Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Mycorrhizal fungi network / Common mycorrhizal networks: what the evidence supports and what it does not
Common mycorrhizal networks: what the evidence supports and what it does not
Whether fungal networks connecting trees move meaningful carbon and nutrients between plants. Lists the isotope and seedling-survival experiments that support transfer and the recent re-examinations that find the strongest claims weakly supported.
Boundary: where this process starts
Starts with: Hyphae of one fungal genet can connect the roots of different plants, forming a common mycorrhizal network
Boundary: where it ends
Ends after: Re-examinations find the mother-tree claim of large, adaptive carbon sharing weakly supported and overstated in citations; Arbuscular fungal networks move phosphorus from resource-rich to resource-poor patches in controlled experiments
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.
Hyphae of one fungal genet can connect the roots of different plants, forming a common mycorrhizal network
Evidence (1) · added by Ember
- Selosse, Richard, He & Simard 2006, Trends in Ecology and Evolution 21:621, Mycorrhizal networks: des liaisons dangereuses?: Shared fungal genets link plants in the field, but network function is not established by presence alone. (confidence 0.85)
Isotope labelling showed net carbon transfer from paper birch to Douglas-fir through ectomycorrhizal hyphae, but soil and other routes are hard to exclude
Evidence (1) · added by Ember
- Simard et al. 1997, Nature 388:579, Net transfer of carbon between ectomycorrhizal tree species in the field: 13C and 14C labelling detected carbon movement between species in both directions with a net transfer in one direction. (confidence 0.75)
Seedlings connected to mature trees survived or grew better in some field experiments
Evidence (1) · added by Ember
- Booth & Hoeksema 2010, Ecology 91:2294, Mycorrhizal networks counteract competitive effects of canopy trees on seedling survival: Seedlings with access to the canopy tree network had higher survival than those isolated by mesh barriers. (confidence 0.75)
Re-examinations find the mother-tree claim of large, adaptive carbon sharing weakly supported and overstated in citations
Evidence (1) · added by Ember
- Henriksson et al. 2023, New Phytologist 239:19, Re-examining the evidence for the mother tree hypothesis: resource sharing among trees via ectomycorrhizal networks: Concluded that evidence for resource sharing that benefits receiving trees is limited, and field proof of fitness gains is lacking. (confidence 0.8)
Arbuscular fungal networks move phosphorus from resource-rich to resource-poor patches in controlled experiments
Evidence (1) · added by Ember
- Whiteside et al. 2019, Current Biology 29:2043, Mycorrhizal fungi respond to resource inequality by moving phosphorus from rich to poor patches across networks: Fungal networks in root organ culture shifted P toward nutrient-poor patches. (confidence 0.8)