Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Primary production / Belowground carbon allocation to roots and mycorrhizal fungi
Belowground carbon allocation to roots and mycorrhizal fungi
Part of net primary production goes to roots and arbuscular mycorrhizal fungi as a carbon payment for nutrient uptake, and this cost shrinks when nutrients are abundant.
Boundary: where this process starts
Starts with: Photosynthate is translocated to roots and fungal partner
Boundary: where it ends
Ends after: Root-derived carbon enters the soil food web
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.
Photosynthate is translocated to roots and fungal partner
Evidence (1) · added by Verity
- Douds 1988, Carbon cost of the fungal symbiont relative to net leaf P accumulation in a split-root VA mycorrhizal symbiosis, Plant Physiology, doi:10.1104/pp.86.2.491: In citrus split-root plants 3 to 4% of recently labelled photosynthate went to metabolism of the mycorrhiza in each colonized root half. (confidence 0.8)
Fungal hyphae deliver phosphorus to the plant
Evidence (1) · added by Verity
- Ven 2019, Experimental evidence that phosphorus fertilization and arbuscular mycorrhizal symbiosis can reduce the carbon cost of phosphorus uptake, Functional Ecology, doi:10.1111/1365-2435.13452: AMF-inoculated maize were compared with pasteurized-soil plants to measure the carbon cost of P uptake. (confidence 0.7)
⑂ Phosphorus availability sets the carbon cost of nutrient uptake
Evidence (1) · added by Verity
- Ven 2019, Experimental evidence that phosphorus fertilization and arbuscular mycorrhizal symbiosis can reduce the carbon cost of phosphorus uptake, Functional Ecology, doi:10.1111/1365-2435.13452: P fertilization tended to reduce belowground carbon investment; branch shares are rough estimates. (confidence 0.4)
P-poor soil: high belowground allocation and carbon cost
Evidence (1) · added by Verity
- Ven 2019, Experimental evidence that phosphorus fertilization and arbuscular mycorrhizal symbiosis can reduce the carbon cost of phosphorus uptake, Functional Ecology, doi:10.1111/1365-2435.13452: Increasing nutrient availability typically reduces C investment in root growth and mycorrhizal fungi, so low availability raises it. (confidence 0.75)
P-rich soil: low belowground allocation and carbon cost
Evidence (1) · added by Verity
- Ven 2019, Experimental evidence that phosphorus fertilization and arbuscular mycorrhizal symbiosis can reduce the carbon cost of phosphorus uptake, Functional Ecology, doi:10.1111/1365-2435.13452: P fertilization reduced the carbon cost of P uptake in Zea mays. (confidence 0.75)
Root-derived carbon enters the soil food web
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: A 13C pulse from sugar maple roots reached earthworms, weevils, ants and litter-layer predators, showing the root channel supplies soil heterotroph energy. (confidence 0.8)