Flows of energy and matter

1st law of thermodynamics

conservation of energy -energy is neither created or destroyed

IN open system - once energy has entered it will never increase = energy has to keep enetering for system to function

2nd law

in isolated system entropy (disorder) tends to increase

in ecosystem this means less energy is available as we move up trophic level

plants only convert 1-2% of obtained energy and about 10% is passed from trophic level to another - left over is used for metabolism, to do work or lost as heat

entropy

degree of disorder in a system

as energy transformations are never 100% = there’s energy thats unavailable to work = system goes from stable to less order/chaos

efficiency

useful output/input

primary productivity

conversion of light energy to chemical energy within plant cells

Gross primary productivity (GPP)

sugar produced

Net primary productivity (NPP)

biomass available/ difference between rate of photosynthesis and respiration

NPP = GPP - Respiration (sugar used)

uses of glucose in plants

used for growth, maintenance and reproduction and energy lost as heat or remainder is deposited and stored as dry mass = potential food for consumers

what affects productivity

availability of resources for photosynthesis and diversity (ensures efficient use of resources and increases stability)

secondary productivity

production of organic matter by the consumers

Gross Secondary Productivity (GSP)

total energy assimilated by consumers

GSP =food eaten- fecal loss

fate of energy for consumers

assimilated food energy - used to power life processes

fecal waste - passes through organism and released as feces

Net Secondary Productivity (NSP)

total gain of energy or biomass in consumers

NSP = GSP - R

primary vs secondary productivity

GPP = glucose made

GSP = energy assimilated by consumers

maximum sustainable yield

max flow of a resource so that the population does not decline - equivalent to NPP or NSP