In ecology, the term productivity refers to the rate of generation of biomass in an ecosystem, usually expressed in units of mass per volume (unit surface) per unit of time, such as grams per square metre per day (g m−2 d−1). The unit of mass can relate to dry matter or to the mass of generated carbon. The productivity of autotrophs, such as plants, is called primary productivity, while the productivity of heterotrophs, such as animals, is called secondary productivity.[1]

The productivity of an ecosystem is influenced by a wide range of factors, including nutrient availability, temperature, and water availability. Understanding ecological productivity is vital because it provides insights into how ecosystems function and the extent to which they can support life.[2] Productivity is typically divided into two categories: primary and secondary productivity.

Primary production

Primary production is the synthesis of organic material from inorganic molecules. Primary production in most ecosystems is dominated by the process of photosynthesis, In which organisms synthesize organic molecules from sunlight, H2O, and CO2.[3] Aquatic primary productivity refers to the production of organic matter, such as phytoplankton, aquatic plants, and algae, in aquatic ecosystems, which include oceans, lakes, and rivers. Terrestrial primary productivity refers to the organic matter production that takes place in terrestrial ecosystems such as forests, grasslands, and wetlands.

Primary production is divided into Net Primary Production (NPP) and Gross Primary Production (GPP). Gross primary production measures all carbon assimilated into organic molecules by primary producers.[4] Net primary production measures the organic molecules by primary producers. Net primary production also measures the amount of carbon assimilated into organic molecules by primary producers, but does not include organic molecules that are then broken down again by these organism for biological processes such as cellular respiration.[5] The formula used to calculate NPP is net primary production = gross primary production - respiration.

Primary producers

Photoautotrophs

Organisms that rely on light energy to fix carbon, and thus participate in primary production, are referred to as photoautotrophs.[6]

Photoautotrophs exists across the tree of life. Many bacterial taxa are known to be photoautotrophic such as cyanobacteria[7] and some Pseudomonadota (formerly proteobacteria).[8] Eukaryotic organisms gained the ability to participate in photosynthesis through the development of plastids derived from endosymbiotic relationships.[9] Archaeplastida, which includes red algae, green algae, and plants, have evolved chloroplasts originating from an ancient endosymbiotic relationship with an Alphaproteobacteria.[10] The productivity of plants, while being photoautotrophs, is also dependent on factors such as salinity and abiotic stressors from the surrounding environment.[11] The rest of the eukaryotic photoautotrophic organisms are within the SAR clade (Comprising Stramenopila, Alveolata, and Rhizaria). Organisms in the SAR clade that developed plastids did so through a secondary or a tertiary endosymbiotic relationships with green algae and/or red algae.[12] The SAR clade includes many aquatic and marine primary producers such as Kelp, Diatoms, and Dinoflagellates.[12]

Lithoautotrophs

The other process of primary production is lithoautotrophy. Lithoautotrophs use reduced chemical compounds such as hydrogen gas, hydrogen sulfide, methane, or ferrous ion to fix carbon and participate in primary production. Lithoautotrophic organisms are prokaryotic and are represented by members of both the bacterial and archaeal domains.[13] Lithoautotrophy is the only form of primary production possible in ecosystems without light such as ground-water ecosystems,[14] hydrothermal vent ecosystems,[15] soil ecosystems,[16] and cave ecosystems.[17]

Secondary production

Secondary production is the generation of biomass of heterotrophic (consumer) organisms in a system. This is driven by the transfer of organic material between trophic levels, and represents the quantity of new tissue created through the use of assimilated food. Secondary production is sometimes defined to only include consumption of primary producers by herbivorous consumers[18] (with tertiary production referring to carnivorous consumers),[19] but is more commonly defined to include all biomass generation by heterotrophs.[1]

Organisms responsible for secondary production include animals, protists, fungi and many bacteria.

Secondary production can be estimated through a number of different methods including increment summation, removal summation, the instantaneous growth method and the Allen curve method.[20] The choice between these methods will depend on the assumptions of each and the ecosystem under study. For instance, whether cohorts should be distinguished, whether linear mortality can be assumed and whether population growth is exponential.

