How Primary Production Differs Across Ecosystems Flashcards
What is primary production?
The fixation of energy by autotrophs in an ecosystem
What is the biggest source of primary production?
Photosynthesis by plants, phytoplankton, and cyanobacteria
How is primary production expressed?
As weight of carbon per area
What is primary productivity?
Amount of energy fixed by autotrophs over an interval of time (rate)
What is the primary productivity of photosynthesis?
The rate at which plants fix carbohydrates using energy from the sun
What is gross primary production?
The total amount of energy fixed by all the autotrophs in the ecosystem
GPP = photosynthesis
What is net primary production?
The total amount of energy fixed by all the autotrophs in the ecosystem, minus energy loss
NPP = photosynthesis - respiration
What is net primary production?
The total amount of energy fixed by all the autotrophs in the ecosystem, minus energy loss
NPP = photosynthesis - respiration
What is remote sensing?
Science of acquiring information about the Earth’s surface without being in contact with it
Sensing and recording of reflected energy
We use cameras and sensors attached to satellites
What can remote sensing by satellites quantify?
The change in primary production on Earth
What is terrestrial net primary production limited by?
Temperature
Moisture
Precipitation
Actual evapotranspiration
Soil nutrients
What is actual evapotranspiration?
The total amount of water that evaporates and transpires off a landscape during a given time period measured in mm water/time
Measure that accounts for both temperature and precipitation as AET is affected by both
What relationship does actual evapotranspiration have with NPP?
Positive
What does adding nutrients to the soil do to NPP?
increase it
What is Liebig’s law of the minimum?
Plant growth is not limited by the total amount of all soil nutrients available but by the soil nutrient variable that is present in the lowest quantity
Why is growth not always the same with nutrient addition?
Some species have a high nutrient efficiency and grow best under low nutrients and are outcompeted when nutrients are high
At higher organizational level of ecosystems, nutrient addition increase NPP
What is aquatic net primary productivity limited by?
Nutrient availability
Where is marine NPP usually the greatest?
Near the shores of the oceans, where shores are where nutrients from terrestrial runoff arrive, nutrients arise from disturbance of bottom sediments, nutrient upwellings arrive from the greater water depths
What is eutrophication?
Nutrient enrichment of a water body through natural processes or pollution, generally causes rapid algal growth and reduces dissolved oxygen levels
What is hypoxia?
When water oxygen concentration is <2 mg O2 L^-1
What does eutrophication cause in marine ecosystems?
Hypoxia
What are dead zones?
Hypoxic areas in aquatic ecosystems, typically a consequence of pollution, eutrophication and high rates of decomposition, that are essentially devoid of life
