Energy and Ecosystems Flashcards
Ecosystems
The abundance and distribution of organisms are controlled by biotic and abiotic factors
What are biotic factors?
Living
What are abiotic factors?
Non-living
Population
All the organisms of a single species in a habitat
Community
All the organisms of all the species in a habitat
Habitat
The place where an organism lives
Niche
The role of a species in an ecosystem
Trophic level
Each stage of the food chain
Trophic level examples
- Producer
- Primary consumer
- Secondary consumer
Interspecific competition
Between different species
Intraspecific competition
Within a species
Biotic factors examples
Other animals or plants
Abiotic factors examples
Water, soil, air, sunlight, temperature
Gross primary production
- The total amount of energy made by producers
- Per unit area per unit time
Respiratory losses
The energy used by organisms for respiration
Net Primary Production formula
NPP = GPP - R
Net primary production
NPP = Gross primary production - Respiratory loss
What is the net primary production?
The amount of chemical energy a producer stores as biomass per unit area per unit time
Net production of consumers
I - F + R
Net production of consumers what is F
The chemical energy lost to the environment in faeces and urine
Net production of consumers what is I
The chemical energy store in ingested food
Net production of consumers what is R
The respiratory losses to the environment
Sun energy transfer to producer
- very low
- wrong wavelength
- light strikes non photosynthetic region
- light reflected
- lost as heat
Producer energy transfer to primary consumer
- low
- respiratory loss
- plant uses energy for metabolism
- lost as heat
- not all plant eaten
- some food not digested
Primary consumer energy transfer to secondary consumer
- low
- respiratory loss
- primary consumer uses energy for metabolism
- lost as heat
- not whole animal is eaten
- some food not digested
When is energy transfer especially low?
- Old animals (stop growing)
- Herbivores (more poo)
- Endotherms (warm blooded)
How to increase energy transfer efficiency in plants
1 - Shorten food web
- reduce competition so the plant has more energy to create biomass
- Herbicides to kill weeds
- Fungicide to reduce fungal infections
- Insecticide kill pests
2 - Fertilisers
- prevent growth being limited by lack of nutrients
How to increase energy transfer efficiency in animals/livestock
3 - Reduce respiratory loss
- restrict movement (less energy used to make biomass)
- keep warm in winter
4 - Slaughter animal whilst still growing
5 - Keep predators away
6 - Controlled diet to increase % of food digested
How to increase energy transfer efficiency in animals/livestock and plants
7 - Artificially select organisms with a high yield
Ways of measuring biomass
Dry biomass and mass of carbon
How to measure dry biomass
- sample of biomass is warmed on a scale until constant mass (all water evaporated)
- temperature must be low to avoid combustion
- amount of water in samples varies a lot so dry biomass gives a more representative sample
- kg.m^-2
How to measure mass of carbon
- organisms made up of organic compounds
- mass of carbon is a good indicator for biomass
- difficult to measure
- carbon is usually about 50% of the dry biomass
- kg.m^-2.yr^-1
How to calculate energy stored in biomass
- calorimetry is used to estimate the amount of energy stored in dry biomass
- burn sample completely
- heat a known volume of water
- measure temperature change of water
- calculate energy release
How are ammonium ions converted into nitrites
Nitrification
How are nitrites converted into nitrates
Nitrification
How are nitrates converted into nitrogen
Denitrification
- anaerobic conditions
How is nitrogen gas made usable
Nitrogen fixation
- legumes
- by bacteria in root nodules
Which form of nitrogen is usable by plants and animals
Nitrates
How do plants and animals use nitrates
Proteins/DNA
What happens to nitrogen when plants and animals die
Saprobiontic microbes (decomposers) digest dead/organic matter using extracellular enzymes
How are ammonium ions reformed?
Ammonification
What are sources of phosphate ions?
Rocks
How are phosphate ions removed from rocks?
By erosion and weathering into rocks and soil
How do plants and animals get phosphate ions?
Plants from soil, animals from eating plants
How are phosphate ions recycled back to the soil?
Saprobiontic nutrition
How do plants, animals and decomposers use phosphorus?
ATP/DNA
How are nutrients recycled
Microorganisms break down large organic compounds into small soluble inorganic compounds which can be absorbed by producers
Saprobionts
Type of decomposers that digest food by saprobiontic nutrition
Saprobiontic nutrition
Digestion of dead organic matter by extracellular enzymes (products are absorbed by producers)))
Mycorrhizae
Fungi that grow in a mutualistic relationship with plant roots
Benefits of mycorrhizae on the plant
- Increase in surface area of the plant
- increases absorption of minerals and water
Natural fertiliser
- Contain nitrogen and phosphorus in organic compounds
- Still need breaking down by saprobionts
Artificial fertiliser
Inorganic chemical compounds that contain nitrogen and phosphorus (water soluble)
Leaching
- Water soluble compounds are washed off land by rain
- More common in artificial fertilisers
Eutrification
- Nitrite/phosphate ions leach into fresh water
- Algal bloom
- Blocks out light
- Plants can’t photosynthesise and die
- Saprobionts breakdown dead plants
- Use up all oxygen
- Fish die
Harvesting crops/livestock
- Removes N and P from cycles
- Soil N and P get depleted
- Add fertiliser to replace N and P
- Too much fertiliser can change water potential
Benefits of natural fertilisers
- Aerate soil
- Less leaching
- Combine a wider range of elements
- Consume less energy
