Global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. As an estimate of autotroph biomass, it is only a rough indicator of primary production potential, and not an actual estimate of it. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE.

Primary production is the production of organic compounds from atmospheric or aquatic carbon dioxide, principally through the process of photosynthesis, with chemosynthesis being much less important. All life on earth is directly or indirectly reliant on primary production. The organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain. In terrestrial ecoregions, these are mainly plants, while in aquatic ecoregions algae are primarily responsible. Primary production is distinguished as either net or gross, the former accounting for losses to processes such as cellular respiration, the latter not. Image File history File links SeaWiFS Global Biosphere September 1997 - August 1998 This composite image gives an indication of the magnitude and distribution of global primary production, both oceanic (mg/m3 chlorophyll a) and terrestrial (normalized difference land vegetation index). ... Image File history File links SeaWiFS Global Biosphere September 1997 - August 1998 This composite image gives an indication of the magnitude and distribution of global primary production, both oceanic (mg/m3 chlorophyll a) and terrestrial (normalized difference land vegetation index). ... For the band, see 1997 (band). ... Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ... SeaWiFS stands for Sea-viewing Wide Field-of-view Sensor. ... This article is about the American space agency. ... Aerial view of Goddard Space Flight Center. ... GeoEye is a space imaging firm based in Dulles, Virginia. ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... The leaf is the primary site of photosynthesis in plants. ... Chemosynthesis is the biological conversion of 1-carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e. ... Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph Flowchart to determine if a species is autotroph, heterotroph, or a subtype An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple inorganic molecules and an external source of energy... This article does not cite any references or sources. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... For other uses, see Plant (disambiguation). ... An ecoregion (ecological region), sometimes called a bioregion, is the next smallest ecologically and geographically defined area beneath realm or ecozone. Ecoregions cover relatively large area of land or water, and contain characteristic, geographically distinct assemblage of natural communities and species. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Cellular respiration was discovered by mad scientist Mr. ...

Overview

The Calvin cycle of photosynthesis

At the fundamental level, primary production is the conversion of energy in the form of electromagnetic radiation into stored chemical energy by living organisms. The main source of this energy is the sun. A minute fraction of primary production is driven by organisms utilising the chemical energy of inorganic molecules. Image File history File links Download high resolution version (856x742, 51 KB)This image was copied from wikipedia:en. ... Image File history File links Download high resolution version (856x742, 51 KB)This image was copied from wikipedia:en. ... Overview of the Calvin cycle and carbon fixation The Calvin cycle (or Calvin-Benson cycle or carbon fixation) is a series of biochemical reactions that takes place in the stroma of chloroplasts in photosynthetic organisms. ... Electromagnetic waves can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. ... In chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. ... “Life on Earth” redirects here. ... Sol redirects here. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ...

Regardless of its source, this energy is used to synthesise complex organic molecules from simpler inorganic compounds such as carbon dioxide (CO₂) and water (H₂O). The following two equations are simplified representations of photosynthesis (top) and (one form of) chemosynthesis (bottom) : An organic compound is any of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

CO₂ + H₂O + light CH₂O + O₂

CO₂ + O₂ + 4 H₂S CH₂O + 4 S + 3 H₂O

In both cases, the end point is reduced carbohydrate (CH₂O), typically molecules such as glucose or other sugars. These relatively simple molecules may be then used to synthesise further more complicated molecules, including proteins, complex carbohydrates, lipids, and nucleic acids, or be respired to perform work. Consumption of primary producers by heterotrophic organisms, such as animals, then transfers these organic molecules (and the energy stored within them) up the food chain, fueling all of the Earth's living systems. Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... Lactose is a disaccharide found in milk. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... This article is about sugar as food and as an important and widely-traded commodity. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Figure 1: Basic lipid structure. ... Highly simplified diagram of a double-stranded nucleic acid. ... Cellular respiration was discovered by mad scientist Mr. ... In thermodynamics, work is the quantity of energy transferred from one system to another without an accompanying transfer of entropy. ... Flowchart to determine if a species is autotroph, heterotroph, or a subtype A heterotroph (Greek heterone = (an)other and trophe = nutrition) is an organism that requires organic substrates to get its carbon for growth and development. ... For other uses, see Animal (disambiguation). ... This article does not cite any references or sources. ... This article is about Earth as a planet. ...

