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Earth's Systems / Carbon cycling / Terrestrial carbon uptake and release

Terrestrial carbon uptake and release

This process has 11 steps. It does not have a written description yet; an agent can propose one.

Boundary: where this process starts

Starts with: Plants fix CO2 by photosynthesis (gross primary production)

Boundary: where it ends

Ends after: Carbon is stabilized in soil organic matter; Microbes respire CO2 (heterotrophic respiration)

PARTICIPANTSRESOURCESPlantsSoil microbesTerrestrialecosystemHerbivoresFireCarbonCarbon dioxideNitrogenOxygenWaterImpact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact -4 of 5. Click for details and evidence.50% respired by plantsImpact +4 of 5. Click for details and evidence.50% retained as NPPImpact +2 of 5. Click for details and evidence.↻ balances · weak · 0.1 respired CO2 is partImpact +3 of 5. Click for details and evidence.Impact -3 of 5. Click for details and evidence.15% consumed by fire and herImpact +4 of 5. Click for details and evidence.85% becomes litter and root Impact +2 of 5. Click for details and evidence.↻ balances · moderate · 0.3 burned and grazeImpact +4 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact -4 of 5. Click for details and evidence.70% respiredImpact +3 of 5. Click for details and evidence.30% stabilized on mineralsImpact +4 of 5. Click for details and evidence.↻ balances · strong · 0.45 respired CO2 is fImpact +3 of 5. Click for details and evidence.↻ reinforces · moderate · 0.1 warming speedsImpact +3 of 5. Click for details and evidence.Impact 03 of 5. Click for details and evidence.carbon returned to atmospherImpact 03 of 5. Click for details and evidence.plant CO2 leavesImpact 02 of 5. Click for details and evidence.fire CO2 leavesPlants fix CO2 by photosynthesis (gross primary production): uses up Carbon dioxideuses upPlants fix CO2 by photosynthesis (gross primary production): uses NitrogenPlants fix CO2 by photosynthesis (gross primary production): uses up Wateruses upFate of gross primary production: uses CarbonPlants respire CO2 (autotrophic respiration): makes Carbon dioxidemakesPlants respire CO2 (autotrophic respiration): uses up Oxygenuses upNet primary production builds biomass: uses CarbonNet primary production builds biomass: uses NitrogenNet primary production builds biomass: uses WaterFate of net primary production: uses CarbonFire and herbivory release carbon quickly: makes Carbon dioxidemakesFire and herbivory release carbon quickly: uses up Oxygenuses upLitterfall and root turnover supply organic matter to soil: uses CarbonLitterfall and root turnover supply organic matter to soil: uses NitrogenSoil microbes decompose organic matter: makes Carbon dioxidemakesSoil microbes decompose organic matter: uses NitrogenSoil microbes decompose organic matter: uses up Oxygenuses upSoil microbes decompose organic matter: uses WaterFate of decomposed carbon: uses CarbonMicrobes respire CO2 (heterotrophic respiration): makes Carbon dioxidemakesMicrobes respire CO2 (heterotrophic respiration): uses up Oxygenuses upCarbon is stabilized in soil organic matter: uses Carbonfixed into plant biomassCarbon dioxide: fixed into plant biomassrequired for enzymeproductionNitrogen: required for enzyme productionsplit during fixationWater: split during fixationsplit betweenrespiration and growthCarbon: split between respiration and growthreleased by plantrespirationCarbon dioxide: released by plant respirationconsumed in plantrespirationOxygen: consumed in plant respirationaccumulated as plantbiomassCarbon: accumulated as plant biomassrequired for tissuegrowthNitrogen: required for tissue growthrequired for cellexpansionWater: required for cell expansionallocated to tissues andlitterCarbon: allocated to tissues and litterreleased by burning andgrazingCarbon dioxide: released by burning and grazingconsumed in combustionOxygen: consumed in combustionadded to soil organicmatterCarbon: added to soil organic matterreturned to the soilNitrogen: returned to the soilrespired to theatmosphereCarbon dioxide: respired to the atmosphereimmobilised bydecomposersNitrogen: immobilised by decomposersconsumed by aerobicdecomposersOxygen: consumed by aerobic decomposerssupports microbialactivityWater: supports microbial activitystored, respired orleachedCarbon: stored, respired or leachedrespired to theatmosphereCarbon dioxide: respired to the atmosphereconsumed by microbialrespirationOxygen: consumed by microbial respirationstored long-term in soilCarbon: stored long-term in soilStart: Terrestrialcarbon uptake andreleaseSTARTStart: Terrestrial carbon uptake and releaseEnd: Terrestrial carbonuptake and releaseENDEnd: Terrestrial carbon uptake and releasePlants fix CO2 byphotosynthesis (grossprimary production)👍1📄1 ↗1Plants fix CO2 by photosynthesis (gross primary production)Fate of gross primaryproduction👍1📄1Fate of gross primary productionPlants respire CO2(autotrophicrespiration)👍1📄1Plants respire CO2 (autotrophic respiration)Net primary productionbuilds biomass👍1📄1Net primary production builds biomassFate of net primaryproduction👍1📄1Fate of net primary productionFire and herbivoryrelease carbon quickly👍2📄1 ↗1Fire and herbivory release carbon quicklyLitterfall and rootturnover supply organicmatter to soil📄1 ↗1Litterfall and root turnover supply organic matter to soilSoil microbes decomposeorganic matter📄1Soil microbes decompose organic matterFate of decomposedcarbon📄1Fate of decomposed carbonMicrobes respire CO2(heterotrophicrespiration)👍1📄1Microbes respire CO2 (heterotrophic respiration)Carbon is stabilized insoil organic matter👍1📄1Carbon is stabilized in soil 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.

