Module 6 Ecosystems Flashcards
What is an ecosystem?
It is the interaction of all living things and non-living things in an area.
What is meant by a dynamic ecosystem
An ecosystem that changes all the time
State some abiotic factors
- Water: affects photosynthesis
- Light: affects photosynthesis
- Oxygen levels: affects respiration
- Temperature : enzyme activity
- Edaphic soil factors: type of soil and ph of the soil
State some biotic features
- Competition
- predation
- new diseases
What are the biotic and abiotic factors in a rock pool
Biotic
-competition
Abiotic salinity ph water light oxygen levels
biotic and abiotic factors for a large tree
biotic
predators, disease, competition
abiotic
ph, soil, water, oxygen, light
What are the biotic and abiotic features in a playing field
Biotic competition, humans
Abiotic
light, water, oxygen, soil
What is a food chain
they show how energy is transferred through an ecosystem
What is biomass
Mass of living material in the area
How do we measure biomass
- use a calorimeter
- collect the sample
- kill the organisms
- place into an oven at 80 degrees (to ensure we remove the water by evaporation)
- check the mass throughout
- then when the mass stays the same that is the biomass
What is biomass in animals measured in
gm-2
What is biomass in marine animals measured in
gm-3
What is the equation to work out net productivity
net productivity= gross productivity- respiratory loss
what is the equation to work out %efficiency of energy transfer
% = net productivity of trophic level/net proudcity of previous trophic level x 100
How do we lose energy down a food chain?
- some energy is the wrong wavelength, is reflected or just passes through
- some parts of the plant like bark can’t photosynthesise
- some parts of the animal-like bones may not be eaten by consumers
- some parts can’t be digested
What is net productivity
it is the amount of energy available for the next trophic level
How do we control energy flow through ecosystems
Using herbicides- this reduces competition
Fungicides- kill fungus so more need can be used for growth than fighting of disease
using insecticides- means less biomass is lost, so they can grow
Natural predators- can eat pest species, so crops lose less energy
Rearing livestock intensively- for example animals are kept warm, movement is restricted, may be given feed that is higher energy (so more good food), slaughtered before they reach adulthood , young animals use loads of energy for growth
What are the stages of the carbon cycle
BTW explain each one
Photosynthesis
Decomposition: break down carbon by secreting enzymes, they then absorb products of digestion by feeding on dead matter (saprobiotic nutrition)
Respiration
Combustion: fossil fuels
Volcanoes
Weathering: can cause carbonates from rock to be released into solution like groundwater
Absorption from sea
What are the stages of the nitrogen cycle
BTW explain each one
Nitrogen fixation: nitrogen from the atmosphere is converted into ammonia by azotobacter (free living) or rhizobium (in legumes) they have a mutualistic environment. Can also be made by the haber proces or lightning.
Ammonification: nitrogen compounds from dead organism turned into ammonia by decomposers. This forms ammonium ions (done with decomposers)
Nitrification: Nitrosomonas changes ammonium ion into nitrites. Then nitrobacter changes it from nitrites to nitrates .
Denitrification: nitrates from soil are converted into nitrogen gas by denitrifying bacteria. Happens in anaerobic conditions water logged soils
What is succession
Process in which ecosystem changes over time
What happens during primary succession
Start with bare rock
pioneer species seeds are blown in the wind
the harsh conditions (limited water, few minerals, no soil, high light intensity, flucating temperatures) mean that only pioneer species can grow (marram grass, lichens, shrubs of calligonum
The lichens die, decompose and form thin soil. Species like mosses can now grow because they have outcompeted the lichen
Larger plants that need more water grow start to grow. These out compete the mosses. These plants will die then decompose making the soil more nutrient rich.
Shrubs, ferns and new trees grow which outcompete grass. At this point diversity increases
The soil is deep and rich enough so it can support large trees. This is the dominant species and a climax community is formed
What happens during secondary succession
Happens on land that has been cleared of plants but soil remains
Due to a forest fire or human activity
Pioneer species are larger
How do we know what climax community will form
It depends on the temperature
