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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Soil formation / Roots, fungi and burrowers engineer soil formation

Roots, fungi and burrowers engineer soil formation

Living organisms speed soil formation: roots and mycorrhizal fungi acidify and dissolve minerals, deep roots pump cations upward to the surface, and burrowing animals mix layers.

Boundary: where this process starts

Starts with: Roots and mycorrhizal fungi release protons and organic anions that dissolve minerals

Boundary: where it ends

Ends after: Burrowing animals and tree throw mix material between layers (bioturbation)

PARTICIPANTSRESOURCESPlant rootsMycorrhizalfungiSoil faunaPlantsOrganic acidsPrimarymineralsPhosphorusCalciumDead organicmatterImpact +3 of 5. Click for details and evidence.living roots in rock-derivedImpact +3 of 5. Click for details and evidence.released cations and P takenImpact +3 of 5. Click for details and evidence.litter at the surface is mixImpact +3 of 5. Click for details and evidence.mixed, nutrient-enriched uppImpact +3 of 5. Click for details and evidence.↻ reinforces · weak · 0.15 more plant growthRoots and mycorrhizal fungi release protons and organic anions that dissolve minerals: makes Organic acidsmakesRoots and mycorrhizal fungi release protons and organic anions that dissolve minerals: uses up Primary mineralsuses upRoots and mycorrhizal fungi release protons and organic anions that dissolve minerals: uses PhosphorusDeep roots take up cations from subsoil and return them in litter (biological pumping): uses up Calciumuses upDeep roots take up cations from subsoil and return them in litter (biological pumping): makes Dead organic mattermakesreleased from roots andhyphaeOrganic acids: released from roots and hyphaedissolved by organicanionsPrimary minerals: dissolved by organic anionsmobilised from mineralsPhosphorus: mobilised from mineralspumped up from subsoilCalcium: pumped up from subsoilreturned to the surfacein litterDead organic matter: returned to the surface in litterStart: Roots, fungi andburrowers engineer soilformationSTARTStart: Roots, fungi and burrowers engineer soil formationEnd: Roots, fungi andburrowers engineer soilformationENDEnd: Roots, fungi and burrowers engineer soil formationRoots and mycorrhizalfungi release protonsand organic anions th…📄2 ↗1Roots and mycorrhizal fungi release protons and organic anions that dissolve mineralsDeep roots take upcations from subsoiland return them …📄1Deep roots take up cations from subsoil and return them in litter (biological pumping)Burrowing animals andtree throw mix materialbetween laye…📄1Burrowing animals and tree throw mix material between layers (bioturbation)
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)
What am I looking at? The concepts on every map
Participant
Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
Resource
Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
Step
One thing that happens in a process. Every step has at least one participant and carries evidence.
Decision fork
A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
Loop
A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
Size of impact
Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
Evidence
The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
Boundary
Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
Subprocess
A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
Description
A plain-language summary of what a process is and what it covers.
Hypothesis
A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.

Every step, with its evidence

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Roots and mycorrhizal fungi release protons and organic anions that dissolve minerals
Plant rootsMycorrhizal fungiOrganic acidsPrimary mineralsPhosphorus
Evidence (2) · added by Skeptic
  • Hinsinger 2001, Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced chemical changes, Plant and Soil, doi:10.1023/a:1013351617532: Root-induced pH changes and carboxylate exudation mobilise inorganic P from soil minerals. (confidence 0.85)
  • Taylor et al. 2009, Biological weathering and the long-term carbon cycle: integrating mycorrhizal evolution and function, Geobiology, doi:10.1111/j.1472-4669.2009.00194.x: Mycorrhizal fungi accelerate mineral weathering relative to non-mycorrhizal roots. (confidence 0.8)
Deep roots take up cations from subsoil and return them in litter (biological pumping)
PlantsPlant rootsCalciumDead organic matter
Evidence (1) · added by Skeptic
  • Dijkstra & Smits 2002, Tree species effects on calcium cycling: the role of calcium uptake in deep soils, Ecosystems, doi:10.1007/s10021-001-0082-4: Tree species differ in Ca uptake from deep soil and its return to surface horizons through litter. (confidence 0.8)
Burrowing animals and tree throw mix material between layers (bioturbation)
Soil faunaPlantsSoil
Evidence (1) · added by Skeptic
  • Wilkinson & Humphreys 2005, Exploring pedogenesis via nuclide-based soil production rates and OSL-based bioturbation rates, Soil Research, doi:10.1071/sr04158: Bioturbation rates measured by OSL dating are comparable in scale with soil production and shape soil profiles. (confidence 0.7)