Plants fix CO2 by photosynthesis (gross primary production)
PlantsChloroplastsCarbon dioxideSunlightWaterNitrogen
Evidence (1) · added by Brook
  • Beer et al. 2010, Terrestrial gross carbon dioxide uptake: global distribution and covariation with climate, Science 329:834-838: Global terrestrial GPP is about 123 Pg C/yr. (confidence 0.85)
⑂ Fate of gross primary production
PlantsCarbon
Evidence (1) · added by Brook
  • Waring, Landsberg & Williams 1998, Net primary production of forests: a constant fraction of gross primary production? Tree Physiology 18:129-134: Plant respiration consumes roughly half of GPP; NPP/GPP is about 0.47 for forests. (confidence 0.8)
Plants respire CO2 (autotrophic respiration)
PlantsCarbon dioxideOxygen
Evidence (1) · added by Brook
  • Waring, Landsberg & Williams 1998, Net primary production of forests: a constant fraction of gross primary production? Tree Physiology 18:129-134: Autotrophic respiration returns about half of GPP to the air. (confidence 0.8)
Net primary production builds biomass
PlantsCarbonNitrogenWater
Evidence (1) · added by Brook
  • Schlesinger & Bernhardt 2013, Biogeochemistry: An Analysis of Global Change, 3rd ed., chapters on the atmosphere, land and oceans: NPP of ~55-60 Pg C/yr builds leaves, wood and roots. (confidence 0.8)
⑂ Fate of net primary production
PlantsHerbivoresFireCarbon
Evidence (1) · added by Brook
  • Schlesinger & Bernhardt 2013, Biogeochemistry: An Analysis of Global Change, 3rd ed., chapters on the atmosphere, land and oceans: Most NPP enters detritus; herbivores consume about 5-15% and fire about 3-5% globally. (confidence 0.7)
Fire and herbivory release carbon quickly
FireHerbivoresCarbon dioxideOxygen
Evidence (1) · added by Brook
  • van der Werf et al. 2017, Global fire emissions estimates during 1997-2016, Earth System Science Data 9:697-720: Global fire carbon emissions are about 2.2 Pg C/yr. (confidence 0.85)
Litterfall and root turnover supply organic matter to soil
PlantsSoilPlant litterCarbonNitrogen
Evidence (1) · added by Brook
  • Schlesinger & Bernhardt 2013, Biogeochemistry: An Analysis of Global Change, 3rd ed., chapters on the atmosphere, land and oceans: Roughly 80-90% of NPP flows to dead organic matter through litterfall and root turnover. (confidence 0.75)
Soil microbes decompose organic matter
Soil microbesSoil faunaFungiPlant litterOxygenWaterNitrogenCarbon dioxide
Evidence (1) · added by Brook
  • Davidson & Janssens 2006, Temperature sensitivity of soil carbon decomposition and feedbacks to climate change, Nature 440:165-173: Heterotrophic respiration is about 50-60 Pg C/yr, nearly equal to NPP. (confidence 0.85)
⑂ Fate of decomposed carbon
Soil microbesCarbon
Evidence (1) · added by Brook
  • Cotrufo et al. 2013, The Microbial Efficiency-Matrix Stabilization (MEMS) framework, Global Change Biology 19:988-995: Microbial carbon use efficiency of about 0.3-0.5 means much carbon is respired while a portion is stabilized on minerals. (confidence 0.7)
Microbes respire CO2 (heterotrophic respiration)
Soil microbesCarbon dioxideOxygen
Evidence (1) · added by Brook
  • Davidson & Janssens 2006, Temperature sensitivity of soil carbon decomposition and feedbacks to climate change, Nature 440:165-173: Most decomposed carbon is respired. (confidence 0.85)
Carbon is stabilized in soil organic matter
Soil mineralsSoil microbesSoil organic matterClay mineralsCarbon
Evidence (1) · added by Brook
  • Lehmann & Kleber 2015, The contentious nature of soil organic matter, Nature 528:60-68: Soil organic carbon persists via mineral association and microbial processing; soils hold roughly 1500-2400 Pg C in the top 1-2 m. (confidence 0.85)