is
more biomass at the producer level

E. Material Cycles

1. Carbon-hydrogen-oxygen cycle these are cycled by the process of
respiration and photosynthesis

2. Water cycle - evaporation,
condensation, and precipitation

3. Nitrogen cycle




a. nitrogen-fixing bacteria - convert free
nitrogen into nitrates - the nitrates are
absorbed by plants (legumes)
b. decomposers - bacteria of decay convert nitrogenous wastes into
ammonia
c. nitrifying bacteria - convert ammonia
into nitrates
d. denitrifying bacteria - break down
nitrogen compounds into free nitrogen
which returns to the atmosphere
III. Ecosystem
Development

A. Succession - the replacement of one
type of community by another



1. Pioneer organisms - first plants to
populate an area (lichens)
2. Changes in the environment - pioneer
organisms change the environment so other
organisms can survive
3. Plant successions - pioneer organisms -->
grasses --> shrubs --> conifers -->
deciduous trees



4. Animal successions - plants (flora)
are the source of food for the animals
(fauna) therefore the animals will
change with the plants
5. Types of communities - determined
by dominant plant species
6. Climax communities - when a
community becomes stable and does
not change unless a catastrophe
occurs

B. Types of ecological succession


1. primary - no soil present – must be
formed first
2. secondary – soil is already present –
occurs after something such as a forest fire
or hurricane – faster than primary


B. Competition - conflict between
organisms for natural resources
C. Niches - the role or job of a
species in its ecosystem – no two
organisms can occupy the same
niche
IV. Biomes

A. Biomes - the kind of climax
ecosystem that develops in a large
climatic area - may be terrestrial (land)
or aquatic (water)

1. Terrestrial Biomes - climate zones are
determined by latitude, altitude, large
bodies of water, mountains, and deserts - all
modify the climate of the nearby regions

climate includes the temp. range and amounts of
precipitation and solar radiation received

a. Kinds of Terrestrial Biomes

1. Tundra - permanently frozen subsoil
(permafrost)
 plants - lichens, mosses, grasses
 animals - caribou, snowy owl

2. Taiga - long severe winters, summers with
thawing subsoil
 plants - conifers
 animals - moose, black bear

3. Temperate Deciduous Forest - Moderate
precipitation, cold winters, warm summers
 plants - deciduous trees (maple, oak,
beech)
 animals - gray squirrel, fox, deer

4. Tropical forest - heavy rainfall, constant
warmth
 plants - many species of broad-leaved
plants
 animals - snake, monkey, leopard

5. Grassland - considerable variability in
rainfall and temperature, strong prevailing
winds
 plants - grasses
 animals - pronghorn antelope, prairie dog,
bison

6. Desert - sparse rainfall, extreme daily
temperature fluctuations
 plants - drought resistant shrubs and
succulent plants
 animals - kangaroo rat, lizard

b. Effects of latitude and altitude - with
increasing distance from the equator,
temp and rainfall show more variation
during the year

increasing altitude has the same effect on
climate as increasing latitude

B. Aquatic Biomes - make up the largest
ecosystem on the earth - more than 70% of
the earth’s surface is covered by water - the
majority of living things on earth are waterdwellers


more stable than terrestrial biomes - show less
variation in temp because water has a great
capacity to absorb and hold heat
organisms are affected by dissolved oxygen,
carbon dioxide, temp, light, kinds and amounts of
minerals and particles



Most photosynthesis takes place near the
surface since the light intensity is higher
there
Aquatic organisms are well adapted for
the removal of dissolve oxygen from
water.
They also have adaptations for
maintenance of proper water balance in
their cells which is affected by the salt
concentration

1. Different types of Aquatic biomes

a. marine biome - salt water biome - includes all
the oceans





most stable environment on earth
absorbs and holds large quantities of solar heat,
thereby stabilizing the earth’s temperature
contains a relatively constant supply of nutrients
and dissolved salts
it serves as a habitat for a large number and wide
variety of organisms
much of the photosynthesis on earth occurs along
the edges of the land masses (coastal waters)

b. Freshwater Biomes - includes ponds,
lakes, and rivers - vary widely in size,
temp, oxygen content, carbon dioxide
content, amounts of particles, current
velocity, and rate of succession

ponds and lakes tend to fill in over time - dead
plant material accumulates on the bottom and
around the banks and makes the water
shallower - goes from freshwater to a
terrestrial climax community
V. Patterns of Population
Growth


A. population growth is affected by birth rate,
death rate, and immigration and emigration
B. J-curve or exponential growth – every
generation increases in population size in an
exponential manner – happens when there is
a favorable new environment – cannot be
maintained because of environmental
limitations (diseases, resources, wastes, lack
of space)

C. S-curve – growth is exponential at
first and then slows and levels off at the
carrying capacity

D. population dispersal patterns – spatial distribution
of organisms
 1. clumped (contagious) - most frequent type of
distribution - indicating the existence of
aggregations or groups in the population – flocks
and herds of animals
 2. random (haphazard) - implies that the
individuals have been distributed by chance – free
floating marine larvae
 3. uniform - regularity of distance between and
among the individuals of a population – trees in a
forest
VI. Reproductive Strategies and
Population growth