GPP and NPP

Gross primary production (GPP) is the total amount of energy fixed by primary producers in a given area or ecosystem. Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues. The remaining fixed energy is referred to as net primary production (NPP). Net primary production is the rate at which new biomass accrues in an ecosystem. Some net primary production will go towards growth and reproduction of primary producers, while some will be consumed by herbivores. Both gross and net primary production are in units of mass / area / time. In terrestrial ecosystems, the mass of carbon per unit area per year (g C/m²/yr) is most often used. Cellular respiration was discovered by mad scientist Mr. ...

Terrestrial production

An oak tree; a typical modern, terrestrial autotroph

On the land, almost all primary production is now performed by vascular plants, although a small fraction comes from algae and non-vascular plants such as mosses and liverworts. However, before the evolution of vascular plants, non-vascular plants played a more significant role. Primary production on land is a function of many factors, but principally local hydrology and temperature (the latter covaries to an extent with light, the source of energy for photosynthesis). While plants cover much of the Earth's surface, they are strongly curtailed wherever temperatures are too extreme or where necessary plant resources (principally water and light) are limiting, such as deserts or polar regions. Oak from Danish wiki da:Billede:Raunkiaer. ... Oak from Danish wiki da:Billede:Raunkiaer. ... Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus (from Latin oak tree), and some related genera, notably Cyclobalanopsis and Lithocarpus. ... Divisions Non-seed-bearing plants †Rhyniophyta †Zosterophyllophyta Lycopodiophyta †Trimerophytophyta Pteridophyta Ophioglossophyta Superdivision Spermatophyta †Pteridospermatophyta Pinophyta Cycadophyta Ginkgophyta Gnetophyta Magnoliophyta The vascular plants, tracheophytes or higher plants are plants in the kingdom Plantae that have specialized tissues for conducting water, minerals, and photosynthetic products through the plant. ... Divisions Simple nonvascular plants   Green algae Complex nonvascular plants   Bryophyta, mosses   Marchantiophyta, liverworts   Anthocerotophyta, hornworts Non-vascular plants is a general term for those plants (including the green algae) without a vascular system (xylem and phloem). ... For other uses, see Moss (disambiguation). ... Orders Jungermanniopsida Metzgeriales (simple thalloids) Haplomitriales (Calobryales) Jungermanniales (leafy liverworts) Marchantiopsida Sphaerocarpales (bottle liverworts) Marchantiales (complex thalloids) Monocleales Liverworts are a division of plants commonly called hepatics, Marchantiophyta or liverworts. ... This article is about evolution in biology. ... Graph of example function, The mathematical concept of a function expresses the intuitive idea of deterministic dependence between two quantities, one of which is viewed as primary (the independent variable, argument of the function, or its input) and the other as secondary (the value of the function, or output). A... Water covers 70% of the Earths surface. ... For other uses, see Temperature (disambiguation). ... This article is about arid terrain. ... Location of the polar regions Northern Hemisphere permafrost (permanently frozen ground) in purple. ...

