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%
what can a ‘biological pump’ maintain?
high conc of dissolved C in ocean
what part of the ocean has high solubility?
cold waters at high latitudes
dense water sinks removing CO2 to depths
in the ocean what is 1% of it and what is the other 99%?
1%: inorganic C
99%: bicarbonate and carbonate ions
fill in the equation:
CO2 + H2O + ___ —> _____
CO3^2-
2HCO3-
what is the decreases in NPP by biological pump correlated with?
increase in sea surface temp
what decreases the effectiveness of solubility pump?
decreased carbonate ion conc and decreased ph
C accumulation in atmosphere: atmospheric CO2 conc: global warming
number comparison?
200: 100: 1
what was discussed to reduce C emissions?
planting trees
what could total deforestation lead to a global warming of?
2c
on what scale can global climate change for the better?
internationally
what % of anthropogenic emissions do oceanic and terrestrial sinks sequester?
60%
what can increasing iron stimulate?
plantkon growth and C uptake
what could terrestrial NPP be harvested to manufacture?
ethanol from sugar cane rather than using petrol
why does use of sugar cane have a neutral effect of atmospheric CO2?
grows and sequesters C but C is releases again in car exhaust
why is ethanol from sugar cane not C neutral?
costs for growing and harvesting it
what % of energy content of petrol does sugar cane have?
65%
what is likely to happen to natural sinks for CO2 emissions?
slow
what would converting UK land for ethanol production impact?
area for food crops, species diversity, natural vegetation
what does reduced primary production of terrestrial biosphere result in?
warmer and drier conditions- drought more likely
warming oceans leads to stratification what does this lead to?
reduced nutrient supply for phytoplankton and reduced solubility of CO2 in warm waters so decreased primary production
what should be done to improve emission rates/climate change?
reduce emissions from CO2 sources and move away from energy systems based on carbon
