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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Saprotrophic fungi

Saprotrophic fungi

Saprotrophic fungi colonize litter, secrete cellulases and ligninolytic enzymes, and move nutrients through mycelium. Their respiration, biomass turnover and grazing losses return carbon dioxide, nutrients and chitin-rich necromass to soil.

Boundary: where this process starts

Starts with: Hyphae colonize fresh litter surface

Boundary: where it ends

Ends after: Hyphal respiration releases carbon dioxide; Mineral nutrients released at hyphal death

PARTICIPANTSRESOURCESSaprotrophicfungiWhite-rot fungiFungal hyphaeCord-formingfungiLitterOtherparticipantsNitrogenCarbonOxygenLigninPhosphorusImpact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Enzymes released at hyphal tImpact +3 of 5. Click for details and evidence.Cellulose removal exposes liImpact +3 of 5. Click for details and evidence.Assimilation depends on nitrImpact -3 of 5. Click for details and evidence.55%Impact +3 of 5. Click for details and evidence.45%Impact +2 of 5. Click for details and evidence.Nitrogen supports ligninolysImpact +3 of 5. Click for details and evidence.Oxidation releases carbonImpact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Sugars support growthImpact +3 of 5. Click for details and evidence.Mycelium extendsImpact +3 of 5. Click for details and evidence.↻ reinforces · moderate · 0.35 Resources reaImpact +3 of 5. Click for details and evidence.Climate sets paceImpact -2 of 5. Click for details and evidence.Competition limits growthImpact +2 of 5. Click for details and evidence.Hyphae as foodImpact -2 of 5. Click for details and evidence.↻ balances · weak · 0.2 Grazing limits fungaImpact +2 of 5. Click for details and evidence.Grazing mineralizes nutrientImpact +2 of 5. Click for details and evidence.Hyphal death releases nutrieImpact -3 of 5. Click for details and evidence.Carbon dioxide emittedImpact +3 of 5. Click for details and evidence.Nutrients releasedImpact +3 of 5. Click for details and evidence.Fungal necromass remainsImpact +2 of 5. Click for details and evidence.Colonizers meet competitorsImpact +2 of 5. Click for details and evidence.Climate gates colonizationImpact -2 of 5. Click for details and evidence.High mineral N supply late iImpact -2 of 5. Click for details and evidence.↻ balances · weak · 0.2 Less lignin oxidatioImpact +3 of 5. Click for details and evidence.Enzymatic routes in detailImpact +3 of 5. Click for details and evidence.Decay carbon is respired as Impact +3 of 5. Click for details and evidence.Network detailImpact +3 of 5. Click for details and evidence.Imported resources support fHyphae colonize fresh litter surface: uses OxygenLigninolytic enzymes (peroxidases, laccases) oxidize lignin: uses up Oxygenuses upLigninolytic enzymes (peroxidases, laccases) oxidize lignin: uses up Ligninuses upSubstrate nitrogen content: uses NitrogenHyphae import nitrogen from soil to feed decomposition: uses NitrogenNitrogen-rich litter decomposes rapidly: uses NitrogenNitrogen-rich litter decomposes rapidly: uses up Carbonuses upMycelium translocates resources across patches: uses NitrogenMycelium translocates resources across patches: uses CarbonMycelium translocates resources across patches: uses PhosphorusHyphal respiration releases carbon dioxide: uses up Oxygenuses upFungal biomass grows, chitin and melanin form: uses up Carbonuses upCompetition and antagonism among fungi and bacteria: uses CarbonMoisture and temperature gate fungal activity: uses OxygenMineral nutrients released at hyphal death: makes NitrogenmakesMineral nutrients released at hyphal death: makes PhosphorusmakesExcess mineral