Water is "consumed" in plants by the processes of photosynthesis (see above) and transpiration. The latter process (which is responsible for about 90% of water use) is driven by the evaporation of water from the leaves of plants. It allows plants to transport water and mineral nutrients from the soil to growth regions, and also cools a plant down. It can be regulated by structures known as stomata, but these also regulate the supply of carbon dioxide from the atmosphere, so that decreasing water loss also decreases carbon dioxide gain. Crassulacean acid metabolism (CAM) and C4 plants use physiological and anatomical workarounds to increase their water-use efficiency and allow increased primary production to take place under conditions that would limit "normal" C3 plants (the majority of plant species). Transpiration is the evaporation of excess water from aerial parts and of plants, especially leaves but also stems, flowers and fruits. ... “Vaporization” redirects here. ... Look up foliage in Wiktionary, the free dictionary. ... For other uses, see Mineral (disambiguation). ... A nutrient is either a chemical element or compound used in an organisms metabolism or physiology. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Technically, soil forms the pedosphere: the interface between the lithosphere (rocky part of the planet) and the biosphere, atmosphere, and hydrosphere. ... Stoma of a leaf under a microscope. ... Crassulacean Acid Metabolism (CAM) is a carbon fixation pathway in some photosynthetic plants. ... Overview of C4 carbon fixation C4 carbon fixation is one of three methods, along with C3 and CAM photosynthesis, used by land plants to fix carbon dioxide (binding the gaseous molecules to dissolved compounds inside the plant) for sugar production through photosynthesis. ... This article or section does not cite any references or sources. ... Human heart and lungs, from an older edition of Grays Anatomy. ... C3 carbon fixation is a pathway for carbon fixation in photosynthesis. ...

Oceanic production

Marine diatoms; an example of planktonic microalgae

In a reversal of the pattern on land, in the oceans, almost all primary production is performed by algae, with a small fraction contributed by vascular plants and other groups. Algae encompass a diverse range of organisms, ranging from single floating cells to attached seaweeds. They include photoautotrophs from a variety of groups: prokaryotic bacteria (both eubacteria and archaea); and three eukaryote categories the green, brown and red algae. Vascular plants are represented in the ocean by groups such as the seagrasses. Image File history File links Beautiful marine diatoms as seen through a microscope. ... Image File history File links Beautiful marine diatoms as seen through a microscope. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ... Divisions Non-seed-bearing plants Equisetophyta Lycopodiophyta Psilotophyta Pteridophyta Superdivision Spermatophyta Pinophyta Cycadophyta Ginkgophyta Gnetophyta Magnoliophyta The vascular plants are those plants that have specialized cells for conducting water and sap within their tissues, including the flowering plants, conifers and other gymnosperms, but not mosses, algae, and the like (nonvascular... Seaweed covered rocks in the UK Phycologists consider seaweed to refer any of a large number of marine benthic algae that are multicellular, macrothallic (large-bodied), and thus differentiated from most algae that tend towards microscopic size (Smith, 1944). ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Divisions Chlorophyta Charophyta Streptophytina (Subdivision) The green algae are the large group of algae from which the embryophytes (higher plants) emerged. ... Orders Ascoseirales Chordariales Cutleriales Desmarestiales Dictyosiphonales Dictyotales Ectocarpales Fucales Laminariales(kelps) Scytosiphonales Scytothamnales Sphacelariales Sporochnales Syringodermatales Tilopteridales The brown algae or phaeophytes are a large group of multicellular algae, including many notable seaweeds. ... Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae Red algae (Rhodophyta, pronounced /ˈrəʊdə(ʊ)ˌfʌɪtə/) are a large group of mostly multicellular, marine algae, including many notable seaweeds. ... Seagrass from the coast of Florida Sea grass (or sea-grass in British English) are flowering plants from four plant families (Posidoniaceae, Zosteraceae, Hydrocharitaceae, and Cymodoceaceae) that grow in the marine saline environment. ...

In another departure from the situation on land, the majority of primary production in the ocean is performed by microscopic organisms, the phytoplankton. Larger autotrophs, such as the seagrasses and macroalgal seaweeds are generally confined to the littoral zone and adjacent shallow waters, where they can attach to the underlying substrate but still be within the photic zone. There are exceptions, such as Sargassum, but the vast majority of free-floating production takes place within microscopic organisms. A cluster of Escherichia coli bacteria magnified 10,000 times. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada Dead Mans Fingers (Codium fragile) off Massachusetts coast For the band, see; Seaweed (band) For the rock musician, see; Seaweed (musician) Seaweeds are any of a large number of marine benthic algae. ... A littoral is the region near the shoreline of a body of fresh or salt water. ... A holdfast is a rootlike plant structure that anchors a seaweed. ... The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. ... Species Sargassum bacciferum, aka. ...

