Unit 6 - Ecosystems Flashcards
Open ecosystem
When living things can move between ecosystems
Closed ecosystems
When living things cannot easily move between ecosystems e.g. islands
Biotic factors affecting ecosystems
Predators
Food supply (prey)
Disease
Cooperation between species
Competition between species
Abiotic factors affecting ecosystems
pH
Conc of pollutants
Temp (climatic)
Moisture/ rainfall/ relative humidity
O2 level
Soil type (edaphic)
Light intensities
How does low light intensity affect the ecosystem
Plants develop photosynthetic pigments that require less light
Grow larger leaves
Reproductive systems that only work in optimum light intensities
How does temp affect the ecosystem
Temp has the biggest effect on enzymes in the organisms that live in the ecosystem
May trigger migration/ hibernation
Dormancy/ leaf fall/ flowering in plants
How are ecosystems organised
In trophic levels
Producers in an ecosystem
Lowest trophic level
Involves autotrophs, chemotrophs and photoautotrophs
Autotrophs
Convert energy from environment into complex organic matter, then are used as respiratory substrates or for growth
Types of changes in ecosystems
Cyclical - repeated change e.g. seasons, day/night
Directional - in one direction e.g.global warming, erosion
Unpredictable/ erratic - no rhythm or constant direction e.g. volcanic eruption
Components of an ecosystem
Habitat
Population
Community
Community
All the populations of diff species who live in some place at a given time, who can interact w/ each other
How is biomass lost
Cellular respiration - conversion to inorganic molecules such as CO2 and H2O
Excretory materials
Indigestible matter
Not everything is fit for consumption e.g. bones
Transferred at metabolic heat (movement)
Loss of biomass in endotherms vs ectotherms
Ectotherms use less energy in maintaing body heat so there is more biomass availabe
Why is the producer efficiency v. low
Approx 90% of light is reflected, unusable wavelength and transmitted through leaf
Limiting factors
Energy used for photosynthetic reactions
Succession
Progressive change in the structure and species composition in a community
Affects vegetation first but then brings about corresponding changes in bacteria, fungi, insects, birds and mammals
Pioneer species
Species that begin the process of succession, often colonising an area as the first living thing there
Use of transects
Look for changes in vegetation across a habitat
Line transect
At reg. intervals
Note of which species are touching the tape
Belt transect
At reg. intervals
Place a quadrat next to the line (interrupted belt transect) or move the quadrat along the line (continuous)
Used to sample succession
Estimating pop. size
Mean number of a species in a quadrat/ fraction of the total habitat area covered by a single quadrat
How did cane toads rapidly increase in population?
- Fast moving -> rapidly disperse to find new sources of food in areas with reduced competition and less predators (these are selection pressures) -> interbreed and produce fast, long-legged offspring -> move faster into new territory
How did the prickly pear change in population in Australia (increase/decrease)?
Increase:
- Conditions in Australia similar to native environment
- Predator free environment
- Fast growing
Decrease:
- Introduction of moth that controlled it
