6.3b how does photosynthesis regulate the atmospheric composition

what does more photosynthesis mean

less carbon in atmosphere

photosynthesis equation

CO2 + H2O -> C6H12O6 + O2

where is CO2 stored

in organi matter buried in soil

what happens without carbon

nutrients and water cycles cannot operate properly

what does soil health depend on

amount of organic carbon in soil, depends on inputs (e.g. plants) and outputs (e.g. decomposition)

what happens if plant residue is added to soil at faster rate than organisms convert to CO2

carbon will be removed from atmosphere and sequestered in soil

what is net primary productivity (NPP)

measure biomass gained by plants, represents storage of carbon in ecosystem

what is the order in productivity of biomes starting with most productive

tropical rainforest, savannah and tropical grasslands, temperate forest, temperate grassland, boreal forest (taiga), deserts and dry shrub land, tundra

where is most carbon stored in the tropical rainforest

above ground biomass

where is most carbon stored in the savannah and tropical grasslands

soil

where is most carbon stored in the temperate forest

biomass above and underground (roots)

where is most carbon stored in the temperate grasslands

soil

where is most carbon stored in the boreal forest (taiga)

soil

where is most carbon stored in the deserts and dry shrub land

soil

where is most carbon stored in the tundra

permafrost

what are the main threats for the tropical rainforest

deforestation for logging, agriculture, minerals and hydro electric power (HEP)

what are the main threats for the savannah and tropical grasslands

fire followed by conversion to pasture/crops

what are the main threats for the temperate forest

historic losses but now mainly ceased

what are the main threats for the temperate grasslands

degradation by livestock and crops 

what are the main threats for the boreal forest (taiga)

fires, logging, mining

what are the main threats for the deserts and dry shrub land

fire

what are the main threats for the tundra

rising temps

what is the NPP PgC/yr for tropical rainforests

16-23

what is the NPP PgC/yr for savannah and tropical grasslands

15-19

what is the NPP PgC/yr for temperate forest

4.6-9

what is the NPP PgC/yr for temperate grasslands

3.4-7

what is the NPP PgC/yr for boreal forest (taiga)

2.6-4.6

what is the NPP PgC/yr for deserts and dry shrub land

0.5-3.5

what is the NPP PgC/yr for tundra

0.5-1

what is a positive feedback loop

bad, large scale disruptions to system leading to tipping point with new balance

what is negative feedback loop

good, small scale disruptions are balanced or cancelled out

what is the positive feedback loop for permafrost 

global warming melts permafrost causing decomposition of plant material in wet soil, released CO2 and CH4, increasing global warming

what is the negative feedback loop for permafrost

high CO2 in atmosphere causes global warming leading to melting permafrost allowing shrubs and trees to grow where they couldn’t previously, increasing photosynthesis and reducing atmospheric CO2

does melting permafrost increase or decrease atmospheric carbon and why

increase as carbon stored in frozen soil released into atmosphere

does algal blooms increase or decrease atmospheric carbon and why

decrease as photosynthesis in pants taking in carbon from atmosphere

does shorter winters due to climate change increase or decrease atmospheric carbon and why

decrease as more plant growth taking in CO2

does arctic sea ice melting increase or decrease atmospheric carbon and why

decrease as more photosynthesis as more plants in sea

does increased desertification increase or decrease atmospheric carbon and why

increase as less CO2 in soil as its eroded and less vegetation

does burning of amazon rainforest increase or decrease atmospheric carbon and why

increase as trees release the carbon

does reduced snow cover in tundra increase or decrease atmospheric carbon and why

decrease as more plants can survive so more photosynthesis

does coral reef bleaching increase or decrease atmospheric carbon and why

increase as less coral so less photosynthesis 

does warming arctic increase or decrease atmospheric carbon and why

decrease as more decomposition in soil releases carbon and more plant growth

does burning fossil fuels increase or decrease atmospheric carbon and why

increase as carbon is released in combustion