Primary Production: The Foundation of Ecosystems

A set of 100 vocabulary-style flashcards covering the concepts, components, measurements, and global patterns of primary production based on Chapter 2 of Fundamentals of Ecosystem Science.

Primary production

The storage of energy through the formation of organic matter from inorganic carbon compounds.

Autotrophic

Derived from the Greek words "autos" (self) and "trophikos" (pertaining to food); refers to organisms that are "self-feeders."

Photosynthesis

The incorporation of carbon dioxide into organic matter using energy from sunlight.

Ecosystem carbon cycle

A process that begins with the fixation of carbon, which is the incorporation of $CO_2$ into organic matter.

Fixation

The process of incorporating inorganic $CO_2$ into organic matter.

Biomolecules

Essential components such as proteins and nucleic acids built using nutrients like nitrogen and phosphorus.

Global carbon cycle

The broad cycle where primary production and the fate of fixed carbon influence atmospheric carbon dioxide concentrations.

Cryptic production

Primary production that is difficult to observe because loss processes, such as grazing, occur as rapidly as biomass accumulation.

Blooms

Conspicuous accumulations of phytoplankton scums that occur when growth rates consistently exceed loss rates.

Yield

The absolute amount of plant material produced in an ecosystem, often measured as mass per unit area or volume.

Biomass

The amount of primary producer material expressed as mass per area or volume, independent of time.

Gross primary production (GPP)

The total amount of carbon dioxide fixed into organic matter irrespective of any respiratory losses.

Net primary production (NPP)

The difference between gross primary production and autotrophic respiration ($R_a$); defined as $NPP = GPP - R_a$.

Autotrophic respiration ($R_a$)

The respiration performed by primary producers to support their own metabolism, growth, and reproduction.

Heterotrophic respiration ($R_h$)

Respiration performed by heterotrophic organisms, including consumers and decomposers.

Ecosystem respiration ($R_e$)

The sum of autotrophic respiration ($R_a$) and heterotrophic respiration ($R_h$).

Net ecosystem production (NEP)

The difference between gross primary production and ecosystem respiration, expressed as $NEP = GPP - R_e$.

Heterotrophic ecosystems

Ecosystems where $R_e > GPP$, resulting in a negative NEP, often subsidized by outside carbon imports.

Autotrophic ecosystems

Ecosystems with a positive NEP, meaning they produce more carbon than they respire internally.

$$dC_{org}$$

The rate of organic carbon accumulation in an ecosystem.

Carbon balance equation

$dC_{org} = NEP + I + CM - Ex - Ox_{nb}$.

$I$ (carbon budget)

Imported organic carbon that has not been respired.

$CM$ (carbon budget)

Net consumer movement into or out of an ecosystem.

$Ex$ (carbon budget)

Exported organic carbon from an ecosystem.

$$Ox_{nb}$$

Nonbiological oxidation of organic carbon, such as through fire or photo-oxidation.

Anoxic carbon fixation

A process where microorganisms fix carbon using hydrogen sulfide ($H_2S$) instead of water, producing sulfur.

Chemosynthesis

The process of oxidizing inorganic molecules to produce energy used to fix $CO_2$ into organic matter.

Nitrifying bacteria

Chemosynthetic bacteria that convert ammonia to nitrite or nitrite to nitrate to derive energy.

Methane-oxidizing bacteria

Microbes that grow at aerobic-anaerobic interfaces and exploit methane as an energy source.

Formaldehyde ($HCHO$)

The initial organic compound produced by methane-oxidizing bacteria during carbon fixation.

Anaerobic methane oxidation reaction

$5CH_4 + 8NO^{-}_3 + 8H^{+} \rightarrow 5CO_2 + 4H_2 + 14H_2O$.

Thermal vent regions

Deep-sea ecosystems where primary production is entirely powered by the chemosynthetic oxidation of sulfides and reduced compounds.

$^{14}C$ method

A sensitive aquatic technique measuring the uptake of radioactive inorganic carbon to estimate production between GPP and NPP.

Free water oxygen method

An aquatic measurement technique using in-situ sensors to track dissolved oxygen changes for estimating GPP, $R_e$, and NEP.

Oxygen dynamics equation

$\triangle O_2 = GPP - R_e + D$, where $D$ is diffusion across the air-water interface.

Allometric equations

Mathematical relationships used to quantify the correlation between tree diameter and woody biomass.

Lidar

A remote sensing technology using reflections of pulsed laser light to estimate forest biomass structure.

ANPP

Above-ground net primary production.

Mycorrhizae

Fungal symbionts associated with terrestrial plant roots that can constitute $10\%$ to $40\%$ of NPP in temperate forests.

Eddy covariance

A tower-based method measuring high-frequency $CO_2$ concentrations and wind speed to estimate exchange between a canopy and the atmosphere.

Net ecosystem exchange (NEE)

The difference between $CO_2$ efflux and influx measured by eddy covariance; negative values indicate net flux into the canopy.

Light attenuation

The rapid decrease of light intensity with depth in water or within terrestrial leaf canopies.

Saturating function

A mathematical relationship describing how primary production increases with light flux until it reaches a maximum.

$\alpha$ (Initial slope)

The parameter in the light-production model representing the initial rate of increase in production as light increases.

$$P^b_{max}$$

The parameter in the light-production model representing the maximum rate of photosynthesis.

Justus von Liebig

The German scientist who proposed in 1840 that a single factor limits production in any given ecosystem.

Macronutrients

Elements that constitute greater than $0.1\%$ of an organism's wet weight, including $C, N, H, O, P, S, K, Mg, Na$, and $Ca$.

Micronutrients

Trace elements like $Fe, Mn, Zn, Cu, B, Mo, Cl, V$, and $Co$ used mainly as enzyme cofactors.