Net ecosystem production is defined as the difference between gross primary production (GPP) and ecosystem respiration.[21] The formula to calculate net ecosystem production is NEP = GPP - respiration (by autotrophs) - respiration (by heterotrophs).[22] The key difference between NPP and NEP is that NPP focuses primarily on autotrophic production, whereas NEP incorporates the contributions of other aspects of the ecosystem to the total carbon budget.[23]

Productivity

Following is the list of ecosystems in order of decreasing productivity.

Producer Biomass productivity (gC/m²/yr)
Swamps and Marshes 2,500
Coral reefs 2,000
Algal beds 2,000
River estuaries 1,800
Temperate forests 1,250
Cultivated lands 650
Tundras 140
Open ocean 125

Species diversity and productivity relationship

The connection between plant productivity and biodiversity is a significant topic in ecology, although it has been controversial for decades. Both productivity and species diversity are constricted by other variables such as climate, ecosystem type, and land use intensity.[24] According to some research on the correlation between plant diversity and ecosystem functioning is that productivity increases as species diversity increases.[25] One reasoning for this is that the likelihood of discovering a highly productive species increases as the number of species initially present in an ecosystem increases.[25][26]

Other researchers believe that the relationship between species diversity and productivity is unimodal within an ecosystem.[27] A 1999 study on grassland ecosystems in Europe, for example, found that increasing species diversity initially increased productivity but gradually leveled off at intermediate levels of diversity.[28] More recently, a meta-analysis of 44 studies from various ecosystem types observed that the interaction between diversity and production was unimodal in all but one study.[29]

Human interactions

Anthropogenic activities (human activities) have impacted the productivity and biomass of several ecosystems. Examples of these activities include habitat modification, freshwater consumption, an increase in nutrients due to fertilizers, and many others.[30] Increased nutrients can stimulate an algal bloom in waterbodies, increasing primary production but making the ecosystem less stable.[31] This would raise secondary production and have a trophic cascade effect across the food chain, ultimately increasing overall ecosystem productivity.[32]