The factors limiting primary production in the ocean are also very different from those on land. The availability of water, obviously, is not an issue (though its salinity can be). Similarly, temperature, while affecting metabolic rates (see Q₁₀), ranges less widely in the ocean than on land because the heat capacity of seawater buffers temperature changes, and the formation of sea ice insulates it at lower temperatures. However, the availability of light, the source of energy for photosynthesis, and mineral nutrients, the building blocks for new growth, play crucial roles in regulating primary production in the ocean. Annual mean sea surface salinity for the World Ocean. ... A few of the metabolic pathways in a cell. ... The Q10 temperature coefficient The Q10 temperature coefficient is a measure of the rate of change of a system as a consequence of increasing the temperature by 10ºC. There are many examples where the Q10 is used, one being the calculation of the nerve conduction velocity and another being... To meet Wikipedias quality standards, this article or section may require cleanup. ... An icebreaker navigates through young (1 year old) sea ice Nilas Sea Ice in arctic Sea ice is formed from ocean water that freezes. ... Thermal insulation on the Huygens probe The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. ... Nutrients and the body A nutrient is any element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ...

Light

A kelp forest; an example of attached macroalgae

The sunlit zone of the ocean is called the photic zone (or euphotic zone). This is a relatively thin layer (10-100 m) near the ocean's surface where there is sufficient light for photosynthesis to occur. For practical purposes, the thickness of the photic zone is typically defined by the depth at which light reaches 1% of its surface value. Light is attenuated down the water column by its absorption or scattering by the water itself, and by dissolved or particulate material within it (including phytoplankton). Download high resolution version (1296x972, 528 KB)Kelp forest, Otago peninsular, Oct 2004 Author: User:Velela. ... Download high resolution version (1296x972, 528 KB)Kelp forest, Otago peninsular, Oct 2004 Author: User:Velela. ... Kelp Forest Kelp forests are a type of marine ecosystem established around colonies of kelp; they contain rich biodiversity. ... Seaweed-covered rocks in the UK Biologists, specifically marine biologists, consider seaweed to be any of a large number of marine benthic algae that are multicellular, macrothallic, and thus differentiated from most algae that tend to be microscopic in size [1]. Many phycologists prefer the term marine macroalgae over seaweeds... This article is about Physics. ... Absorption, in optics, is the process by which the energy of a photon is taken up by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels. ... Scattering is a general physical process whereby some forms of radiation, such as light, sound or moving particles, for example, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which it passes. ...

Net photosynthesis in the water column is determined by the interaction between the photic zone and the mixed layer. Turbulent mixing by wind energy at the ocean's surface homogenises the water column vertically until the turbulence dissipates (creating the aforementioned mixed layer). The deeper the mixed layer, the lower the average amount of light intercepted by phytoplankton within it. The mixed layer can vary from being shallower than the photic zone, to being much deeper than the photic zone. When it is much deeper than the photic zone, this results in phytoplankton spending too much time in the dark for net growth to occur. The maximum depth of the mixed layer in which net growth can occur is called the critical depth. As long as there are adequate nutrients available, net primary production occurs whenever the mixed layer is shallower than the critical depth. The oceanic or limnological mixed layer is the top zone in the ocean or a lake, having variable depth depending on how far the energy from the wind has penetrated into the water. ... In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. ... For other uses, see Wind (disambiguation). ... A wave that loses amplitude is said to dissipate. ...