Ecological stoichiometry

The study of the ratio of elements, specifically the balance of $C, N$, and $P$ within organisms.

Mean foliar $C:N$ ratio

A molar ratio of approximately $36$ observed in terrestrial plant leaves.

Mean foliar $C:P$ ratio

A molar ratio of approximately $970$ observed in terrestrial plant leaves.

Marine seston $C:N$ ratio

A molar ratio of approximately $7.7$ found in ocean particulate matter.

Marine seston $C:P$ ratio

A molar ratio of approximately $143$ found in ocean particulate matter.

Freshwater seston $C:N$ ratio

A molar ratio of approximately $30$ found in lake and river particulate matter.

Freshwater seston $C:P$ ratio

A molar ratio of approximately $307$ found in lake and river particulate matter.

Seston

Particulate matter collected on filters from water samples, representing a mixture of phytoplankton, other organisms, and detritus.

Colimitation

A state where multiple nutrients (such as $N, P$, and $Fe$) simultaneously regulate primary production.

Facilitated uptake

A process where one nutrient, like iron ($Fe$), assists in the uptake of another nutrient, like nitrate.

Herbivore regeneration

The stimulation of photosynthesis through the excretion or egestion of limiting nutrients by grazing animals.

Selective foraging

The process by which herbivores indirectly influence NPP by changing plant species composition.

Terrestrial herbivory rate

A general pattern where herbivores consume less than $10\%$ of primary production.

Algal-based aquatic herbivory rate

A pattern where herbivores often consume more than $50\%$ of net primary production.

Productivity of tropical forests

Ecosystems with high rates of production exceeding $700\,g\,C\,m^{-2}\,y^{-1}$.

Global marine NPP

Estimated to be approximately $52\,Pg\,C\,y^{-1}$.

Global terrestrial NPP

Estimated to be approximately $54\,Pg\,C\,y^{-1}$.

Global gross primary production

Estimated at $\approx 120-130\,Pg\,C\,y^{-1}$ for both terrestrial and marine environments.

Detritus

Dead organic matter; the fate of up to $90\%$ of NPP in forest ecosystems.

Refractory organic matter

Organic carbon that is hard to decompose and accumulates over long periods in soils and sediments.

Dissolved organic carbon (DOC)

Soluble organic matter that can be exported from terrestrial systems into aquatic systems.

DOC export rates

A range of $0.4$ to $8.3\,g\,C\,m^{-2}\,y^{-1}$ for the 30 largest rivers in the world.

Photo-oxidation

The abiotic oxidation of organic carbon back to $CO_2$ by exposure to ultraviolet light.

Physiological ecologist scale

Research focusing on net photosynthesis of individual leaves within chambers.

Micrometeorologist scale

Research focusing on the NEE of an entire forest using eddy covariance.

Plant ecologist scale

Research focusing on NPP via litterfall baskets and woody biomass accumulation measurements.

Geologist scale

Research focusing on ancient primary production sequestered in reservoirs like coal seams.

Toolik Lake (Dry tundra) NPP

$65\,g\,C\,m^{-2}\,y^{-1}$.

Curlew Valley (Shrubland) NPP

$110\,g\,C\,m^{-2}\,y^{-1}$.

Toolik Lake (Wet tundra) NPP

$120\,g\,C\,m^{-2}\,y^{-1}$.

Schefferville (Boreal woodland) NPP

$170\,g\,C\,m^{-2}\,y^{-1}$.

Central Plains (Short grassland) NPP

$200\,g\,C\,m^{-2}\,y^{-1}$.

Osage Prairie (Tall grassland) NPP

$425\,g\,C\,m^{-2}\,y^{-1}$.

Harvard Forest (Temperate deciduous) NPP

$650\,g\,C\,m^{-2}\,y^{-1}$.

Ducke Forest (Tropical evergreen) NPP

$1050\,g\,C\,m^{-2}\,y^{-1}$.

Hudson River NPP

$55\,g\,C\,m^{-2}\,y^{-1}$.

Mirror Lake NPP

$65\,g\,C\,m^{-2}\,y^{-1}$.

Walker Branch (Stream) NPP

$150\,g\,C\,m^{-2}\,y^{-1}$.

Pacific Ocean (North of Hawaii) NPP

$185\,g\,C\,m^{-2}\,y^{-1}$.

Lake Mendota (Eutrophic) NPP

$345\,g\,C\,m^{-2}\,y^{-1}$.

Cap Blanc (Oceanic upwelling) NPP

$730\,g\,C\,m^{-2}\,y^{-1}$.

Off Southern California (Kelp forest) NPP

$730\,g\,C\,m^{-2}\,y^{-1}$.

Duplin River (Salt marsh estuary) NPP

$760\,g\,C\,m^{-2}\,y^{-1}$.

Coral reef NPP

Values estimated at $> 1000\,g\,C\,m^{-2}\,y^{-1}$.

Masting

Episodic seed production (e.g., in oak trees) that makes NPP difficult to measure accurately.

$$Pg\,C\,y^{-1}$$

Petagrams of carbon per year; the units used for global-scale primary production estimates.

Carbon sequestration

The long-term storage of fixed primary production in reservoirs like soil or woody biomass.

Yellowstone National Park grazing

A case where elk and bison graze $45\%$ of the annual primary production.

Algae

Autotrophic microbes that conduct photosynthesis, common in aquatic ecosystems.

Trophikos

The Greek word meaning "pertaining to food," from which the term autotroph is partially derived.

Ecosystem sinks

Systems that result in the net removal of $CO_2$ from the atmosphere through biological storage.

Methane oxidation energy

Energy generated by the reducing power of hydrogen ions and electrons, used to fix inorganic carbon.