Abiotic/Biotic factors - SandyBiology1-2

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Transcript Abiotic/Biotic factors - SandyBiology1-2

7: Environmental Factors & Their
Influence
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The Environment:
is our surroundings or external factors and
forces (conditions) that affect an organism or
a group of organisms
- Physical (air, water, soil)
- Biological (biosphere: plants; animals)
- Societal (our culture; political system)
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Earth’s Spheres
ATMOSPHERE Air
Contains all the air in Earth’s system.
BIOSPHERE Living Things
Contains all of Earth’s living things—
microorganisms, plants, and animals.
LITHOSPHERE Land
Contains all the cold, hard, solid
land of Earth’s crust (surface), the
semi-solid land underneath the crust,
and the liquid land near the center.
HYDROSPHERE Water
Contains all the solid, liquid, and
gaseous water of Earth.
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EVENT
Mt. Pinatubo
Eruption
Atmosphere
Biosphere
Lithosphere
Hydrosphere
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Ecology
• The study of interactions that take place
between organisms and their environment.
• It explains how living organisms affect each
other and the world they live in.
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Abiotic/Biotic factors
– In an ecosystem, there are various factors that
affect the survival and welfare of a population.
– These factors are classified as:
• abiotic
• biotic.
Abiotic/Biotic factors
– In an ecosystem, there are various factors that
affect the survival and welfare of a population.
– These factors are classified as:
• abiotic
• biotic.
Abiotic factors : involve all those factors that
are non-living.
• For example– Soil pH
– Soil Humidity
– Soil Temperature
– Air Temperature
– Wind Speed
– Sunlight Intensity
– Soil Nutrients
Biotic factors : involve all those factors that
are living.
• For example– Competitors
– Predators
– Decomposers
– Population Density
– Disease
Limiting Factors
• Some abiotic and biotic factors affect the
organisms sufficiently to limit population
growth.
• These are known as limiting factors.
• The factor may be too little in quantity or too
much.
• For example, the limiting factor for a plant population near
a chemical factory may be the soil pH.
Liebigs Law of the Minimum
• The success of an organism depends on
several requirements, if one of these is
present in minimal quantities this will limit
the organism regardless of the abundance of
the others.
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Minerals in the
Soil
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15
10
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0
P
Fe
K
N
Ca
Mg
Limiting Factor = Nitrogen
– No matter how much of the other minerals
you have once you run out of nitrogen
plants can not grow.
– So nitrogen in this example is the limiting
factor.
Some further examples of limiting
factors:
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Oxygen in a billabong
Water in a desert
Light in the ocean depths
Nutrients in the upper layers of the sea
Shelford’s Law of Tolerance
– Organisms have an ecological maximum
and minimum, with a range in between
which represents the “limits of tolerance”.
Too Much or Too Little!
Range of Tolerance
• Every population thrives in an optimal range of
abiotic factors.
• Beyond this range, one finds less and less
numbers of these organisms.
• In an ecosystem, it is harder to represent what this
optimal range is, since a host of factors affect the
survivability of this population.
• Often, the range is shown for each factor, and this
is known as the range of tolerance.
Too dry
Too wet
Just right
Just Right
Too Cold!
Too Hot!
Tolerance Limits
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Tolerance to heavy metals
Variation in ranges of tolerance
Habitat
• A habitat : is an ecological or environmental area
that is inhabited by a particular species of animal,
plant, or other type of organism.
eg
–
–
–
–
–
an ocean,
a lake,
a tree,
a rotting log,
the alimentary tract etc
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Ecological Niche
• The Ecological Niche of an organism describes how
that particular individual "fits" into its ecosystem.
• Within its habitat, it must make use of available
resources, withstand abiotic and biotic factors, with
the help of adaptations
• the role that the individual organism plays in its
nonliving and living environment.
Habitat and Niche
An investigation into the niche of two species of barnacles
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Describe what happened to the distribution/realised niche of Cthamalus
once Balanus was removed.
Why might this change have occurred?
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The wider the
species range of
tolerance the
greater the
potential
geographic range
or distribution
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Specialist species
• Species that have relatively
tightly defined niches and have
a narrow range of tolerance.