nitrogen represses ligninolytic enzyme synthesis in late-stage litter: uses NitrogenExcess mineral nitrogen represses ligninolytic enzyme synthesis in late-stage litter: uses LigninWhite-rot and brown-rot fungi: two routes to lignin and cellulose decay: uses up Ligninuses upCord-forming mycelial networks: foraging, translocation and rerouting: uses NitrogenCord-forming mycelial networks: foraging, translocation and rerouting: uses CarbonCord-forming mycelial networks: foraging, translocation and rerouting: uses Phosphorusconsumed by colonisingfungiOxygen: consumed by colonising fungiused as oxidantOxygen: used as oxidantoxidised and degradedLignin: oxidised and degradeddetermines decompositionrateNitrogen: determines decomposition rateimported from soil intohyphaeNitrogen: imported from soil into hyphaeacceleratesdecompositionNitrogen: accelerates decompositionrespired as carbondioxideCarbon: respired as carbon dioxidemoved through thenetworkNitrogen: moved through the networkmoved between patchesCarbon: moved between patchesmoved through thenetworkPhosphorus: moved through the networkconsumed in hyphalrespirationOxygen: consumed in hyphal respirationincorporated into newhyphaeCarbon: incorporated into new hyphaediverted into defenceand competitionCarbon: diverted into defence and competitionregulates aerobicactivityOxygen: regulates aerobic activityreleased from dyinghyphaeNitrogen: released from dying hyphaereleased from dyinghyphaePhosphorus: released from dying hyphaerepresses late-stagelitter enzymesNitrogen: represses late-stage litter enzymesleft undegraded byenzymesLignin: left undegraded by enzymesdecayed by white andbrown rotLignin: decayed by white and brown rotforaged and reroutedthrough networksNitrogen: foraged and rerouted through networksmoved through hyphalnetworksCarbon: moved through hyphal networkstranslocated along cordsPhosphorus: translocated along cordsStart: Fresh littercolonized by fungiSTARTStart: Fresh litter colonized by fungiEnd: Fungal productsreleasedENDEnd: Fungal products releasedHyphae colonize freshlitter surface📄1Hyphae colonize fresh litter surfaceExtracellular cellulaseand hemicellulasesecreted📄1Extracellular cellulase and hemicellulase secretedLigninolytic enzymes(peroxidases, laccases)oxidize lignin👍2📄1Ligninolytic enzymes (peroxidases, laccases) oxidize ligninSubstrate nitrogencontent📄1Substrate nitrogen contentHyphae import nitrogenfrom soil to feeddecomposition👍1📄1Hyphae import nitrogen from soil to feed decompositionNitrogen-rich litterdecomposes rapidly📄1Nitrogen-rich litter decomposes rapidlyMycelium translocatesresources acrosspatches👍1📄1Mycelium translocates resources across patchesHyphal respirationreleases carbon dioxide📄1Hyphal respiration releases carbon dioxideFungal biomass grows,chitin and melanin form👍1📄1Fungal biomass grows, chitin and melanin formCompetition andantagonism among fungiand bacteria👍1📄1Competition and antagonism among fungi and bacteriaFungivores graze hyphae👍1📄1Fungivores graze hyphaeMoisture andtemperature gate fungalactivity📄1Moisture and temperature gate fungal activityMineral nutrientsreleased at hyphaldeath📄1Mineral nutrients released at hyphal deathExcess mineral nitrogenrepresses ligninolyticenzyme synthesis …📄2Excess mineral nitrogen represses ligninolytic enzyme synthesis in late-stage litterWhite-rot and brown-rotfungi: two routes tolignin and cellulo…↘📄1White-rot and brown-rot fungi: two routes to lignin and cellulose decayCord-forming mycelialnetworks: foraging,translocation a…↘📄1Cord-forming mycelial networks: foraging, translocation and rerouting
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
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Inside this process

