Editing Decomposer (section)

== Terrestrial decomposers ==
In terrestrial environments, decomposition happens mainly in or on soil, and decomposers' activities lead to increased [[soil fertility]].<ref>{{Cite web |title=Soil Carbon Storage {{!}} Learn Science at Scitable |url=https://www.nature.com/scitable/knowledge/library/soil-carbon-storage-84223790/ |access-date=2024-11-30 |website=www.nature.com |language=en}}</ref> The main nutrients plants have to derive from soils are nitrogen, phosphorus, and potassium, and all three have to be available in forms that are accessible to and absorbable by the plants. Decomposition is the process of breaking large molecules in dead matter down into smaller molecules that nearby plants are able to take up through their roots. Some steps of the process occur via mechanical grinding and churning by things like earthworms and plant roots in a process called [[bioturbation]].<ref>{{Cite journal |last1=Ruiz |first1=Siul |last2=Or |first2=Dani |last3=Schymanski |first3=Stanislaus J. |date=2015-06-18 |title=Soil Penetration by Earthworms and Plant Roots—Mechanical Energetics of Bioturbation of Compacted Soils |journal=PLOS ONE |language=en |volume=10 |issue=6 |pages=e0128914 |doi=10.1371/journal.pone.0128914 |doi-access=free |issn=1932-6203 |pmc=4472233 |pmid=26087130|bibcode=2015PLoSO..1028914R }}</ref> Further breakdown, beyond those physical means, requires the presence of enzymes. The paired processes are akin to what occurs in mammal [[Gastrointestinal tract|digestive tracts]]: food is mechanically ground up by teeth, and then chemically broken down by enzymes.

A given organism's ability to contribute to decomposition is largely dependent on what enzymes that organism possesses. Enzymes for the digestion of molecules like fats, proteins, and starch are widespread and many organisms, from microbes to mammals, have them.<ref>{{Cite journal |last1=Griffiths |first1=Hannah M. |last2=Ashton |first2=Louise A. |last3=Parr |first3=Catherine L. |last4=Eggleton |first4=Paul |date=2021 |title=The impact of invertebrate decomposers on plants and soil |url=https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17553 |journal=New Phytologist |language=en |volume=231 |issue=6 |pages=2142–2149 |doi=10.1111/nph.17553 |pmid=34128548 |bibcode=2021NewPh.231.2142G |hdl=10072/406155 |issn=1469-8137|hdl-access=free }}</ref> As a result, those molecules are the first to decompose in the environment. [[Cellulose]] in dead plants is broken down by cellulase enzymes, which are present in far fewer organisms, and the enzymes needed to digest [[lignin]], a chemically complex molecule in woody trees and shrubs, in fewer still.<ref>{{Cite journal |last1=Nakazawa |first1=Takehito |last2=Yamaguchi |first2=Iori |last3=Zhang |first3=Yufan |last4=Saka |first4=Chinami |last5=Wu |first5=Hongli |last6=Kayama |first6=Keita |last7=Kawauchi |first7=Moriyuki |last8=Sakamoto |first8=Masahiro |last9=Honda |first9=Yoichi |date=October 2023 |title=Experimental evidence that lignin-modifying enzymes are essential for degrading plant cell wall lignin by Pleurotus ostreatus using CRISPR/Cas9 |url=https://pubmed.ncbi.nlm.nih.gov/37218079/ |journal=Environmental Microbiology |volume=25 |issue=10 |pages=1909–1924 |doi=10.1111/1462-2920.16427 |issn=1462-2920 |pmid=37218079|bibcode=2023EnvMi..25.1909N |doi-access=free }}</ref>
[[File:Fungi_on_fallen_Birch_Branch_-_geograph.org.uk_-_239255.jpg|thumb|Fungi acting as decomposers of a fallen tree branch]]

=== Fungi ===
The primary decomposer of litter in many [[ecosystem]]s is [[fungi]].<ref>{{Cite journal|last1=Godbold|first1=Douglas L.|last2=Hoosbeek|first2=Marcel R.|last3=Lukac|first3=Martin|last4=Cotrufo|first4=M. Francesca|author-link4=M. Francesca Cotrufo|last5=Janssens|first5=Ivan A.|last6=Ceulemans|first6=Reinhart|last7=Polle|first7=Andrea|last8=Velthorst|first8=Eef J.|last9=Scarascia-Mugnozza|first9=Giuseppe|last10=De Angelis|first10=Paolo|last11=Miglietta|first11=Franco|date=2006-03-01|title=Mycorrhizal Hyphal Turnover as a Dominant Process for Carbon Input into Soil Organic Matter|url=https://doi.org/10.1007/s11104-005-3701-6|journal=Plant and Soil|language=en|volume=281|issue=1|pages=15–24|doi=10.1007/s11104-005-3701-6|bibcode=2006PlSoi.281...15G |s2cid=24926892 |issn=1573-5036|url-access=subscription}}</ref><ref>{{Cite journal|last1=Talbot|first1=J. M.|last2=Allison|first2=S. D.|last3=Treseder|first3=K. K.|date=2008|title=Decomposers in disguise: mycorrhizal fungi as regulators of soil C dynamics in ecosystems under global change|journal=Functional Ecology|language=en|volume=22|issue=6|pages=955–963|doi=10.1111/j.1365-2435.2008.01402.x|issn=1365-2435|doi-access=free|bibcode=2008FuEco..22..955T }}</ref> Unlike [[bacteria]], which are unicellular organisms and are decomposers as well, most [[saprotroph]]ic fungi grow as a branching network of [[hypha]]e. Bacteria are restricted to growing and feeding on the exposed surfaces of organic matter, but fungi can use their hyphae to penetrate larger pieces of organic matter below the surface. Additionally, only [[wood-decay fungus|wood-decay fungi]] have evolved [[Lignin-modifying enzyme|lignin-modifying enzymes]] necessary to decompose [[lignin]].<ref>{{cite journal|last1=Blanchette|first1=Robert|title=Delignification by Wood-Decay Fungi|journal=Annual Review of Phytopathology|date=September 1991|volume=29|pages=281–403|doi=10.1146/annurev.py.29.090191.002121}}</ref> These two factors make fungi the primary decomposers in [[forest]]s, where litter has high concentrations of lignin and often occurs in [[coarse woody debris|large pieces]] like fallen trees and branches. Fungi decompose organic matter by releasing enzymes to break down the decaying material, after which they absorb the nutrients in the decaying material.<ref name="berkeley">{{cite web |url=http://www.ucmp.berkeley.edu/fungi/fungilh.html |title=Fungi: Life History and Ecology |first1=Ben |last1=Waggoner |first2=Brian |last2=Speer |work=Introduction to the Funge=24 January 2014}}</ref> Hyphae are used to break down matter and absorb nutrients and are also used in reproduction.