See also

References

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  2. ↑ US EPA, ORD (2017-11-01). "Ecological Condition". www.epa.gov. Retrieved 2023-04-27.
  3. ↑ Johnson, Matthew P. (2016-10-26). "Photosynthesis". Essays in Biochemistry. 60 (3): 255–273. doi:10.1042/EBC20160016. ISSN 0071-1365. PMC 5264509. PMID 27784776.
  4. ↑ Woodwell, George (1 August 2015). "Primary Production in Terrestrial Ecosystems". American Zoologist. 8: 19–30. doi:10.1093/icb/8.1.19.
  5. ↑ Yu, Bo; Chen, Fang (2016-08-02). "The global impact factors of net primary production in different land cover types from 2005 to 2011". SpringerPlus. 5 (1): 1235. doi:10.1186/s40064-016-2910-1. ISSN 2193-1801. PMC 4971002. PMID 27536518.
  6. ↑ Scognamiglio, Viviana; Giardi, Maria Teresa; Zappi, Daniele; Touloupakis, Eleftherios; Antonacci, Amina (January 2021). "Photoautotrophs–Bacteria Co-Cultures: Advances, Challenges and Applications". Materials. 14 (11): 3027. Bibcode:2021Mate...14.3027S. doi:10.3390/ma14113027. ISSN 1996-1944. PMC 8199690. PMID 34199583.
  7. ↑ Singh, Jay Shankar; Kumar, Arun; Rai, Amar N.; Singh, Devendra P. (2016). "Cyanobacteria: A Precious Bio-resource in Agriculture, Ecosystem, and Environmental Sustainability". Frontiers in Microbiology. 7: 529. doi:10.3389/fmicb.2016.00529. ISSN 1664-302X. PMC 4838734. PMID 27148218.
  8. ↑ Tang, Kuo-Hsiang; Tang, Yinjie J.; Blankenship, Robert Eugene (2011). "Carbon Metabolic Pathways in Phototrophic Bacteria and Their Broader Evolutionary Implications". Frontiers in Microbiology. 2: 165. doi:10.3389/fmicb.2011.00165. PMC 3149686. PMID 21866228.
  9. ↑ Margulis, L. (1968-09-06). "Evolutionary criteria in thallophytes: a radical alternative". Science. 161 (3845): 1020–1022. Bibcode:1968Sci...161.1020M. doi:10.1126/science.161.3845.1020. PMID 17812802. S2CID 21929905.
  10. ↑ Ford Doolittle, W (1998-12-01). "You are what you eat: a gene transfer ratchet could account for bacterial genes in eukaryotic nuclear genomes". Trends in Genetics. 14 (8): 307–311. doi:10.1016/S0168-9525(98)01494-2. PMID 9724962.
  11. ↑ Harman, Gary; Khadka, Ram; Doni, Febri; Uphoff, Norman (2021). "Benefits to Plant Health and Productivity From Enhancing Plant Microbial Symbionts". Frontiers in Plant Science. 11: 610065. doi:10.3389/fpls.2020.610065. ISSN 1664-462X. PMC 8072474. PMID 33912198.
  12. 1 2 Grattepanche, Jean-David; Walker, Laura M.; Ott, Brittany M.; Paim Pinto, Daniela L.; Delwiche, Charles F.; Lane, Christopher E.; Katz, Laura A. (2018). "Microbial Diversity in the Eukaryotic SAR Clade: Illuminating the Darkness Between Morphology and Molecular Data". BioEssays. 40 (4): e1700198. doi:10.1002/bies.201700198. PMID 29512175. S2CID 3731086.
  13. ↑ Lazar, Cassandre Sara; Stoll, Wenke; Lehmann, Robert; Herrmann, Martina; Schwab, Valérie F.; Akob, Denise M.; Nawaz, Ali; Wubet, Tesfaye; Buscot, François (2017-06-13). "Archaeal Diversity and CO2 Fixers in Carbonate-/Siliciclastic-Rock Groundwater Ecosystems". Archaea. 2017: 1–13. doi:10.1155/2017/2136287. PMC 5485487. PMID 28694737.
  14. ↑ Griebler, C.; Lueders, T. (2009). "Microbial biodiversity in groundwater ecosystems". Freshwater Biology. 54 (4): 649–677. doi:10.1111/j.1365-2427.2008.02013.x.
  15. ↑ Sievert, Stefan; Vetriani, Costantino (2012-03-01). "Chemoautotrophy at Deep-Sea Vents: Past, Present, and Future". Oceanography. 25 (1): 218–233. doi:10.5670/oceanog.2012.21. hdl:1912/5172.
  16. ↑ Drake, Henrik; Ivarsson, Magnus (2018-01-01). "The role of anaerobic fungi in fundamental biogeochemical cycles in the deep biosphere". Fungal Biology Reviews. 32 (1): 20–25. doi:10.1016/j.fbr.2017.10.001. S2CID 89881167.
  17. ↑ Galassi, Diana M. P.; Fiasca, Barbara; Di Lorenzo, Tiziana; Montanari, Alessandro; Porfirio, Silvano; Fattorini, Simone (2017-03-01). "Groundwater biodiversity in a chemoautotrophic cave ecosystem: how geochemistry regulates microcrustacean community structure". Aquatic Ecology. 51 (1): 75–90. doi:10.1007/s10452-016-9599-7. S2CID 41641625.