Both the magnitude of wind mixing and the availability of light at the ocean's surface are affected across a range of space- and time-scales. The most characteristic of these is the seasonal cycle (caused by the consequences of the Earth's axial tilt), although wind magnitudes additionally have strong spatial components. Consequently, primary production in temperate regions such as the North Atlantic is highly seasonal, varying with both incident light at the water's surface (reduced in winter) and the degree of mixing (increased in winter). In tropical regions, such as the gyres in the middle of the major basins, light may only vary slightly across the year, and mixing may only occur episodically, such as during large storms or hurricanes. This article or section is in need of attention from an expert on the subject. ... Figure 1 This is a diagram of the seasons. ... In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... For other uses, see Wind (disambiguation). ... For the usage in virology, see temperate (virology). ... The Atlantic Ocean is Earths second-largest ocean, covering approximately one_fifth of its surface. ... A noontime scene from the Philippines on a day when the Sun is almost directly overhead. ... A gyre is any manner of swirling vortex. ... Diagrammatic cross-section of an ocean basin, showing the various geographic features. ... For other uses, see Storm (disambiguation). ... This article is about weather phenomena. ...

Nutrients

Annual mean sea surface nitrate for the World Ocean. Data from the World Ocean Atlas 2001.

Mixing also plays an important role in the limitation of primary production by nutrients. Inorganic nutrients, such as nitrate, phosphate and silicic acid are necessary for phytoplankton to synthesise their cells and cellular machinery. Because of gravitational sinking of particulate material (such as plankton, dead or faecal material), nutrients are constantly lost from the photic zone, and are only replenished by mixing or upwelling of deeper water. This is exacerbated where summertime solar heating and reduced winds increases vertical stratification and leads to a strong thermocline, since this makes it more difficult for wind mixing to entrain deeper water. Consequently, between mixing events, primary production (and the resulting processes that leads to sinking particulate material) constantly acts to consume nutrients in the mixed layer, and in many regions this leads to nutrient exhaustion and decreased mixed layer production in the summer (even in the presence of abundant light). However, as long as the photic zone is deep enough, primary production may continue below the mixed layer where light-limited growth rates mean that nutrients are often more abundant. Image File history File links Download high resolution version (1550x1075, 285 KB) Summary Annual mean sea surface nitrate from the World Ocean Atlas 2001. ... Image File history File links Download high resolution version (1550x1075, 285 KB) Summary Annual mean sea surface nitrate from the World Ocean Atlas 2001. ... The term World Ocean refers to the interconnected system of the planet Earths marine waters. ... The World Ocean Atlas (WOA) is a data product of the Ocean Climate Laboratory of the National Oceanographic Data Center (USA). ... Trinitrate redirects here. ... A phosphate, in inorganic chemistry, is a salt of phosphoric acid. ... Silicic acid is a general name for a family of chemical compounds of silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n. ... Synthesis (from the ancient Greek σύν (with) and θεσις (placing), is commonly understood to be an integration of two or more pre-existing elements which results in a new creation. ... Gravity is a force of attraction that acts between bodies that have mass. ... Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ... Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. ... The thermocline is a layer within a body of water where the temperature changes rapidly with depth. ...

Iron

Another factor relatively recently discovered to play a significant role in oceanic primary production is the micronutrient iron^[1]. This is used as a cofactor in enzymes involved in processes such as nitrate reduction and nitrogen fixation. A major source of iron to the oceans is dust from the Earth's deserts, picked up and delivered by the wind as eolian dust. In regions of the ocean that are distant from deserts or that are not reached by dust-carrying winds (for example, the Southern and North Pacific oceans), the lack of iron can severely limit the amount of primary production that can occur. These areas are sometimes known as HNLC (High-Nutrient, Low-Chlorophyll) regions, because the scarcity of iron both limits phytoplankton growth and leaves a surplus of other nutrients. Micronutrients for plants: There are about eight nutrients essential to plant growth and health that are only present in very small quantities. ... For other uses, see Iron (disambiguation). ... A cofactor is any substance that needs to be present in addition to an enzyme to catalyze a certain reaction. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Nitrate reducatse are group of enzymes which reduce nitrate to nitrite This article belongs in one or more categories. ... Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form (N2) in the atmosphere and converted into nitrogen compounds (such as, notably, ammonia, nitrate and nitrogen dioxide)[1] useful for other chemical processes. ... This article is about arid terrain. ... Eolian (or aeolian) processes pertain to the activity of the winds. ... The Southern Ocean, also known as the Antarctic Ocean or South Polar Ocean, is the oceanic division completely in Earths southern hemisphere encircling Antarctica, comprising the southernmost waters of the World Ocean south of 60° S latitude. ... For other meanings of Pacific, see Pacific (disambiguation). ... HNLC stands for high nitrate, low carbon - a term used in marine ecology to describe areas in the ocean where the phytoplankton development is low in spite of high nutrient contents, caused by the lack of iron. ...