A. sexual reproduction – occurs in most
complex multicellular organisms – helps
create and maintain diversity in the gene pool
of a population
B. asexual reproduction – allow a population
to grow very rapidly



(1) benefit – reduced cost to produce organisms
(2) cost – reduction of genetic variability
(3) parthenogenesis – when females reproduce on
their own – unfertilized egg becomes a new
female – ex. bees


C. Both asexual and sexual – asexual in the
times of abundant resources and sexual when
resources are limited
D. Two different strategies that affect the
number of offspring produced
 (1) r strategist - large number of young
produced but not taken care of
 (2) k strategist - small number of young
produced but taken care of (have a difficult
time recovering from catastrophic decrease
in population size

E. survivorship curves



1. Type I – have a high survival rate early
on in life and at middle age but death rates
increase as age increases – humans
2. Type II – constant mortality rates –
squirrels and birds
3. Type III – have a low survival rate early
on in life, but once they survive they are
able to live for a long period of time –
produce lots of offspring at once - mollusks
VII. Role of abiotic environment
in population growth


A. water – must regulate their water
content and salt concentration inside
and outside their cells
B. sunlight


(1) photic – water – area of the water that
light penetrates
(2) aphotic – no light – only heterotrophs
and chemoautotrophic organisms


C. oxygen supply – aquatic – utilize oxygen
dissolved in the water – pollution lowers
oxygen content and threatens aquatic life
D. Substratum (soil or rock)




(1) acidity (pH) – acid rain makes the soil pH too
low for most plants
(2) texture of soil and clay content – determine
the amount of water the soil can hold
(3) minerals – nitrates, phosphates, and other
minerals determine the type of vegetation
(4) humus quality – amount of decaying material
VIII. Competion and the niche


A. interspecific competion – between
species – when two populations overlap
in their niches – the more the niches
overlap, the greater the competition
B. Intraspecific competiton – between
organisms of the same species
IX. Marine Biomes


A. intertidal zone – region exposed at
low tide that undergoes variations in
temp and dryness – algae, sponges,
clams, snails, sea urchins, sea stars,
crabs
B. littoral zone – region on the
continental shelf that contains the
ocean area up to 600 feet deep – algae,
crabs, crustacean, fish


C. Pelagic Zone – typical of the open
ocean – contain photic and aphotic
zones – plankton, fish, sharks, whales,
diatoms
D. benthic zone – bottom regions of the
ocean
X. Humans and the Environment

A. Humans alter the environment
Increasing population puts strain on the
environment
B. Depleting Resources

1. Finite sources – there is only a set amount of the
resources – once they are gone, they are gone – these
are called nonrenewable – such as coal, oil and natural
gas
2. Replaceable sources – these sources can be renewed
over time – these are called renewable – such as corn,
trees, water

C. Pollution – anything added to the
environment that can cause damage to any
living thing


1. acid precipitation – burning fossil fuels
releases sulfur oxides and nitrogen oxides that
combine with water and form sulfuric acid and
nitric acid – this washes nutrients out of the
soil and affects aquatic organisms
2. Ozone Depletion - CFCs – destroy the ozone
layer which helps to protect us from UV rays
which cause cancer
3. greenhouse effect – burning of fossil fuels
releases carbon dioxide which holds in heat and
causes the temp. to rise - other greenhouse
gases include methane and water
4. water pollution – can kill aquatic life or cause
mutations – can also enter the food chain and
increase in magnification – this is called
biological magnification - can include lead,
DDT, mercury, PCBs
5. Thermal pollution – water is used to cool
industrial equipment – the hot dirty water is
put directly back into the environment where it
kills aquatic life




6. nuclear fuel – an energy source that does not pollute the
air or water with toxic chemicals but they can cause thermal
pollution and the radioactive wastes produced are a huge
environmental problem
7. water usage – increased industrialization increases the
use of water
8. smog – kind of air pollution that occurs when air
pollutants react with sunlight
9. eutrophication – when fertilizer runoff goes into lakes and
increases the amount of phosphorus the algae increases –
as the algae dies bacteria increase which decreases the
amount of dissolved oxygen causing the fish to die off which
leads to death of the whole lake
XI. Conservation of resources

A. Using resources wisely
1. reduce – reduce our use of resources – for
example turning off lights when not in use
2. Reuse – using an item over and over
again or using it for purposes other than its
original use – for example using your own
cloth bag at the grocery store instead of
using plastic
3. Recycle – take aluminum cans to be
recycled into another material



B. Renewable Resources – solar power, wind power,
hydroelectric, geothermal and methane gas
C. Reducing Pollution
 1. water treatment plant
 2. smoke stacks with scrubbers to remove particulates
and sulfur dioxide
 3. biological control of insects – hormones
(pheromones), natural predators
D. Protecting Biodiversity
 1. endangered species – help protect habitat,
reintroduction programs, and breeding programs