Primary Productivity Flashcards
what is primary productivity?
the rate at which solar energy (sunlight) is converted into organic compounds (sugars like glucose or cellulose) via photosynthesis over a unit of time
the rate of photosynthesis of all producers in an area over a given period of time
what is gross primary productivity?
the total rate of photosynthesis in a given area
the total amount of sun energy (light) that plants capture and convert to energy (glucose) through photosynthesis
(the total amount of the paycheck)
what is net primary productivity?
the rate of energy storage by photosynthesizers in a given area, after subtracting the energy lost to respiration
the amount of energy (stored as biomass) leftover for consumers after plants have used some for respiration, aka amount of plant growth that takes place
(the take home pay, the amount of paycheck after taxes)
how is productivity measured?
units of energy per unit area per unit time (kcal/m^2/yr)
where is red light absorbed in water?
most red light is absorbed in the upper 1m of water
where is blue light absorbed in water?
blue light only penetrates deeper than 100m in the clearest water
how does the penetration of light in water affect photosynthesizers in aquatic ecosystems?
since blue light can’t penetrate water very far unless it’s super clear and most red light can barely penetrate past the first meter of water, photosynthesizers in aquatic ecosystems have adapted mechanisms to address the lack of visible light
since photosynthesis leads to plant growth, primary productivity can also be considered:
the amount of plant growth in an area over a given period of time
a high primary productivity means there is:
high plant growth and lots of food and shelter for animals
ecosystems with high primary productivity are usually more:
biodiverse (more diversity of species because can support more species) than ecosystems with low primary productivity
what is respiration loss?
plants use up some of the energy they generate via photosynethesis by doing cellular respiration which fuels movement and internal transportation
(the taxes taken out of a paycheck)
what is gross primary productivity?
the total amount of sun energy (light) that plants capture and convert to energy (glucose) through photosynthesis
the total paycheck amount
what is the equation for net primary productivity?
NPP = GPP - RL
net primary productivity is equal to gross primary productivity minus respiration loss
what is ecological efficiency?
the portion of incoming solar energy that is captured by plants and converted into biomass (NPP or food for consumers)
what is the typical ecological efficiency of an ecosystem?
generally, only 1% of all incoming sunlight is captured and converted into GPP via photosynthesis and the other 99% is either reflected back off the surface of the plant or passes through the leaf without being captured
of the captured 1%, only about 40% is converted into biomass/plant growth (NPP)
this means that 0.4% of total incoming solar energy goes to NPP