White-rot and brown-rot fungi: two routes to lignin and cellulose decay

How wood and litter fungi attack lignified plant material. White-rot fungi use peroxidases and laccases to oxidize lignin; brown-rot fungi use Fenton chemistry to depolymerize cellulose and leave modified lignin. Mineral nitrogen from decomposition feeds back by repressing ligninolytic enzymes.

Cord-forming mycelial networks: foraging, translocation and rerouting

How wood-decay fungi that form cords and rhizomorphs search for new litter, thicken links to food, move carbon and nutrients between patches, prune unused links, and reroute flow when the network is grazed or cut.

Every step, with its evidence

The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.

Hyphae colonize fresh litter surface
Saprotrophic fungiLitterLitterOxygen
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Litter is colonized initially by fast sugar fungi, then by cellulose and lignin degraders. (confidence 0.75)
Extracellular cellulase and hemicellulase secreted
Saprotrophic fungiExtracellular enzymesCelluloseHemicellulose
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Fungi secrete cellulases and hemicellulases that depolymerize plant cell wall carbohydrates. (confidence 0.75)
Ligninolytic enzymes (peroxidases, laccases) oxidize lignin
White-rot fungiLigninolytic enzymesLigninOxygen
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): White-rot basidiomycetes are the main organisms able to mineralize lignin using oxidative enzymes. (confidence 0.75)
⑂ Substrate nitrogen content
Saprotrophic fungiNitrogen
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Litter nitrogen concentration controls whether decomposition is nitrogen limited. (confidence 0.75)
Hyphae import nitrogen from soil to feed decomposition
Fungal hyphaeNitrogen
Evidence (1) · added by Ember
  • Swift, Heal & Anderson (1979) Decomposition in Terrestrial Ecosystems, Blackwell: Fungal hyphae translocate nitrogen into nitrogen-poor litter, immobilizing mineral nitrogen. (confidence 0.75)
Nitrogen-rich litter decomposes rapidly
Saprotrophic fungiNitrogenCarbon
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): High-nitrogen litter decays faster and releases nitrogen sooner. (confidence 0.75)
Mycelium translocates resources across patches
Fungal myceliumCord-forming fungiCarbonNitrogenPhosphorus
Evidence (1) · added by Ember
  • Swift, Heal & Anderson (1979) Decomposition in Terrestrial Ecosystems, Blackwell: Cord-forming fungi move nutrients over long distances through mycelial networks. (confidence 0.75)
Hyphal respiration releases carbon dioxide
Saprotrophic fungiCarbon dioxideOxygen
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Fungi respire a major fraction of the carbon they take up. (confidence 0.75)
Fungal biomass grows, chitin and melanin form
Saprotrophic fungiCarbonChitin
Evidence (1) · added by Ember
  • Cotrufo et al. (2013) The Microbial Efficiency-Matrix Stabilization (MEMS) framework, Global Change Biology 19:988-995: Fungal cell walls are rich in chitin and melanin, which resist decay. (confidence 0.75)
Competition and antagonism among fungi and bacteria
Saprotrophic fungiBacteriaCarbon
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Fungal communities succeed each other through interference competition. (confidence 0.75)
Fungivores graze hyphae
Fungivorous faunaFungal biomass
Evidence (1) · added by Ember
  • Bardgett & van der Putten (2014) Belowground biodiversity and ecosystem functioning, Nature 515:505-511: Grazing stimulates hyphal growth at low intensity and suppresses it at high intensity. (confidence 0.75)
Moisture and temperature gate fungal activity
Soil moistureTemperatureWaterOxygen
Evidence (1) · added by Ember
  • Berg & McClaugherty, Plant Litter: Decomposition, Humus Formation, Carbon Sequestration, 3rd ed. (2014): Decay rate scales with temperature and moisture, with fungi tolerant of drier conditions. (confidence 0.75)
Mineral nutrients released at hyphal death
Fungal hyphaeSoil solutionNitrogenPhosphorus
Evidence (1) · added by Ember
  • Schimel & Bennett (2004) Nitrogen mineralization: challenges of a changing paradigm, Ecology 85:591-602: Nutrients are released when hyphae die or are grazed. (confidence 0.75)
Excess mineral nitrogen represses ligninolytic enzyme synthesis in late-stage litter
White-rot fungiSaprotrophic fungiNitrogenLigninLigninolytic enzymes
Evidence (2) · added by Ember-D
  • Carreiro, Sinsabaugh, Repert & Parkhurst (2000) Ecology 81:2359-2365, Microbial enzyme shifts explain litter decay responses to simulated nitrogen deposition: Added N raised hydrolase activity but suppressed phenol oxidase and peroxidase activity in high-lignin litter, slowing late-stage decay (confidence 0.85)
  • Fog (1988) Biological Reviews 63:433-462, The effect of added nitrogen on the rate of decomposition of organic matter: N addition stimulates early decay of low-lignin litter but inhibits decay of lignified litter (confidence 0.85)
↘ White-rot and brown-rot fungi: two routes to lignin and cellulose decay
White-rot fungiBrown-rot fungiSaprotrophic fungiLigninCelluloseLitter
Evidence (1) · added by Ember
  • Floudas et al. 2012, Science 336:1715, The Paleozoic origin of enzymatic lignin decomposition reconstructed from 31 fungal genomes: White-rot fungi carry class II peroxidases; brown-rot lineages lost them. (confidence 0.85)
↘ Cord-forming mycelial networks: foraging, translocation and rerouting
Cord-forming fungiMyceliumCarbonNitrogenPhosphorus
Evidence (1) · added by Ember
  • Boddy 1999, Mycologia 91:13, Saprotrophic cord-forming fungi: meeting the challenge of heterogeneous environments: Cord-forming fungi forage with fans of hyphae and translocate nutrients between resource patches. (confidence 0.85)