Energy and Ecosystems Flashcards
What do pyramids of biomass show?
The amount of biomass in each trophic level at a single moment in time
Nearly always pyramidal
What do pyramids of energy show?
The amount of energy available in each trophic level in kilo joules per square metre per year (the net productivity of each trophic level)
Always pyramidal
What is the net productivity equation?
Gross productivity - respiratory loss
Why isn’t all energy transferred to the next trophic level?
- not all of the organism is eaten
- not all of what is eaten is digested (faeces)
- loss via excretion
- respiratory losses as heat
What do pyramids of numbers show?
The number of organisms in each trophic level.
Not always pyramid shaped!
Describe the process of eutrophication
- Leaching of nitrates into water
- Causes an algal bloom
- Competition between algae and underwater plants for light
- Plants not getting light die
- Microorganisms (Saprobiots) decompose dead plants
- Microorganisms respire using up oxygen in the water
- Fish/Animals die due to lack of oxygen
Describe the nitrogen cycle
- Protein/Amino Acids/DNA into ammonia
- by Saprobiotic microorganisms
- Ammonia into nitrite
- Nitrite into nitrate
- By nitrifying bacteria
- Nitrates converted into atmospheric nitrogen by denitrification
- Nitrogen from the atmosphere converted to ammonia
- By nitrogen-fixing bacteria/microorganisms in the soil
How does Intensive rearing increase energy conversion thus increase productivity?
- movement is restricted so less energy is used in muscle contraction
- environment can be kept warm in order to reduce heat loss
- feeding can be controlled so that animals receive the optimum amount
- predators are not present, easier survival
What are the advantages of biological control of pests?
- Specific
- Control organism can reproduce itself
- Pests do not become resistant
What are the disadvantages of biological control of pests?
- Not as fast acting
- Control organisms may become pests
- Not all of the pest is removed
What are the advantages of chemical control of pests?
- Quick
- Used up, none left over
- No chance of it becoming a pest itself
- Can be easily applied an distributed
What are the disadvantages of chemical control of pests?
- Can become resistant
- Expensive
- Can effect non-target species
What are the advantages of using integrated systems to control pests?
- Combining can reduce pest numbers even more
- Can reduce costs (less chemicals needed)
- Specific and only needs one application (biological)
- But also quick and reduces the chance of the biological agent becoming a pest itself (chemical)
