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Summary - Biodiversity (YGE01)
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The different ways of defining biodiversity in terms of genetic, species and ecosystemdiversity and the merits of each
Biodiversity: Refers to plant (flora) and animal (fauna) species found in ecosystems. the
variety of plant and animal life in the world or in a particular habitat, a high level of which is
usually considered to be important and desirable.
Ecosystems: Communities of plants and animals (biotic) interacting with non-living (abiotic)
components of their environment (air, water, soil) working as a natural system. The biotic
and abiotic components are linked through nutrient cycles and energy flows. On a global
scale, ecosystems are referred to as biomes
different biomes of the world?
● Tundra, savanna, desert, Mediterranean vegetation, taiga, montane, ice sheet
and polar desert, steppe, tropical rainforest
Genetic diversity Differences within species
Species Diversity Differences between species
Ecosystem Diversity How species operate together across ecosystem
● Though it has been estimated there are around 10 million species on planet earth
(from bacteria, to higher plants and humans), only 1.4 million have been
discovered so far
● 99% of all species that ever lived are now extinct
● Biodiversity is often used as a measure of the health of biological systems
What are the advantages and disadvantages of the different measures?
Advantages Disadvantages
Genetic ● Strengthens ability of ● can be lost when populations get
diversity species and populations to smaller and isolated, which decreases
resist diseases and pests a species' ability to adapt and survive
● Accurate picture of ● Needs high level biological skills to
diversity analyze DNA
● Explains how isolated
groups have adapted
,Species ● Greater biodiversity in ● Prone to extinction
Diversity ecosystems, species, and ● Areas need to be of similar size
individuals leads to ● Many undiscovered species may be
greater stability. microscopic and might skew
● Good general measure biodiversity index based on species
● Better if a range of numbers
indicator species used
● Better to sue taxonomic
diversity
Ecosyste ● Complex as neds to ● Difficult to place boundaries
m measure interaction of ● Need consistent set of criteria
Diversity species in their demarcate an ecosystem
environment and with
each other
● Useful when assessing
areas to protect as has
wider focus
The processes and factors that influence biodiversity (climate limiting factors, isolation and
the role of endemism, age and area, human activity and actions)
What factors influence biodiversity?
- climate : altitude, latitude, temperature, amount of light
- Rate of nutrient cycling
- endemism - when a species is only found in one location
- Growth of human population
- Hunting and direct exploitation of flora and fauna
- Size of the area and topogra[hy
- The level of recording of species within the region
- Anthropogenic effects such as pollution, clearance for agriculture
Explain the factors influencing biodiversity
Factor How does it influence biodiversity
Climate limiting - Equatorial areas have high levels of warmth, sunlight and
factors/latitude precipitation - year round productivity
- In tropical desert areas, lack of rainfall becomes a limiting
factor in plant and animal growth so restricting biomass
and biodiversity
- Towards the poles lack of sunshine and warmth are
limiting factors, so biodiversity is low
, isolation Because islands are physically isolated, evolution often leads to
new species and hence high (and unique or endemic) biodiversity
Endemism mountainous , isolated areas can experience a simi;ar process
with the additional factor of altitudinal zonation: as
temperatures, season length and precipitation levels change up a
mountain side numerous different environments exist at different
altitudes each with their own species types
Age and area Large areas, such as Australia, inevitably contain more species
than small ones. Places that had remained relatively unchanged
for millions of years, especially when physically isolated
Human activity and Today, human interference is an important factor. Urbanization,
actions expansion of farming, deforestation, pollution, tourism, mining
and climate change can all destroy or degrade ecosystems and
reduce biodiversity. THese threats vary spatially. Humans can
also protect biodiversity by conservation and preservation - but
only very rarely can they restore lost biodiversity
The global distribution of terrestrial biomes is related to climate, but local factors (altitude,
soils, drainage) also play a role
NPP (Net primary productivity) = Gross primary productivity - energy lost via respiration
GPP = rate at which plants photosynthesise measured in grams per sq/m per year
Rainforests have a higher NPP because there are fewer limiting factors (climate is warm with
higher rainfall all year round)
How does atmospheric circulation affect the location of biomes?
Rainforest around the equator - most insolation - hottest - hot and moist air - low
pressure
Descending arm in Hadley cell - hot and dry - high pressure - deserts
Grassland - the result of ITCA moving North and SOuth bringing in rainy seasons
Low pressure and rising air of Ferrel cell - temperate grassland - good amount of rainfall
and is temperate because it does receive sunlight but cooler
Polar cell - tundra and cool desserts
,
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