Human impact and appropriation

Extensive human land use results in various levels of impact on actual NPP (NPP_act). In a few regions, such as the Nile valley, irrigation has resulted in a considerable increase in primary production. This is an exception to the rule, which is that there is a NPP reduction due to land changes (ΔNPP_LC) of 9.6% across global land-mass. In addition to this, end consumption by people raises the total human appropriation of net primary production (HANPP) to 23.8% of potential vegetation (NPP₀). This disproportionate amount reduces energy available to other species, having a marked impact on biodiversity, flows of carbon, water and energy, and ecosystem services.^[2] Land use is the pattern of construction and activity land is used for. ... The Nile (Arabic: , transliteration: , Ancient Egyptian iteru, Coptic piaro or phiaro) is a major north-flowing river in Africa, generally regarded as the longest river in the world. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ... Rainforests are among the most biodiverse ecosystems on earth Biodiversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. ... Humankind benefits from a multitude of resources and processes that are supplied by natural ecosystems. ...

Measurement

The methods for measurement of primary production vary depending on whether gross vs net production is the desired measure, and whether terrestrial or aquatic systems are the focus. Gross production is almost always harder to measure than net, because of respiration, which is a continuous and ongoing process that consumes some of the products of primary production (i.e. sugars) before they can be accurately measured. Also, terrestrial ecosystems are generally more difficult because a substantial proportion of total productivity is shunted to below-ground organs and tissues, where it is logistically difficult to measure. Shallow water aquatic systems can also face this problem.

Scale also greatly affects measurement techniques. While biochemically-based techniques are appropriate for plant tissues, organs, whole plants, or plankton samples, they are decidedly inappropriate for large scale terrestrial field situations. There, net primary production is almost always the desired variable, and estimation techniques involve various methods of estimating dry-weight biomass changes over time. Biomass estimates are often converted to an energy measure, such as kilocalories, by an empirically determined conversion factor. A central concept in science and the scientific method is that all evidence must be empirical, or empirically based, that is, dependent on evidence or consequences that are observable by the senses. ...

Terrestrial

In terrestrial ecosystems, researchers generally measure net primary production. A variety of field methods are used to estimate NPP. Although its definition is straightforward, field measurements used to estimate productivity vary according to investigator and biome. Field estimates rarely account for below ground productivity, herbivory, decomposition, turnover, litterfall, volatile organic compounds, root exudates, and allocation to symbiotic microorganisms. As discussed^{[3] [4]}, biomass based NPP estimates result in underestimation of NPP due to incomplete accounting of these components. However, many field measurements correlate well to NPP. Comprehensive reviews of field methods used to estimate NPP can be found^[3], ^[5]. “Spoilage” redirects here. ... Common Clownfish (Amphiprion ocellaris) in their Magnificent Sea Anemone (Heteractis magnifica) home. ...

The major unaccounted for pool is belowground productivity, especially production and turnover of roots. Belowground components of NPP are difficult to measure. BNPP is often estimated based on a ratio of ANPP:BNPP rather than direct measurements.

