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
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