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21 Cards in this Set

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  • Back
Net primary proudction and net ecosystem production?
Estimates of how much energy or biomass an ecosystem is capturing or storing
Controls on land for NPP?
1. Temperature
2. Precipitation
3. Nutrient Availability
Controls in water for NPP?
1. Nutrient Availablity-e.g. Iron is an important micronutrient that limits marine productivity
Going up trophic levels?
There is less energy available
Food web dynamics?
can influence NPP
Other influences of NEP?
Humans and disturbances
Why care about ecosystem production?
1. Production represents the amount of energy available for all consumers (Like us).
2. Production represents C that is taken out of the atmospheric pool (CO2)
Overview of Production and its components?
Remember-Energy flows while matter cycles
1. Producers
Capture light energy into chemical bonds C now reduced to glucose and other forms
2. Herbivores
(aka primary consumer)
Use energy from those chemical bonds to build biomass and use energy for life. Carbon is sued in many structures.
3. Carnivores
(aka secondary consumers)
4. Detritivores
Consume Detritus
5. Detritus
Dead organic matter
(still energy in those bonds!)
Primary production?
The proces whereby plants, algae, and some bacteria (primary producers) capture the energy of light and transform it into the energy of chemical bonds in carbohydrate
1. Its rate is referred toa s primary productivity
2. 6CO2 + 6H2O  C6H12O6 + 6O2
3. For each g of C assimilated, 39kJ energy stored
The net amount of energy or biomass fixed by autotrophs (total photosynthesis minus all respiration)
Components of primary production?
Ther ate of primary production determines the rate of energy supply to the rest of the ecosystem:
GPP=total energy assimilated by primary producers
NPP=energy accumulated (in stored form) by primary producers
Gross - Net=respiration, the energy consumed by producers for maintenance and biosynthesis
Measuring primary production?
How much energy has been accumulated by net production?
1. Harvest techniques determine dry mass accumulated (net production)
2. Gas exchange techniques determine net uptake of CO2 in light (net production), production of CO2 in dark (respiration) and gross production as their sum
3. Radioactive carbon (14C) may also determine net uptake of carbon by plants
4. Remote sensing of "greenness" - NDVI
Problems of and alternatives for aquatic systems ?
1. Harvest approach is not practical for small organisms such as phytoplankton
2. Carbon is too abundant for practical measurement of small changes
1. Light and dark bottles may be used to determine chagnes in O2
2. 14C approach may also be used in unproductive waters
What controls NPP?
precipitation and temperature
Climatic controls?
Estimated actual evapotranspiration
What limits productivity in oceans where nutrients are already high?
1. Iron!
2. Experiments in flasks show that high nutrients don't lead to high algal production
3. Additions of iron do increase algal production if there are enough nutrients
4. Real experiments in the open ocean show the same thing (You can do BIG experiments)
5. Can we soak up greenhouse CO2 this way?
Where does all that production go?
All carbon is recycled to CO2 which can be re-used!
Net Ecosystem Production (NEP)?
Tehr ate of change of ALL biomass in the ecosystem:
NEP=GPP-Respiration total-Flux lateral
1. Net Primary production is how much the plants/autotrophs grow *NOTE* Annually it is always positive
2. NEP is how much the total biomass in teh ecosystem changes *NOTE* this can be positive, negative, or neutral
3. NPP can be very, very large when NEP is 0
What happens if you cut down a forest?
1. NPP goes way down because you killed most of the plants--They do recover but grow back slowly
2. NEP goes NEGATIVE because there is so much respiration
Why is NEP important?
It's the net ecosystem carbon accumulation or loss which is how much C is released or taken up fromt eh atmosphere