Enrgy Flow And Nutrient Cyles 4.3 Flashcards
What is net productivity?
The amount of energy available for the next tropic level.
Equation for net productivity…
Net productivity= gross productivity - respiratory losses
What is a natural ecosystem?
An ecosystem that hasn’t been changed by human activity
What does intensive farming involve…?
Changing the ecosystem by controlling abiotic or biotic factors E.g. The presence of pests, availability of water. To make it more favourable for crops or livestock.
How does intensive farming increase productivity?
Increase the efficiency of energy conversion, more energy used for growth.
Removal of growth limiting factors
Increase energy input
Environmental issues with using chemical pesticides?
Directly affect non pest species
Indirectly affect non pest species, e.g. Eating primary consumers that contain the pesticide
Also very expensive
Environmental issues with using biological agents…
Natural predators may become pests themselves
Can affect other non-pest species
Less cost effective than chemical pesticides (affect long term not short term)
What are integrated systems?
Using both biological agents and chemical fertilisers
What are natural fertilisers?
Contain organic mature: manure
What are artificial fertilisers?
Inorganic, contain pure chemicals as powders or pellets
Environmental issues with fertilisers?
Wash into rivers (eutrophication)
Changes Blanche of nutrients, too much may cause other crops to die
An example of a natural sink…
Tree
What is gross productivity?
When the rest of the available energy is taken in (40%)
