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ZONATION AND
POPULATION…read more

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Estimating population sizes
Population ­ all the organisms of one species in a habitat You can capture the species using a pitfall
Community- populations of different species trap. However here are some points about
A quadrat is a square frame that encloses a these methods:
known area.
· sample size effects the accuracy of the
You can use the findings within a quadrat to estimate
estimate larger findings.
When using the capture-recapture method...
You can estimate a population by using the · assume no changes have been made
capture-recapture method. · sampling methods were identical
· You capture a small sample of the population and mark · the marking didn't affect survival
it.
· You put them back and recapture a sample of the
population
Pitfall trap
· Then record how many you have captured that are Soil
marked
Estimate the population size by using:
A Quadrat
Population = number in first sample X no. In second sample
Size number in second sample previously marked cover
jar
food…read more

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Ecosystems and Distribution of
Organisms
REMEMBER!
Ecosystems ­ all the organisms living in Kite diagrams ­ allows you to map the The thickness of the
kite shape shows the
a particular area distribution of organisms in an area. abundance and the
· They are self supporting and maintain The kite diagram below shows the
shape has a centre
line to make the kite
themselves. distribution and abundance of symmetrical
· The only thing outside an ecosystem is organisms along a transect in costal dunes
the energy source e.g. The sun.
Distribution ­ where organisms are HEATHER
found within a particular area. 20%
10%
Transects ­ lines that can be used to 0%
10%
investigate distribution. 20%
MOSS & LINCHENS
% Abundance of organism
20%
To do a transect you need to: 10%
· Place quadrat next to each other all 0%
10%
along in a line 20%
20% MARRAM GRASS
· Count and record the organisms found in 10%
each quadrat. 0%
10%
You can calculate the % cover of the quadrat 20%
Covered and plot the results of a transect in a
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
kite diagram.
Distance along the transect (m)…read more

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Zonation
Abiotic factors ­ all non-living and physical factors
in the environment
For example: light, temperature and water
Distribution is affected by these factors because:
· Different organisms are adapted to live in
certain conditions
· Many organisms can only survive in the
conditions they are adapted to
Zonation ­ is the gradual change in the distribution of
species across a habitat
A gradual change in the Abiotic factors can lead to
Zonation of organisms. For example soil depth could
result in zones where different plants are found.…read more

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Biodiversity
Biodiversity ­ a measure of the variety of life For example: Native woodlands have a higher
in an area biodiversity than forestry plantations as lakes
This includes do to fish farms
· Variation between individuals within a Native woodlands Forestry Plantations
species
Has a variety of tree Has one species of tree
· The number of different species in an area species
· The number of different habitats
The trees are different The trees are all planted at
ages and sizes the same time
Ecosystems with a high level of biodiversity
Variety of plant species There are fewer plant
are healthier as it is more diverse and are able species
to cope better with environmental changes
Variety of habitats Fewer habitats
Natural ecosystems have a higher Variety of animal species Has a Fewer animal species
Biodiversity
than artificial ones.
They maintain themselves without any help Lakes Fish farms
Has many different fish Has one fish species
Artificial ecosystems are created and species
maintained by humans
Has a variety of plant Has fewer plant species
e.g. Fish farms, forestry plantations
species
Has a variety of animal There are fewer animal
species species…read more

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