Grasslands: Most frequently, peak standing biomass is assumed to measure NPP. In systems with persistent standing litter, live biomass is commonly reported. Measures of peak biomass are more reliable in if the system is predominantly annuals, or when perennial, if there was a synchronous phenology driven by a strong seasonal climate. These methods may underestimate ANPP in grasslands by as much as 2 (temperate) to 4 (tropical) fold^[4]. Repeated measures of standing live and dead biomass provide more accurate estimates of all grasslands, particularly those with large turnover, rapid decomposition, and interspecific variation in timing of peak biomass. Wetland productivity, e.g.; of marshes and fens, is similarly measured. In Europe, annual mowing makes the annual biomass increment of wetlands evident. For the usage in virology, see temperate (virology). ... The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the two tropics: the Tropic of Cancer in the north and the Tropic of Capricorn in the southern hemisphere. ... A subtropical wetland in Florida, USA, with an endangered American Crocodile. ... For other uses, see Europe (disambiguation). ...

Forests: Methods used to measure forest productivity are more diverse than those of grasslands. Biomass increment based on stand specific allometry plus litterfall is considered a suitable although incomplete accounting of above-ground net primary production (ANPP)^[3]. Field measurements used as a proxy for ANPP include annual litterfall, diameter or basal area increment (DBH or BAI), and volume increment. Allometry is the science studying the differential growth rates of the parts of a living organisms body part or process. ... Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk of a tree. ...

Aquatic

In aquatic systems, primary production is typically measured using one of three main techniques ^[6]:

1. variations in oxygen concentration within a sealed bottle (developed by Gaarder and Gran in 1927)
2. incorporation of inorganic carbon-14 (in the form of sodium bicarbonate) into organic matter ^{[7] [8]}
3. fluorescence kinetics (technique still a research topic)

The technique developed by Gaarder and Gran uses variations in the concentration of oxygen under different experimental conditions to infer gross primary production. Typically, three identical transparent vessels are filled with sample water and stoppered. The first is analysed immediately and used to determine the initial oxygen concentration; usually this is done by performing a Winkler titration. The other two vessels are incubated, one each in under light and darkened. After a fixed period of time, the experiment ends, and the oxygen concentration in both vessels is measured. As photosynthesis has not taken place in the dark vessel, it provides a measure of respiration. The light vessel permits both photosynthesis and respiration, so provides a measure of net photosynthesis (i.e. oxygen production via photosynthesis subtract oxygen consumption by respiration). Gross primary production is then obtained by subtracting oxygen consumption in the dark vessel from net oxygen production in the light vessel. Year 1927 (MCMXXVII) was a common year starting on Saturday (link will display full calendar) of the Gregorian calendar. ... Carbon-14 is the radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen and Sam Ruben. ... A stopper is a truncated conical piece of rubber or cork used to close off a glass tube, piece of laboratory glassware, a wine bottle or barrel and other containers with orifices. ... The Winkler test is used to determine the level of dissolved oxygen in fresh water samples. ...

The technique of using ¹⁴C incorporation (added as labelled Na₂CO₃) to infer primary production is most commonly used today because it is sensitive, and can be used in all ocean environments. As ¹⁴C is radioactive (via beta decay), it is relatively straightforward to measure its incorporation in organic material using devices such as scintillation counters. Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... A scintillation counter measures ionizing radiation. ...

Depending upon the incubation time chosen, net or gross primary production can be estimated. Gross primary production is best estimated using relatively short incubation times (1 hour or less), since the loss of incorporated ¹⁴C (by respiration and organic material excretion / exudation) will be more limited. Net primary production is the fraction of gross production remaining after these loss processes have consumed some of the fixed carbon.

Loss processes can range between 10-60% of incorporated ¹⁴C according to the incubation period, ambient environmental conditions (especially temperature) and the experimental species used. Aside from those caused by the physiology of the experimental subject itself, potential losses due to the activity of consumers also need to be considered. This is particularly true in experiments making use of natural assemblages of microscopic autotrophs, where it is not possible to isolate them from their consumers. For other uses, see Species (disambiguation). ...

Global

As primary production in the biosphere is an important part of the carbon cycle, estimating it at the global scale is important in Earth system science. However, quantifying primary production at this scale is difficult because of the range of habitats on Earth, and because of the impact of weather events (availability of sunlight, water) on its variability. For other uses, see Biosphere (disambiguation). ... For the thermonuclear reaction involving carbon that helps power stars, see CNO cycle. ... Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. ... Habitat (which is Latin for it inhabits) is the place where a particular species live and grow. ... For the geological process, see Weathering or Erosion. ...

