A Local Ecosystem

Key Terms

Abundance

Ecosystems

Diversity

Biotic

Distribution

Environments

Abiotic

The area or range of locations in which a species can be found

Variety, range of different things

How many individuals are present

Any area that contains living organisms interacting with each other and their environment

Relating to the biological parts of an environment

Relating to the physical parts of an environment

Factors:
Plants, animals, microbes (bacteria, fungi)

Factors:
Available light, available water, rainfall, temperature, wind direction and strength, soil and water pH, dissolved ions, gases (Oxygen, Carbon dioxide), Viscosity, buoyancy, pressure, salinity

Terrestrial:
environments an these found on land
e.g. desert, rainforest ecosystem

Aquatic:
(water) environments are these found in salty water or marine environments (e.g. coral reefs) and freshwater environments (e.g. lakes)

Abundance and Distribution

Biotic factors may determine distribution and abundance of species:
availability and abundance of foods
number of competitors
number of mates
number of predators
number and variety of disease-causing organisms

Abundance of species not a random occurrence

Sampling Techniques #

Used to make population estimates when total counts cannot be made

No. of organisms in population always changing
Ecosystems usually remain in dynamic equilibrium #

Equilibrium: a state which opposing forces or influences are balanced

Transects

Measuring Abundance and Distribution # #

Direct counting, selecting a sample area or many using this as guide/use quadrat method, doing estimate % cover,

Do profile sketch, do transect, make surface map sketch, plan sketch, make direct observations, use radar cameras or tagging/ marking to observe animal movements

Quadrats

Capture - Recapture

large areas to measure distribution usually plants gives idea of variation that may occur in that area

narrow strip that crosses entire area being studied, from one side to the other

Advantages
useful when are is too large
Disadvantages:
only record organisms along transect line, may not be accurate representation of the area

good for studying changing distribution of plants
abiotic factors change go does vegetation

Environment -physical and chemical --> abiotic factors
Biotic Factors - plants and animals --> species (breeding) --> communities (groups)

Energy: capacity for doing work, contained in bonds between atoms/molecules in food, cannot be created destroyed

Measure abundance of plants by plans fixed area squares randomly in an area

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used to count animals that more around

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Advantages
since divided by random quadrats, easier to find abundance of species
Disadvantages
only for plants/slow-moving species

Advantages
gives estimate of abundance for animals in large populations that are difficult to count
Disadvantages
only suitable for mobile animals, time consuming, disturbing environment

Population Trends #

population of an organisms are rarely the same from year to year and can be affected by:

availability of food/water - up/down
predation - down
reproduction - up
disease - down
competition - down
human activity - up/down

Relationships in Ecosystems

Allopathy

Parasitism

Mutualism

Commensalism

an organism secretes or excretes substance that has inhibitory effect on another organism
e.g. walnut, lantana

between number of different species, parasite lives on/in a host and feeds from it
e.g. tapeworms and cows/ pigs/humans, ticks and dogs

members of different species, both benefits
e.g. insect and plant - bee (nectar), flower(pollinated)

different species, one benefit the other unaffected
e.g. bird nesting in tree

Food Chain

energy food chain begins both g producer organism

Energy flows in direction shown by arrows
some energy is lost in food chain
source comes from the Sun

maize -> locust -> lizard -> snake
producer -> primary consumer -> secondary -> tertiary

Food Web

feeding relationships of living things are much more complicated

branching diagram showing feeding relationships (and energy flow) of all living things in an ecosystem

Trophic Interactions

Insectivore

Scavenger

Omnivore

Decomposer

Carnivore

Autotroph

Herbivore

Heterotroph

Consumer of plant material

Consumer of animals

Consumer of plants or animals

consumer of insects

Feeds on dead or decaying material

Absorbs nutrients from dead material and waste

Makes its own food

Feeds on another living thing, consumer

returns organic material to soil

bacteria and fungi

Pyramids of Biomass #

measure of mass of all organisms of a particular trophic level
shoes total weight(biomass) of organisms at each level for particular habitat

Pyramids of Number

if no. of organisms at each trophic level is considered, this produces food pyramid

Respiration

Photosynthesis #

Competition #

occurs because different orgasms need to acquire a limited factor in environment

organisms compete with members of own species or another

Intraspecific:
between members of same species #

Interspecific:
between members of different species

usually interspecific competition less intense

likely due to member of same species having far more common resource needs

Plants

less noticeable

competes for:
light, water, minerals, space

some are better able to compete

Animals

competes for:
food, water, mates, land (territory)

possess various defence mechanisms

attacking intruders with teeth, claws, stingers, chemical means
camouflage to hide

Effects

affect population numbers due to impact on reproduction and survived rates
population fluctuations directly linked to competing species and their resources

if resolver is common food source:
-food Sources become more readily available, abundance of both species increases
-food sources decrease so may abundance of competitive species

short term

decrease in population numbers

long term

if trend of one species out-compete continues, long periods of decrease reproduction rates and death will eventually lead to elimination of 'losing' species in the area
longer scale is possible extinction

Human Impacts

Land Clearance

Slash and Burn Agriculture

Integrated and Water Degradation

Erosion

cleaning of large areas of ecosystem

cleaning with burning

poor waste management, dams, irrigation runoff, roads, mining

livestock, cleaning ploughing, roads, housing development

On a larger scale

Soil and Water Salinity

Polluting the Atmosphere

Soil Acidification

Introduced Species

chemical runoff into soil water

irrigation runoff

industrial gases, vehicle emissions

fox, rabbit, cane to all, lantana

Biodiversity

variety of all forms of life, diversity of characteristics they contain, characteristic diversity within species allows populations to adapt to changing environment

Aerobic

requires oxygen

Anaerobic

does not require oxygen

green plans makes organic molecule (e.g glucose) from raw materials e.g. Carbon dioxide, water, light energy

Photosynthesis requires green pigment 'chlorophyll'.

found in cellular structures 'chloroplast'

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cell break down complex molecules to obtain energy. is stored in molecule called 'ATP'

occurs in cellular structure 'mitochondria'

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cells break down glucose molecules to release energy in mitochondria

glucose is combined with oxygen and carbon dioxide and water are produced

Adaptations

characteristic that increases chance of survival and reproduction for species

makes organisms more suited for life in their natural environment,

3 types of adaptations

Physiological

Behavioural

Structural

physical characteristics: parts of animals and plants

finches or processes that enable survival in ecosystem

the way on organism acts