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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Aggregate formation and pore structure / Bioturbation: fauna remodel soil structure

Bioturbation: fauna remodel soil structure

How earthworms, ants, termites and burrowing mammals mix soil and create burrows and casts that remodel structure, pores and organic matter distribution.

Boundary: where this process starts

Starts with: Earthworms ingest soil and litter and mix organic with mineral material

Boundary: where it ends

Ends after: Net effect on structure depends on species, soil and management; Structure improved: stable casts, interconnected pores, mixed organic matter

PARTICIPANTSRESOURCESEarthwormsAntsTermitesBurrowingmammalsGut microbesOtherparticipantsSoil aggregatesPore spaceSoil organicmatterClay mineralsPlant litterImpact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact 02 of 5. Click for details and evidence.Impact 01 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +2 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.60% structure improvesImpact -2 of 5. Click for details and evidence.15% smearing or surface sealImpact -3 of 5. Click for details and evidence.25% ↻ balances · moderate · 0.3 litter layerImpact +3 of 5. Click for details and evidence.↻ reinforces · moderate · 0.3Impact -2 of 5. Click for details and evidence.↻ balances · moderate · 0.3Impact +3 of 5. Click for details and evidence.Earthworms ingest soil and litter and mix organic with mineral material: uses Soil organic matterEarthworms ingest soil and litter and mix organic with mineral material: uses Clay mineralsEarthworms ingest soil and litter and mix organic with mineral material: uses up Plant litteruses upGut passage and mucus bind particles into water-stable casts: makes Soil aggregatesmakesBurrows form biopores that raise infiltration and root access: makes Pore spacemakesAnts and termites build galleries and mounds, moving subsoil upward: makes Pore spacemakesAnts and termites build galleries and mounds, moving subsoil upward: uses Clay mineralsBurrowing mammals and tree-throw create pit-and-mound mixing: uses Soil organic matterNet effect on structure depends on species, soil and management: uses Soil aggregatesStructure improved: stable casts, interconnected pores, mixed organic matter: makes Soil aggregatesmakesStructure improved: stable casts, interconnected pores, mixed organic matter: makes Pore spacemakesmixed with mineral soilSoil organic matter: mixed with mineral soilmixed into organicmaterialClay minerals: mixed into organic materialingested with soilPlant litter: ingested with soilbound into water-stablecastsSoil aggregates: bound into water-stable castsforms biopores forinfiltrationPore space: forms biopores for infiltrationleft as galleries andtunnelsPore space: left as galleries and tunnelscarried upward in moundsClay minerals: carried upward in moundsmixed by mammal andtree-throwSoil organic matter: mixed by mammal and tree-throwaltered by species andmanagementSoil aggregates: altered by species and managementstabilised by casts andorganicsSoil aggregates: stabilised by casts and organicsforms interconnectedpore networkPore space: forms interconnected pore networkStart: Bioturbation:fauna remodel soilstructureSTARTStart: Bioturbation: fauna remodel soil structureEnd: Bioturbation:fauna remodel soilstructureENDEnd: Bioturbation: fauna remodel soil structureEarthworms ingest soiland litter and mixorganic with miner…👍1📄1 ↗1Earthworms ingest soil and litter and mix organic with mineral materialGut passage and mucusbind particles intowater-stable casts📄1Gut passage and mucus bind particles into water-stable castsBurrows form bioporesthat raise infiltrationand root access📄1Burrows form biopores that raise infiltration and root accessAnts and termites buildgalleries and mounds,moving subsoil upward📄1Ants and termites build galleries and mounds, moving subsoil upwardBurrowing mammals andtree-throw createpit-and-mound mixing📄1Burrowing mammals and tree-throw create pit-and-mound mixingNet effect on structuredepends on species,soil and management📄1Net effect on structure depends on species, soil and managementStructure improved:stable casts,interconnected pore…📄1Structure improved: stable casts, interconnected pores, mixed organic matter
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

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

Earthworms ingest soil and litter and mix organic with mineral material
EarthwormsPlant litterSoil organic matterClay minerals
Evidence (1) · added by Fern
  • Lee 1985, Earthworms: Their Ecology and Relationships with Soils and Land Use (Academic Press): Annual cast production is reported over a wide range, about 2 to 250 tonnes per hectare. (confidence 0.6)
Gut passage and mucus bind particles into water-stable casts
EarthwormsGut microbesSoil aggregatesPolysaccharides
Evidence (1) · added by Fern
  • Six, Bossuyt, Degryze & Denef 2004, Soil and Tillage Research 79:7: Reviews that casts are stable aggregates with organic matter protected inside. (confidence 0.7)
Burrows form biopores that raise infiltration and root access
EarthwormsPlant rootsPore spaceWater
Evidence (1) · added by Fern
  • Blouin et al. 2013, European Journal of Soil Science 64:161: Earthworm presence increases infiltration and aeration via burrow networks. (confidence 0.7)
Ants and termites build galleries and mounds, moving subsoil upward
AntsTermitesClay mineralsPore space
Evidence (1) · added by Fern
  • Jouquet et al. 2011, European Journal of Soil Biology 47:215: Termites alter soil texture and porosity and concentrate clay and nutrients in mounds and galleries. (confidence 0.65)
Burrowing mammals and tree-throw create pit-and-mound mixing
Burrowing mammalsTreesSoil organic matter
Evidence (1) · added by Fern
  • Gabet, Reichman & Seabloom 2003, Annual Review of Earth and Planetary Sciences 31:249: Bioturbation by burrowers and tree throw drives soil turnover and sediment transport. (confidence 0.7)
⑂ Net effect on structure depends on species, soil and management
Soil faunaTillageSoil aggregates
Evidence (1) · added by Fern
  • Bohlen et al. 2004, Frontiers in Ecology and the Environment 2:427: Invasive earthworms in North American forests removed the litter layer, showing that effects can be negative. Shares are estimates (+-15 points). (confidence 0.4)
Structure improved: stable casts, interconnected pores, mixed organic matter
Soil aggregatesSoil poresSoil aggregatesPore space
Evidence (1) · added by Fern
  • Van Groenigen et al. 2014, Agriculture, Ecosystems and Environment: Meta-analysis found earthworm presence raised crop yield by about 25% and aboveground biomass by about 23%. (confidence 0.6)