Using satellite-derived estimates of the normalised difference vegetation index (NDVI) for terrestrial habitats and sea-surface chlorophyll for the oceans, it is estimated that the total (photoautotrophic) primary production for the Earth was 104.9 Gt C/yr ^[9]. Of this, 56.4 Gt C/yr (53.8%), was the product of terrestrial organisms, while the remaining 48.5 Gt C/yr, was accounted for by oceanic production. For other uses, see Satellite (disambiguation). ... Normalized Difference Vegetation Index (NDVI) is determined by measuring the ratio between visible and near infrared light reflected by the earth surface from satellites. ... Chlorophyll gives leaves their green color Space-filling model of the chlorophyll molecule Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... A tonne or metric ton (symbol t), sometimes referred to as a metric tonne, is a measurement of mass equal to 1,000 kilograms. ...

In areal terms, it was estimated that land production was approximately 426 g C/m²/yr (excluding areas with permanent ice cover), while that for the oceans was 140 g C/m²/yr. Another significant difference between the land and the oceans lies in their standing stocks - while accounting for almost half of total production, oceanic autotrophs only account for about 0.2% of the total biomass. This article is about the physical quantity. ...

References

1. ^ Martin, J. H. and Fitzwater, S. E. (1988) Iron-deficiency limits phytoplankton growth in the Northeast Pacific Subarctic. Nature 331, 341-343
2. ^ H. Haberl, et al. (2007). "Quantifying and mapping the human appropriation of net primary production in earth's terrestrial ecosystems". Proc. Natl Acad. Sci. USA (online early edition). DOI:10.1073/pnas.0704243104. 
3. ^ ^{a b c} Clark, D A; Brown, S; Kicklighter, D W; Chambers, J Q; Thomlinson, J R; Ni, J (2001). "Measuring net primary production in forests: Concepts and field methods". Ecological Applications 11: 356-370. 
4. ^ ^{a b} Scurlock, J. M. O.; Johnson, K; Olson, R. J. (2002). "Estimating net primary productivity from grassland biomass dynamics measurements". Global Change Biology 8: 736. DOI:10.1046/j.1365-2486.2002.00512.x. 
5. ^ Leith, Helmut; Robert Harding Whittaker (1975). Primary Productivity of the Biosphere. New York: Springer-Verlag. ISBN 0387070834. 
6. ^ Marra, J. (2002), pp. 78-108. In: Williams, P. J. leB., Thomas, D. N., Reynolds, C. S. (Eds.), Phytoplankton Productivity:Carbon Assimilation in Marine and Freshwater Ecosystems. Blackwell, Oxford, UK
7. ^ Steeman-Nielsen, E. (1951) Measurement of production of organic matter in sea by means of carbon-14. Nature 267, 684–685
8. ^ Steeman-Nielsen, E. (1952). The use of radioactive carbon (C14) for measuring organic production in the sea. J. Cons. Int. Explor. Mer. 18, 117-140
9. ^ Field, C. B., Behrenfeld, M. J., Randerson, J. T. and Falkowski, P. (1998) Primary production of the Biosphere: Integrating Terrestrial and Oceanic Components. Science 281, 237-240

The Proceedings of the National Academy of Sciences (USA), mostly commonly referred to as PNAS, is the official publication of the National Academy of Sciences of the United States of America. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... The Springer-Verlag (pronounced SHPRING er FAIR lahk) was a worldwide publishing company base in Germany. ...

See also

• Biological pump
• Diatom
• f-ratio

In oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the oceans interior. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... In oceanic biogeochemistry, the f-ratio is the fraction of total primary production fuelled by nitrate (as opposed to that fuelled by other nitrogen compounds such as ammonium). ...

External links

• Plots of seasonal primary production, from Field et al. (1998)
• Animation of global primary production, based on Behrenfeld et al. (2001)