Global primary production- FI Woodward Flashcards
where is the primary CO2 source released from humans from?
from fossil carbon fixed by prehistoric photosynthesis
what do natural systems act as?
sink for CO2 human emissions
what is gross primary production (GPP)?
- rate of production of chemical energy
- net photosynthesis
- photosynthetic conversion of solar radiation to produce ATP and NADPH (CO2 fixation)
- chemical energy in metabolites used to synthesise plant biomass from CO2 and H2O
what does primary production provide?
energy source and substrates for major food chains
over a year what happens to the GPP?
1/2 fixed into biomass
1/2 lost by respiratory processes
what is net primary production (NPP)? (2 equations)
= GPP - autotrophic respiration
( often measured by difference in biomass sampled 1 year apart)
= photosynthetic biomass X growth efficiency X light
what is net ecosystem production (NEP)?
= NPP - heterotrophic respiration
what is net biome production (NBP)?
= NEP - losses through disturbance
how do you work out biomass?
= total ( NPP - losses through litter fall)
why may NPP not be estimated for correctly?
- some biomass is lost as dead litter fall
- may miss unaccounted losses of new biomass
- sampling errors
what is day photosynthetic CO2 uptake balanced by?
night CO2 release by respiration
what is photosynthetic biomass made up of?
green leaves/chlorophyll
what is growth efficiency a measure of?
of conversion of solar radiation to carbon units of NPP
what can quantify critical components of NPP model?
measurements by satellites of reflected radiation from earths surface
what is used to help you calculate amount of photosynthetically active radiation?
reflected radiation at different wavebands
how is density of leaves calculated?
measurements of reflected radiation in infra red/ red zone
how is phytoplankton chlorophyll and biomass in oceans calculated?
different wavebands of reflected blue light
what are the 2 roughly equal biospheres?
terrestrial and oceanic
where is there high NPP?
- where coastal upwelling of nutrients
- rainforests
which nutrients result in low productivity for deep oceans?
nitrogen, iron, phosphate
what may reduce NPP?
seasonal variations of temp or precipitation
for each 1c decrease in mean annual temp in Europe what is the effect on NPP?
reduced by 4%
a) NPP of pacific = ….
b) NPP of S and arctic oceans = ……
a) = NPP tropical rainforests
b) = NPP boreal forset
why is there more loss of C on and and what % of human emissions does this account for?
due to soil erosion and fires
20-30%
