Zusammenfassung der Ressource
Population Size &
Ecosystems
- Population
graphs
- Oscillations
Anmerkungen:
- Predator-prey relationship causes both populations to oscillate
- Sigmoid growth: usual
pattern of growth= 1
step growth curve
- Density-Dependent
Factors
- Environmental factors that
have more effect if the
populations in a given area
is large
- Disease, parasitism,
predation, depletion of
food supply
- Biotic
- Density-Independent
Factors
- Abiotic
- Effect is the same regardless
of population size
- Temperature
- Ecosystems: A characteristic community of
interdependent species interacting with
the abiotic components of their habitat
- A sequence of
energy changes
- Abundance: The number of individuals
in a species in a given area or volume
- Capture-mark-recapture
- Kicksampling
- Quadrat
- Kite diagrams
- Distribution: The area/volume in which
the organism of a species are found
- Transect
- Belt transect
- Line transect
- Food Chains
- Energy leaves the
system as heat
- Length is
dependent on
Anmerkungen:
- -The energy that enters the food chain at the 1st trophic level
-Efficiency of energy transfer between trophic levels
-Predator and prey population
-Size of the ecosystem: larger=longer
- Photosynthetic efficiency: A measure
of the ability of a plant to trap light
energy
Anmerkungen:
- -Wrong wavelength of light
-Light can be reflected
-Light can be transmitted straight through the leag
- Efficiency of energy transfer= Energy incorporated into biomass after
transfer/ Energy available in biomass before transfer
- There is a loss from the
food chain at each level
Anmerkungen:
- -There is energy in molecules that are egested
-Energy is lost as heat due to respiration
- Energy remains in molecules in parts of animal that may not be eaten e.g. horns
- Ecological Pyramids
- Pyramid of Numbers
- Does not take into account
the size of the organisms
- Area of the pyramid bar is
proportional to the total
number at each trophic level
- Pyramid of Energy
=feeding relationships
- Area of bar decreases =energy loss from
the ecosystem
- Easy to compare the efficiency of
energy transfer between trophic levels
- Pyramid of
Biomass
- Inverted pyramid
- Hard to measure accurately
- Succession
- Climax community
equilibrium
- GPP=Respiration
- Constant quantity of humus
- Complex food web
- Bare rock ---> Deciduous forest
- 1. Algae and lichen colonise the rock=pioneer
community
- 2. Formation of primitive soil
- 3. As soil develops, herbaceous plants outcompete mosses.
Seeds that can germinate in direct sunlight are favoured
- 4.Tall grass starts to grow. Shade-tolerant species are established
- 5. Soil thickens as plants and animals start to die
- 6. Shrubs outcompete herbaceous plants
- 7. Soil deepens which increases the quantity
of minerals and humus in the soil
- 8. Large trees outcompete shrubs
- Secondary succession
Anmerkungen:
- Same sequence as primary succession but it's more rapid
- Factors affecting
succession
- Human interference
- Over-grazing
- Farming of land
- Deforestation
- Migration
- Arrival of
spore, seeds
and animals
- Competition amongst organisms
- Intraspecific-between
individuals of the same species
- Interspecific- between
individuals of different species
- Human Impact on
the Carbon Cycle
- Deforestation
- Climate
Change
- Agriculture is
vulnerable
- Global
Warming
- Enhanced greenhouse gas effect
- Human Impact on
the Nitrogen Cycle
- Fertiliser
effects
- Increase in
nitrates
- Decrease in species diversity
- Harms all ecosystems
- Eutrophication
- Sewage and
fertilisers leak into
bodies of water
- Carbon footprint
- Nitrogen fixation
- Nitrification
- Ammonification
- Denitrification