  18. ↑ "Definition of term: "Secondary production"". The Glossary Table. FishBase. Retrieved 2009-12-03.
  19. ↑ "Definition of term: "Tertiary production"". The Glossary Table. FishBase. Retrieved 2009-12-03.
  20. ↑ Allen, K.R. (1951). "The Horokiwi Stream: A study of a trout population". New Zealand Marine Department Fisheries Bulletin. 10: 1–238.
  21. ↑ Lovett, Gary M.; Cole, Jonathan J.; Pace, Michael L. (2006-01-30). "Is Net Ecosystem Production Equal to Ecosystem Carbon Accumulation?". Ecosystems. 9 (1): 152–155. doi:10.1007/s10021-005-0036-3. ISSN 1432-9840. S2CID 5890190.
  22. ↑ "The Flow of Energy: Primary Production". www.globalchange.umich.edu. Retrieved 2023-04-28.
  23. ↑ Randerson, J. T.; Chapin, F. S.; Harden, J. W.; Neff, J. C.; Harmon, M. E. (2002-08-01). "Net Ecosystem Production: A Comprehensive Measure of Net Carbon Accumulation by Ecosystems". Ecological Applications. 12 (4): 937–947. doi:10.1890/1051-0761(2002)012[0937:NEPACM]2.0.CO;2. ISSN 1051-0761. S2CID 54714382.
  24. ↑ Brun, Philipp; Zimmermann, Niklaus E.; Graham, Catherine H.; Lavergne, Sébastien; Pellissier, Loïc; Münkemüller, Tamara; Thuiller, Wilfried (2019-12-12). "The productivity-biodiversity relationship varies across diversity dimensions". Nature Communications. 10 (1): 5691. Bibcode:2019NatCo..10.5691B. doi:10.1038/s41467-019-13678-1. ISSN 2041-1723. PMC 6908676. PMID 31831803.
  25. 1 2 van Ruijven, Jasper; Berendse, Frank (2005-01-18). "Diversity–productivity relationships: Initial effects, long-term patterns, and underlying mechanisms". Proceedings of the National Academy of Sciences. 102 (3): 695–700. Bibcode:2005PNAS..102..695V. doi:10.1073/pnas.0407524102. ISSN 0027-8424. PMC 545547. PMID 15640357.
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  27. ↑ Fraser, Lauchlan H.; Pither, Jason; Jentsch, Anke; Sternberg, Marcelo; Zobel, Martin; Askarizadeh, Diana; Bartha, Sandor; Beierkuhnlein, Carl; Bennett, Jonathan A.; Bittel, Alex; Boldgiv, Bazartseren; Boldrini, Ilsi I.; Bork, Edward; Brown, Leslie; Cabido, Marcelo (2015). "Worldwide evidence of a unimodal relationship between productivity and plant species richness". Science. 349 (6245): 302–305. Bibcode:2015Sci...349..302F. doi:10.1126/science.aab3916. hdl:11336/22771. ISSN 0036-8075. JSTOR 24748582. PMID 26185249. S2CID 11207678.
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  29. ↑ Cardinale, Bradley J.; Wright, Justin P.; Cadotte, Marc W.; Carroll, Ian T.; Hector, Andy; Srivastava, Diane S.; Loreau, Michel; Weis, Jerome J. (2007-11-13). "Impacts of plant diversity on biomass production increase through time because of species complementarity". Proceedings of the National Academy of Sciences. 104 (46): 18123–18128. Bibcode:2007PNAS..10418123C. doi:10.1073/pnas.0709069104. ISSN 0027-8424. PMC 2084307. PMID 17991772.
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  31. ↑ Carroll, Oliver; Batzer, Evan; Bharath, Siddharth; Borer, Elizabeth T.; Campana, Sofía; Esch, Ellen; Hautier, Yann; Ohlert, Timothy; Seabloom, Eric W.; Adler, Peter B.; Bakker, Jonathan D.; Biederman, Lori; Bugalho, Miguel N.; Caldeira, Maria; Chen, Qingqing (2021-12-27). Penuelas, Josep (ed.). "Nutrient identity modifies the destabilising effects of eutrophication in grasslands". Ecology Letters. 25 (4): 754–765. doi:10.1111/ele.13946. hdl:1874/419064. ISSN 1461-023X. PMID 34957674. S2CID 245517664.
  32. ↑ Conley, Daniel J.; Paerl, Hans W.; Howarth, Robert W.; Boesch, Donald F.; Seitzinger, Sybil P.; Havens, Karl E.; Lancelot, Christiane; Likens, Gene E. (2009-02-20). "Controlling Eutrophication: Nitrogen and Phosphorus". Science. 323 (5917): 1014–1015. doi:10.1126/science.1167755. ISSN 0036-8075. PMID 19229022. S2CID 28502866.
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