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How biodiversity may be considered at different levels
To include habitat biodiversity (e
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sand dunes, woodland, meadows, streams), species biodiversity (species
richness and species evenness) and genetic biodiversity (e
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different breeds within a species)
Biodiversity is the range of species in an area, the range of habitats and the variety of alleles
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A habitat is the area in which an organism lives
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In general, the greater the habitat biodiversity,
the greater the species biodiversity will be within that area
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Species biodiversity includes species richness and species evenness
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The more the species evenness and the species richness, the greater the species biodiversity
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The genes may be the same for all individuals within a species
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The more variety in alleles, the greater the genetic biodiversity
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How sampling is used in measuring the biodiversity of a habitat and the importance of sampling
To include how sampling can be carried out i
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random sampling and non-random sampling (e
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opportunistic,
stratified and systematic) and the importance of sampling the range of organisms in a habitat
It is difficult to count every organism to measure the biodiversity of a habitat as not all of the species may have been found,
some organisms may be extinct and new species are being formed as evolution is on-going
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This is a representative group of organisms that are selected from a population
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Random sampling is an unbiased method as the observer doesn’t decide when and where to take the measurements
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Random numbers taken using a random number
generator is used to determine the x and y coordinate on the grid
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The sample is repeated many times at
different times of the year
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Stratified sampling is where the population is divided into strata based on a particular characteristic e
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gender
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Systematic sampling identifies different areas within an overall habitat (changing in species over different areas) which are
then sampled separately
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A line transect is where a line is measured along
the ground between two poles and samples are taken at regular intervals
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Sampling is important because it informs scientists of the species present and gives an idea of the biodiversity in the habitat
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Sampling the range of organisms in a habitat is important because it prevents sampling bias and chance
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Practical investigations collecting random and non-random samples in the field
Animals can be collected for study later but must be handled carefully and used for as short a period of time as possible and
then released:
 A pooter – Catches small insects by sucking on a small mouthpiece which draws insects into the holding chamber via the
inlet tube
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 Sweep nets – Catch insects in long grass
 Pitfall traps – Catches small, crawling invertebrates
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The trap is left overnight so nocturnal species are also sampled
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A white cloth is stretched out under the tree/bush and it is shaken
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The river bank and bed is kicked to disturb the substrate
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Plants are normally sampled using a quadrat:
 Point quadrat – Frame with long pins pushed at set intervals along the bar
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 Frame quadrat – Square frame with grid
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To study how the presence and distribution of organisms across an area of land varies, the quadrats can be placed
systematically along a line or belt transect
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The more species there are, the higher the species richness
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A list should be
compiled of each species identified
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To accurately identify organisms, identification keys are often used which contain images/questions to identify organisms
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The more
equal the species, the higher the species evenness
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Populations that are similar in size or density represent an even community so has a high species
evenness
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Population of plants using a frame quadrat is measured by percentage cover, frequency or density of each species
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A mean of the individual quadrat results should be calculated
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Population size may be measured using the capture-recapture method
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After a period of time, the
individuals are recaptured
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The greater the number of marked individuals recaptured, the smaller the population
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g
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They
have a direct effect on the living organisms that
reside there
...


pH
pH
Temperature
°C
Oxygen content in water
mg dm ³
Measuring abiotic factors is advantageous because rapid changes can be detected, human error in taking a reading is
reduced, a high degree of precision can often be achieved and data can be stored and tracked on a computer
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Simpson’s Index of Diversity is a measure of biodiversity or species diversity which takes into account both species richness
and species evenness
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The higher the index, the more diverse the habitat
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If there is a change in one
species, it is likely to affect the whole habitat
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Habitat feature
Number of successful species
Nature of environment
Adaptations of species to environment
Type of food web
Effect of environmental change on ecosystem

Low biodiversity
Relatively few
Stressful/extreme with relatively few ecological niches
Relatively few species, often with specific environmental adaptations
Relatively simple
Major effects

Although some habitats of low biodiversity are unable to support large species diversity, the organisms present can be highly
adapted to extreme environment of the habitat
...
It is therefore important to
conserve some habitats with low biodiversity, as well as those with high biodiversity, in order to conserve rare species that
may be too specialised to survive elsewhere
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To ensure the Simpson’s Index of Diversity is as
accurate as possible, a random sample should be taken, an identification chart should be used, the sample must be taken by
the same people/person in the same way, the sample should be taken at different times of the year and the sample should
include species that are larger than the quadrat
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Polymorphic genes have more than one allele
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This ensures the basic structure of individuals within a
species remains consistent
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The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within a population
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All members share the same genes but may have different
versions of the same gene (alleles) creating genetic biodiversity
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Species with greater biodiversity are likely to be able to adapt to environmental changes so less likely to become extinct
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Genetic biodiversity decreases when the number of possible alleles decreases
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g
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The factors affecting biodiversity
To include human population growth, agriculture (monoculture) and climate change
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 Climate change – large amounts of carbon dioxide and other pollutants released from deforestation and the burning of
fossil fuels increasing global temperatures, rising sea levels causing saltwater to flow to rivers reducing biodiversity in

freshwater habitats, melting polar ice caps leading to extinction of organisms living in region, causing extreme change sin
weather patterns and changing insect life cycles and populations
The ecological, economic and aesthetic reasons for maintaining biodiversity
Ecological, including protecting keystone species (interdependence of organisms) and maintaining genetic
resource, economic, including reducing soil depletion (continuous monoculture) and aesthetic, including protecting
landscapes
Ecological reasons
 Organism are interdependent on others for their survival – removal of one disrupts food chain
 Keystone species – Species that maintain structure of ecological community
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Other plant species will be outcompeted as a result of competition from crop species which disrupts the food chain and reduces soil quality over time so
plants cannot grow
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Reduces ability to grow crops leading to resource- and economicdependence on other nations
 Sustainability – non-sustainable resource will eventually run out, even replanting forest areas will not be as biodiverse as
the established habitats they replace
 Undiscovered species – undiscovered species may be chemically or medically used and may become extinct before they
are discovered if there are large-scale losses of habitat and biodiversity
 Soil depletion – caused by continuous monoculture, reducing diversity of soil nutrients and making ecosystem more
vulnerable
 Abiotic stresses – high biodiversity protects against abiotic stresses
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Sustainable development – economic development that meets the needs of people without limiting the ability of future
generations to meet their needs
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It’s sometimes necessary to conserve in situ because it
maintains not only the genetic diversity of species but also the evolutionary adaptations that enable the species to adapt to
changing environmental conditions e
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pest populations and climate change
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It is generally cheaper than ex situ conservation
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It creates areas of refuge
within which populations can build up and repopulate adjacent areas
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It doesn’t prevent fisherman from visiting the area
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It is actively managed through controlled
grazing, restricted human access, controlled poaching and the culling or removal of invasive species (not native to area and
has negative effects)
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It’s sometimes necessary to conserve a species ex situ
because its natural habitat may be lost or destroyed due to climate change or deforestation and it can allow protection
against predators and hunters for animals and grazers and plant collectors for plants
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Breeding ex situ maintains the
gene pool allowing genetic diversity
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Seeds are less susceptible to disease, pests and environmental change and it prevents fertilisation by undesired
pollen
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Conservation in zoos including captive breeding programmes aims to create a stable, healthy population of a species which
can then be reintroduced back into its natural habitat
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International and local conservation agreements made to protect species and habitats
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Its
aim is to ensure that international trade in specimens of wild animals and plants does not threaten their survival
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The agreement covers all
ecosystems, species, and genetic resources
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It makes conservation a part of normal farming and land management
practice

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