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Earth's Systems / Nutrient cycling / Biological uptake, litter return and mineralization

Biological uptake, litter return and mineralization

How plants take up nutrients, allocate and resorb them, and return the remainder in litter, followed by decomposition that either mineralizes nutrients for reuse or immobilizes them in microbial biomass.

Boundary: where this process starts

Starts with: Roots and mycorrhizal fungi take up nutrients from soil solution

Boundary: where it ends

Ends after: Net mineralization releases inorganic N and P; Microbes immobilize nutrients in their biomass

PARTICIPANTSRESOURCESPlantsSoil microbesMycorrhizalfungiDecomposersFungiOtherparticipantsNitrogenPhosphorusAmmoniumPhosphateCarbonImpact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.62% resorbedImpact +3 of 5. Click for details and evidence.38% left in litterImpact +3 of 5. Click for details and evidence.↻ reinforces · moderate · 0.5 stored nutrienImpact +4 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.60% net mineralizationImpact -3 of 5. Click for details and evidence.40% net immobilizationImpact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.immobilized nutrients becomeImpact +4 of 5. Click for details and evidence.↻ reinforces · strong · 0.9 released nutrienImpact +3 of 5. Click for details and evidence.temperature and moisture modImpact +3 of 5. Click for details and evidence.Impact 02 of 5. Click for details and evidence.nutrients held in microbial Roots and mycorrhizal fungi take up nutrients from soil solution: uses up Nitrogenuses upRoots and mycorrhizal fungi take up nutrients from soil solution: uses up Phosphorususes upRoots and mycorrhizal fungi take up nutrients from soil solution: uses up Ammoniumuses upRoots and mycorrhizal fungi take up nutrients from soil solution: uses up Phosphateuses upNutrients are allocated to leaves, wood and roots: uses NitrogenNutrients are allocated to leaves, wood and roots: uses PhosphorusNutrients are allocated to leaves, wood and roots: uses CarbonLeaves senesce and plants withdraw nutrients first: uses NitrogenLeaves senesce and plants withdraw nutrients first: uses PhosphorusNutrients are resorbed and stored for the next growth flush: uses NitrogenNutrients are resorbed and stored for the next growth flush: uses PhosphorusRemaining nutrients drop in litter: uses NitrogenRemaining nutrients drop in litter: uses PhosphorusDecomposers break down litter; outcome depends on its carbon to nitrogen ratio: uses NitrogenDecomposers break down litter; outcome depends on its carbon to nitrogen ratio: uses CarbonNet mineralization releases inorganic N and P: makes AmmoniummakesNet mineralization releases inorganic N and P: makes PhosphatemakesMicrobes immobilize nutrients in their biomass: uses up Ammoniumuses upMicrobes immobilize nutrients in their biomass: uses up Phosphateuses upMicrobes immobilize nutrients in their biomass: uses up Carbonuses upMicrobial turnover and grazing release nutrients: makes AmmoniummakesMicrobial turnover and grazing release nutrients: makes Phosphatemakesabsorbed by rootsNitrogen: absorbed by rootsabsorbed by rootsPhosphorus: absorbed by rootsabsorbed by rootsAmmonium: absorbed by rootsabsorbed by rootsPhosphate: absorbed by rootsdistributed to organsNitrogen: distributed to organsdistributed to organsPhosphorus: distributed to organsdistributed withnutrientsCarbon: distributed with nutrientswithdrawn from leavesNitrogen: withdrawn from leaveswithdrawn from leavesPhosphorus: withdrawn from leavesstored for regrowthNitrogen: stored for regrowthstored for regrowthPhosphorus: stored for regrowthlost in litterfallNitrogen: lost in litterfalllost in litterfallPhosphorus: lost in litterfallmineralized orimmobilizedNitrogen: mineralized or immobilizedrespired or retainedCarbon: respired or retainedreleased from organicmatterAmmonium: released from organic matterreleased from organicmatterPhosphate: released from organic mattertaken into microbialbiomassAmmonium: taken into microbial biomasstaken into microbialbiomassPhosphate: taken into microbial biomassbuilt into microbialcellsCarbon: built into microbial cellsreleased from dead cellsAmmonium: released from dead cellsreleased from dead cellsPhosphate: released from dead cellsStart: Biologicaluptake, litter returnand mineralizationSTARTStart: Biological uptake, litter return and mineralizationEnd: Biological uptake,litter return andmineralizationENDEnd: Biological uptake, litter return and mineralizationRoots and mycorrhizalfungi take up nutrientsfrom soil solution📄1 ↗1Roots and mycorrhizal fungi take up nutrients from soil solutionNutrients are allocatedto leaves, wood androots📄1Nutrients are allocated to leaves, wood and rootsLeaves senesce andplants withdrawnutrients first👍1📄1Leaves senesce and plants withdraw nutrients firstNutrients are resorbedand stored for the nextgrowth flush👍1📄1Nutrients are resorbed and stored for the next growth flushRemaining nutrientsdrop in litter👍1📄1Remaining nutrients drop in litterDecomposers break downlitter; outcome dependson its carbon …📄1Decomposers break down litter; outcome depends on its carbon to nitrogen ratioNet mineralizationreleases inorganic Nand P📄1 ↗1Net mineralization releases inorganic N and PMicrobes immobilizenutrients in theirbiomass👍1📄1Microbes immobilize nutrients in their biomassMicrobial turnover andgrazing releasenutrients👍1📄1Microbial turnover and grazing release nutrientsWarming and moisturespeed or slowmineralization📄1Warming and moisture speed or slow mineralization
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.

