How Primary Production Differs Across Ecosystems

Question 1

What is primary production?

Answer 1

The fixation of energy by autotrophs in an ecosystem

Question 2

What is the biggest source of primary production?

Answer 2

Photosynthesis by plants, phytoplankton, and cyanobacteria

Question 3

How is primary production expressed?

Answer 3

As weight of carbon per area

Question 4

What is primary productivity?

Answer 4

Amount of energy fixed by autotrophs over an interval of time (rate)

Question 5

What is the primary productivity of photosynthesis?

Answer 5

The rate at which plants fix carbohydrates using energy from the sun

Question 6

What is gross primary production?

Answer 6

The total amount of energy fixed by all the autotrophs in the ecosystem

GPP = photosynthesis

Question 7

What is net primary production?

Answer 7

The total amount of energy fixed by all the autotrophs in the ecosystem, minus energy loss

NPP = photosynthesis - respiration

Question 8

What is net primary production?

Answer 8

The total amount of energy fixed by all the autotrophs in the ecosystem, minus energy loss

NPP = photosynthesis - respiration

Question 9

What is remote sensing?

Answer 9

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

Question 10

What can remote sensing by satellites quantify?

Answer 10

The change in primary production on Earth

Question 11

What is terrestrial net primary production limited by?

Answer 11

Temperature
Moisture
Precipitation
Actual evapotranspiration
Soil nutrients

Question 12

What is actual evapotranspiration?

Answer 12

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

Question 13

What relationship does actual evapotranspiration have with NPP?

Answer 13

Positive

Question 14

What does adding nutrients to the soil do to NPP?

Answer 14

increase it

Question 15

What is Liebig’s law of the minimum?

Answer 15

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

Question 16

Why is growth not always the same with nutrient addition?

Answer 16

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

Question 17

What is aquatic net primary productivity limited by?

Answer 17

Nutrient availability

Question 18

Where is marine NPP usually the greatest?

Answer 18

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

Question 19

What is eutrophication?

Answer 19

Nutrient enrichment of a water body through natural processes or pollution, generally causes rapid algal growth and reduces dissolved oxygen levels

Question 20

What is hypoxia?

Answer 20

When water oxygen concentration is <2 mg O2 L^-1

Question 21

What does eutrophication cause in marine ecosystems?

Answer 21

Hypoxia

Question 22

What are dead zones?

Answer 22

Hypoxic areas in aquatic ecosystems, typically a consequence of pollution, eutrophication and high rates of decomposition, that are essentially devoid of life