Download module 4 4.2.1 biodiversity

Module 4 – 4.2.1 Biodiversity
By Ms Cullen
Terminology
Try and define the following terms
used when studying the
environment.
Biosphere
• The outermost part of the planet’s shell –
including air, land, surface rocks and water –
within which life occurs.
Ecosystem
• Ecosystems are dynamic interactions between
plants, animals, and microorganisms (biotic) and
their physical environment (abiotic) working
together as a functional unit. The abiotic
environment includes climatic and edaphic (soil
or water composition). Ecosystems will fail if they
do not remain in balance.
eg a coral reef
Species
• This is the fundamental unit of classification.
• A species is a group of similar individuals (in
appearance, anatomy, physiology,
biochemistry and genetics) that can
interbreed and produce fertile offspring.
Habitat
• Is the place where a particular species lives
and grows. It is essentially the environment –
at least the physical environment – that
surrounds (influences and is utilised by) a
species population.
Biodiversity
• This is the variation of life forms within a given
ecosystem, biome or the Earth.
• It includes all different plants, animals, fungi
and microorganisms species.
• Biodiversity is often used as a measure of the
health of biological systems.
It is estimated that there are 13 – 14
million different species on Earth.
We have recorded about 2 million of these.
Why have we only recorded such a small number?
Where do you think the most species rich ecosystems
are?
Possible Proportions of Total Species
%
0.4
1.6 1.6
1.6
3
3
Vertebrates
4
Algae
4
Protozoans
Molluscs
6
Plants
Bacteria
Viruses
8
Nematodes
Arachnids
65
Fungi
Insects
GLOBAL BIODIVERSITY
VALUE: a map showing
the distribution of
some of the most
highly valued
terrestrial biodiversity
world-wide
(mammals, reptiles,
amphibians and seed
plants), with red for
high biodiversity and
blue for low
biodiversity.
Measuring the variety of
nature & selecting priority
areas for conservation
What is sampling?
Taking measurements of a limited number of
individual organisms present in a particular area
Sampling – Random or
Non-random?
• Random – means individuals are selected by
chance.
•
-
Non- random techniques include:
Opportunistic (not very representative)
Stratified (sub- groups eg male or female)
Systematic (usually a line or belt transect)
Reliability
• Sampling never gives a complete
representation of organisms in a habitat
because:
• Sampling bias
• Chance
Methods for Sampling Plants
Equipment used for Sampling Plants:
•
•
•
•
Frame quadrats - usually 0.25m2, 0.5m2, 1m2
Permanent quadrats.
Point quadrats (pin frame).
Line transect – only species touching transect
recorded.
• Belt transect – area sampled between 2 line
transects.
• Profile transect – includes height variations of
species.
Randomising samples:
• Observe all species present and count how many
individuals of each species there are within each
sample.
• Take samples at regular distances across a habitat.
• Use random numbers generated by a computer or
random number table to plot coordinates within the
habitat.
• Select coordinates from a map of an area and use
GPS to find exact position within habitat.
How many samples?
• This will depend on size of habitat and time
available.
• If a habitat is uniform, valid results can be
obtained by using 5 quadrats.
• If a habitat is not uniform then at least 10
quadrats need to sampled.
• The more species abundant a habitat appears
the more quadrats should be done to give a
clear picture.
Species Evenness
(or Species Density)
The number of individuals of a
species within a given area.
Calculating Species Evenness
Quadrat
1 2 3 4 5 6 7 8 9 10
No of
plantain
0 3 0 1 0 0 5 2 0 1
• A survey gave the following results for a species of plant –
plantain, using a 0.25m2 quadrat.
• Ten quadrats were placed so a total area of 10 x 0.25 = 2.5m2
• Total amount of plantain found in this area is 12.
• Therefore the species evenness is 12 = 4.8 per m2
2.5m2
Species Richness
The number of different species
in a given area
Species richness and species evenness will
affect biodiversity:
• Habitat x and y both contain 2
different species and 30
individual organisms.
• Species richness in the 2
different habitats is the same –
2.
• In habitat y the individual
organisms are more evenly
distributed between the 2
species therefore it has greater
species evenness.
Habitat x
Habitat y
Species 1
28
15
Species 2
2
15
Total
30
30
The greater the species richness
and species evenness in an area,
the higher the biodiversity.
Species Cover
A measure of the proportion of
ground covered by the species.
This is particularly useful when
dealing with large numbers of small
plants in a quadrat – too many to
count.
Species Frequency
A measure of the probability of
finding a given plant species within a
randomly placed quadrat in a given
area.
eg if a species only appears once in
10 quadrats it has a Species
Frequency of 10%
Diversity is measured using
Simpson’s Index of Diversity
• Simpson’s Index of Diversity (D) takes into
account both species richness and evenness.
• It can be calculated using the following formula:
D = 1 – [Σ(n/N)2]
n is the number of individuals of a species (or % cover of plants).
N is the total number of all individuals of all species (or % cover for
all plants).
Σ is the sum
Look at Tables 1 & 2 in OCR AS Biology book P.199
- 200.
Using Simpson’s Index of Diversity
• A high value will indicate a diverse habitat.
• A low value reflects a habitat dominated by a
few species, therefore it has a low biodiversity.
Carry out Practical Activity 31
Calculating Species Diversity
and complete Qs
Activity 31
Species
Total no. of individuals N =
Sum Σ(n/N)2=
1–Σ=
No. of individuals
(n)
n/N
(n/N)2
Recording Species
• Use scientific names – binomial latin names.
• The first letter of the first name (Genus)
should be a Capital letter, all other letters
should be lower case eg Calluna vulgaris.
• You must check spelling carefully, incorrect
spellings will loose marks!
Scientific Diagrams
• Clear, continuous lines for your sketch, use a
SHARP pencil!
• NO SHADING!
• Diagram should cover at least 50% of space
given.
• All label lines should be straight – use a ruler.
• Label lines should touch the structure you are
identifying.
• Label lines should not have arrows on the end.
Sampling Animals
•
•
•
•
•
•
•
•
Sweep nets
Tree – beating
Pitfall traps
Pooters
Tullgren funnel
Light trap
Capture and release
Longworth trap for small mammals