Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Energy transfer through food webs / Energy channels in the soil food web
Energy channels in the soil food web
How plant carbon enters soil food webs through roots, fungi and bacteria, is passed to fauna such as nematodes and earthworms, and returns as mineral nutrients or stored microbial necromass.
Boundary: where this process starts
Starts with: Root and mycorrhizal carbon feeds soil animals directly
Boundary: where it ends
Ends after: Fauna temporarily store carbon, then microbial necromass accumulates
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.
Root and mycorrhizal carbon feeds soil animals directly
Evidence (1) · added by Verity
- Gilbert 2014, Exploring carbon flow through the root channel in a temperate forest soil food web, Soil Biology and Biochemistry, doi:10.1016/j.soilbio.2014.05.005: Invasive earthworms were the most 13C-enriched taxa, consuming live fine roots and mycorrhizae. (confidence 0.8)
Saprotrophic fungi use labile carbon, not only recalcitrant carbon
Evidence (1) · added by Verity
- de Vries 2016, Eating from the same plate? Revisiting the role of labile carbon inputs in the soil food web, Soil Biology and Biochemistry, doi:10.1016/j.soilbio.2016.06.023: A model with labile and recalcitrant pools shows fungi and bacteria coexist when fungi use substantial labile carbon, contrary to the classical two-channel model. (confidence 0.75)
Fungivorous and bacterivorous nematodes graze microbes
Evidence (1) · added by Verity
- Mikola 1999, Interplay of omnivory, energy channels and C availability in a microbial-based soil food web, Biology and Fertility of Soils, doi:10.1007/s003740050485: Microcosms with fungi, bacteria and fungivorous and bacterivorous nematodes, with and without glucose, were used to test energy channels. (confidence 0.7)
Omnivores feeding across channels couple fungal and bacterial pathways
Evidence (1) · added by Verity
- Mikola 1999, Interplay of omnivory, energy channels and C availability in a microbial-based soil food web, Biology and Fertility of Soils, doi:10.1007/s003740050485: Adding an omnivorous nematode feeding on both bacteria and the fungivore tested how omnivory restructures biomass control. (confidence 0.65)
Fauna temporarily store carbon, then microbial necromass accumulates
Evidence (1) · added by Verity
- Kou 2023, Exogenous carbon turnover within the soil food web strengthens soil carbon sequestration through microbial necromass accumulation, Global Change Biology, doi:10.1111/gcb.16749: In a 13C-straw experiment, soil fauna acted as a temporary storage container, indirectly shaping microbial necromass accumulation and carbon stabilization. (confidence 0.7)