Roots and mycorrhizal fungi take up nutrients from soil solution
PlantsMycorrhizal fungiNitrogenPhosphorusAmmoniumNitratePhosphateWater
Evidence (1) · added by Brook
  • Brady & Weil 2016, The Nature and Properties of Soils, 15th ed., chapters on nitrogen and sulfur economy and on soil phosphorus: Plant nutrient uptake is by diffusion and mass flow supplemented by mycorrhizal hyphae. (confidence 0.8)
Nutrients are allocated to leaves, wood and roots
PlantsNitrogenPhosphorusCarbon
Evidence (1) · added by Brook
  • Schlesinger & Bernhardt 2013, Biogeochemistry: An Analysis of Global Change, 3rd ed., chapters on the land, wetlands and global nitrogen and phosphorus cycles: Plant tissue stoichiometry is about C:N:P of 800:20:1 in leaves. (confidence 0.6)
⑂ Leaves senesce and plants withdraw nutrients first
PlantsNitrogenPhosphorus
Evidence (1) · added by Brook
  • Vergutz et al. 2012, Global resorption efficiencies of trees and shrubs: nitrogen and phosphorus, Ecological Monographs 82:205-220: Trees resorb about 62% of leaf N and 65% of leaf P before leaf fall. (confidence 0.8)
Nutrients are resorbed and stored for the next growth flush
PlantsNitrogenPhosphorus
Evidence (1) · added by Brook
  • Vergutz et al. 2012, Global resorption efficiencies of trees and shrubs: nitrogen and phosphorus, Ecological Monographs 82:205-220: Resorption lowers dependence on soil supply. (confidence 0.8)
Remaining nutrients drop in litter
PlantsSoilPlant litterNitrogenPhosphorus
Evidence (1) · added by Brook
  • Vergutz et al. 2012, Global resorption efficiencies of trees and shrubs: nitrogen and phosphorus, Ecological Monographs 82:205-220: About a third of leaf N and P stays in litter. (confidence 0.8)
⑂ Decomposers break down litter; outcome depends on its carbon to nitrogen ratio
Soil microbesFungiSoil faunaPlant litterNitrogenCarbon
Evidence (1) · added by Brook
  • Brady & Weil 2016, The Nature and Properties of Soils, 15th ed., chapters on nitrogen and sulfur economy and on soil phosphorus: Net mineralization occurs when litter C:N is below roughly 25 and net immobilization above it. (confidence 0.6)
Net mineralization releases inorganic N and P
Soil microbesAmmoniumPhosphateCarbon dioxide
Evidence (1) · added by Brook
  • Brady & Weil 2016, The Nature and Properties of Soils, 15th ed., chapters on nitrogen and sulfur economy and on soil phosphorus: Excess nutrients beyond microbial demand are released. (confidence 0.8)
Microbes immobilize nutrients in their biomass
Soil microbesFungiAmmoniumNitratePhosphateCarbon
Evidence (1) · added by Brook
  • Brady & Weil 2016, The Nature and Properties of Soils, 15th ed., chapters on nitrogen and sulfur economy and on soil phosphorus: Microbes compete with plants for mineral N when litter is carbon-rich. (confidence 0.8)
Microbial turnover and grazing release nutrients
Soil faunaProtozoaNematodesVirusesMicrobial biomassAmmoniumPhosphate
Evidence (1) · added by Brook
  • Clarholm 1985, Interactions of bacteria, protozoa and plants leading to mineralization of soil nitrogen, Soil Biology and Biochemistry 17:181-187: Protozoan grazing on bacteria (the microbial loop in soil) releases N for plants. (confidence 0.8)
Warming and moisture speed or slow mineralization
ClimateSoil microbesHeatWater
Evidence (1) · added by Brook
  • Davidson & Janssens 2006, Temperature sensitivity of soil carbon decomposition and feedbacks to climate change, Nature 440:165-173: Rates of decomposition and mineralization rise with temperature and are highest at intermediate moisture. (confidence 0.7)