Net ecosystem production (NEP) in

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

limnology Limnology ( ; from Greek λίμνη, ''limne'', "lake" and λόγος, ''logos'', "knowledge") is the study of inland aquatic ecosystems. The study of limnology includes aspects of the biological, chemical, physical, and geological characteristi ...

, and

oceanography Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...

, is the difference between

gross primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...

(GPP) and net ecosystem respiration. Net ecosystem production represents all the carbon produced by plants in water through

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

that does not get respired by animals, other heterotrophs, or the plants themselves.

Overview

Net ecosystem production describes the total

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

in an

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

that can be stored, exported, or

oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

back into carbon dioxide gas. NEP is written in units of mass of carbon per unit area per time, for example, grams carbon per square meter per year (g C m⁻² yr⁻¹). In a given ecosystem, carbon quantified as net ecosystem production can eventually end up: oxidized by

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products. At a certain point in the combustion reaction, called the ignition ...

or ultraviolet radiation, accumulated as

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

, exported as organic carbon to another system, or accumulated in

sediments Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...

or soils. Carbon classified as NEP can be in the form of particles in the

particulate organic carbon Particulate organic matter (POM) is a fraction of total organic matter operationally defined as that which does not pass through a filter pore size that typically ranges in size from 0.053 to 2 millimeters. Particulate organic carbon (POC) is ...

(POC) pool such as

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

cells Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

(living) and

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

(non-living), or it can be in the form of dissolved substances that have not yet been decomposed in the dissolved organic carbon (DOC) pool. In any form, if the carbon gets respired or decomposed by any living organism (plant, animal,

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, or other microscopic organism) to release

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

, that carbon no longer counts as NEP. *NEP = GPP - respiration

y plants Y, or y, is the twenty-fifth and penultimate Letter (alphabet), letter of the Latin alphabet, used in the English alphabet, modern English alphabet, the alphabets of other western European languages and others worldwide. According to some auth ...

- respiration y animals and other heterotrophs

Net ecosystem production vs. net primary production

Net ecosystem production is all the carbon not respired, including respiration by plants ''and'' heterotrophic organisms such as animals and microbes. In contrast, net primary production (NPP) is all the carbon taken up by plants ( autotrophs) minus the carbon that the plants themselves respire through cellular respiration. *NPP = GPP - respiration

Net community production

Net community production (NCP) is the difference between net primary production and respiration by animals and heterotrophs only. Net community production is equal to net ecosystem production, and is only calculated differently. *NCP = NPP - respiration y animals and other heterotrophs Annual net community production (ANCP) is this carbon pool estimated per year. For example, annual net community production in the

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

South Pacific Ocean can be very close to zero, meaning that basically all carbon produced is respired by heterotrophs. In the rest of the Pacific Ocean, annual net community production can range from 2.0 to 2.4 mol C m⁻² yr⁻¹, meaning that carbon produced by phytoplankton (minus what the phytoplankton respire themselves) is greater during a given year than what gets respired by heterotrophs

References

{{reflist Plants Ecology Biological oceanography Marine biology Limnology

Overview

Net ecosystem production vs. net primary production

Net community production

See also

References