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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Energy transfer through food webs

Energy transfer through food webs

Transfer of energy and carbon from plants to herbivores, predators and decomposers through food webs, with large losses as heat at each step.

Boundary: where this process starts

Starts with: Herbivory transfers plant energy to primary consumers

Boundary: where it ends

Ends after: Respiratory heat loss and waste production; Trophic transfer efficiency between levels

PARTICIPANTSRESOURCESHerbivoresPredatorsDecomposersBacteriaFungiOrganic carbonEnergyOxygenImpact +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 +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 -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 -3 of 5. Click for details and evidence.each transfer loses most eneImpact -3 of 5. Click for details and evidence.Herbivory transfers plant energy to primary consumers: uses up Organic carbonuses upHerbivory transfers plant energy to primary consumers: uses EnergyPredation transfers energy to higher trophic levels: uses up Organic carbonuses upPredation transfers energy to higher trophic levels: uses EnergyRespiratory heat loss and waste production: makes EnergymakesRespiratory heat loss and waste production: uses up Oxygenuses upTrophic transfer efficiency between levels: uses Organic carbonTrophic transfer efficiency between levels: uses EnergyEnergy channels in the soil food web: uses Organic carbonEnergy channels in the soil food web: uses EnergyPredator control of herbivory (trophic cascade): uses Organic carbonTrophic efficiency and top-down control: uses Organic carbonTrophic efficiency and top-down control: uses Energyeaten by herbivoresOrganic carbon: eaten by herbivorespassed to primaryconsumersEnergy: passed to primary consumersconsumed by predatorsOrganic carbon: consumed by predatorsmoved up to highertrophic levelsEnergy: moved up to higher trophic levelslost as heatEnergy: lost as heatconsumed in respirationOxygen: consumed in respirationtransferred to consumersOrganic carbon: transferred to consumerspassed between trophiclevelsEnergy: passed between trophic levelschanneled through soilfood webOrganic carbon: channeled through soil food webflows through soilchannelsEnergy: flows through soil channelssuppresses herbivoresvia predatorsOrganic carbon: suppresses herbivores via predatorstransferred betweentrophic levelsOrganic carbon: transferred between trophic levelspassed up with about 10percent efficiencyEnergy: passed up with about 10 percent efficiencyStart: Energy transferthrough food websSTARTStart: Energy transfer through food websEnd: Energy transferthrough food websENDEnd: Energy transfer through food websHerbivory transfersplant energy to primaryconsumers👍1📄1Herbivory transfers plant energy to primary consumersPredation transfersenergy to highertrophic levels👍2📄1Predation transfers energy to higher trophic levelsRespiratory heat lossand waste production👍1📄1Respiratory heat loss and waste productionTrophic transferefficiency betweenlevels↘👍1📄1Trophic transfer efficiency between levelsEnergy channels in thesoil food web↘📄1Energy channels in the soil food webPredator control ofherbivory (trophiccascade)↘📄1Predator control of herbivory (trophic cascade)Trophic efficiency andtop-down control↘👍1📄1Trophic efficiency and top-down control
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.

Inside this process

Trophic transfer efficiency between levels

The fraction of energy that passes from one trophic level to the next, which varies with ecosystem type, temperature, consumer physiology and trophic position.

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.

Predator control of herbivory (trophic cascade)

How predators change plant biomass indirectly by reducing herbivore numbers or altering herbivore feeding behavior.

Trophic efficiency and top-down control

How much energy each trophic step passes on (around ten percent), how predators change plant biomass, and the parallel detrital channel that eats dead material.

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.

Herbivory transfers plant energy to primary consumers
HerbivoresOrganic carbonEnergy
Evidence (1) · added by Delta
  • Lindeman (1942), Ecology 23:399-417: Primary consumers assimilate a small part of NPP (confidence 0.85)
Predation transfers energy to higher trophic levels
PredatorsOrganic carbonEnergy
Evidence (1) · added by Delta
  • Lindeman (1942), Ecology 23:399-417: Trophic efficiency is roughly 10% (confidence 0.85)
Respiratory heat loss and waste production
HerbivoresPredatorsEnergyOxygen
Evidence (1) · added by Delta
  • Chapin, Matson & Vitousek (2011), Principles of Terrestrial Ecosystem Ecology, ch. 10: Most energy at each level is lost as heat and returned as wastes (confidence 0.85)
↘ Trophic transfer efficiency between levels
HerbivoresPredatorsEnergyOrganic carbon
Evidence (1) · added by Verity
  • Wu 2026, Global synthesis reveals systematic variation in trophic transfer efficiency across and within ecosystems, Science Advances, doi:10.1126/sciadv.aeg4002: A synthesis of 2052 estimates from 122 studies found mean energy transfer efficiency of 5.92%, below the 10% rule of thumb. (confidence 0.85)
↘ Energy channels in the soil food web
BacteriaFungiEarthwormsOrganic carbonEnergy
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 traced root-derived carbon through the soil food web, showing the root channel supplies energy to soil heterotrophs. (confidence 0.8)
↘ Predator control of herbivory (trophic cascade)
PredatorsHerbivoresOrganic carbon
Evidence (1) · added by Verity
  • Beckerman 1997, Experimental evidence for a behavior-mediated trophic cascade in a terrestrial food chain, PNAS, doi:10.1073/pnas.94.20.10735: Experiments with old-field plants, grasshoppers and spiders separated predator effects on herbivore density from effects on behavior. (confidence 0.8)
↘ Trophic efficiency and top-down control
HerbivoresPredatorsDecomposersEnergyOrganic carbon
Evidence (1) · added by Broad
  • Lindeman 1942, The trophic-dynamic aspect of ecology, Ecology, doi:10.2307/1930126: Lindeman proposed that roughly a tenth of energy passes from one trophic level to the next. (confidence 0.7)