• Such species are better off
when their preferred
environment remains stable.
• Pandas are considered to be a
specialist species.
Generalist species
• Species that have broad
niches and tolerate larger
changes in the environment.
• Such species can survive in a
variety of different conditions.
• Humans are considered to be
a generalist species.
• The description of a niche may include
descriptions of the organism's life history,
habitat, and place in the food chain.
A ringtailed possum is a nocturnal
marsupial herbivore that inhabits a
range of forests , woodlands,
shrublands and is adapted to urban
gardens.
Feeding Niches for Wading Birds
Environment:
• The external surroundings including all of the biotic
and abiotic factors that surround and affect the
survival and development of an organism or
population.
• Eg Rocks, minerals, soil, water, air, mountains,
rivers , oceans, plants , animals etc
• Populations: the number of a specific species of
organisms living in a specific habitat at a specific
time.
• eg: population of dolphins in Port Phillip bay
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Community: A group of interdependent organisms living
and interacting with each other in the same habitat.
eg the Port Phillip Bay Community includes populations of algae.
microorganisms, invertebrates, fish , birds, mammals including humans
Dolphins
hunting fish
using sea
snakes!!!!!!
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An ecosystem:
• is a natural system consisting of all plants, animals
and microorganisms (biotic factors) in an area
functioning together with all the non-living physical
(abiotic factors) of the environment .
• Ecosystem = habitat + community
Eg
•a billabong ecosystem
•a river ecosystem
•a desert ecosystem,
•Port Phillip Bay etc
• In order to systematically study and understand
ecosystems- we make both:
– Qualitative observations
• (eg the water temperature is mild )
– Quantitative observations
• (eg the water temperature range is 120C – 220C with an average
temperature of 16 0C etc….)
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• Systematic quantitative measurements or
monitoring enable us to determine…
• Within habitats there are:
microhabitats = small scale differences in abiotic factors
• These variations affect the biotic factors such as
type and distribution of species
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• Some methods of monitoring and
categorisation of abiotic and biotic factors
are very specific or narrow
• These can give us important information about
potential effects on the environment and
ecosystems
– eg rainfall is a narrow measure however it is a
critically important factor which determines what flora
and fauna may inhabit an environment
• Climatic factors: individually and together
are important descriptors of environment
and determinants of the presence and
pattern of life in an environment.
• Climate encompasses the statistics of:
– temperature,
– humidity,
– atmospheric pressure,
– wind,
– rainfall,
– atmospheric particle count and
– numerous other meteorological elements in a
given region over long periods of time.
Mapping individual abiotic climatic factors can reflect biotic patterns
Combining several climatic factors we can classify the Australian
environment in to the following major classification zones
Geomophological factors such as:
• altitude
• topology - lay of the land
(flatness/steepness)
• geology rocks- minerals soils
• etc
Are all abiotic factors that are important
determinants of biotic distribution.
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Australian Elevation Map
Soil Distribution in Australia
• Botanists seeking to understand our vegetation
look for patterns in the distribution of identifiable
vegetation communities.
• The type of plants and their distribution reflect the
underlying geomorphology and climate of the area
and in turn affect the distribution of animals and
other life.
Specht’s Classification of Australian
Vegetation
• Specht developed a system which has become widely used
both in Australia and overseas.
• It is based on three elements:
– Identification of the lifeform of the tallest stratum (or layer) of
plants in an area (e.g., trees, shrubs, hummock grasses or other
herbs).
– Determination of the height and/or type of vegetation in the tallest
stratum (e.g., ‘trees over 30m’, or ‘shrubs, non-sclerophyllous’, etc.).
– Determination of the projective foliage cover of the tallest stratum.
This is the percentage of area which is covered by that foliage (leaves).
Open 30-70%
Closed > 70%
Foliage cover
< 10%
Open 10-30%
Tall closed
forest
Tall Closed
Forest
Tall Open
Forest
Tall
Woodland
Low closed forest & Tall closed
shrublands
Grasslands
Low closed herbfield