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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Primary production / Respiratory losses and carbon-use efficiency

Respiratory losses and carbon-use efficiency

How much of gross primary production is respired by leaves, wood and roots, which sets carbon-use efficiency (NPP divided by GPP) and the carbon left for growth.

Boundary: where this process starts

Starts with: Leaf, wood and root respiration burn fixed carbon

Boundary: where it ends

Ends after: Net carbon left for growth (NPP)

PARTICIPANTSRESOURCESPlantsOrganic carbonOxygenImpact -3 of 5. Click for details and evidence.Impact 03 of 5. Click for details and evidence.Impact 03 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.45% Young or leaf-richImpact -3 of 5. Click for details and evidence.55% Old or woodyImpact +4 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 +2 of 5. Click for details and evidence.↻ reinforces · weak · 0.15 Growth adds respiLeaf, wood and root respiration burn fixed carbon: uses up Organic carbonuses upLeaf, wood and root respiration burn fixed carbon: uses up Oxygenuses upCarbon-use efficiency computed as NPP divided by GPP: uses Organic carbonStand age and leaf-to-total mass ratio set CUE: uses Organic carbonYoung stand with high leaf fraction: high CUE: uses Organic carbonOld stand with large woody mass: low CUE: uses Organic carbonNet carbon left for growth (NPP): makes Organic carbonmakesburned by leaf, wood androot respirationOrganic carbon: burned by leaf, wood and root respirationconsumed in respirationOxygen: consumed in respirationfraction kept for growthOrganic carbon: fraction kept for growthpartitioned by stand ageOrganic carbon: partitioned by stand agemostly retained forgrowthOrganic carbon: mostly retained for growthspent maintaining woodymassOrganic carbon: spent maintaining woody massleft over for growthOrganic carbon: left over for growthStart: Respiratorylosses and carbon-useefficiencySTARTStart: Respiratory losses and carbon-use efficiencyEnd: Respiratory lossesand carbon-useefficiencyENDEnd: Respiratory losses and carbon-use efficiencyLeaf, wood and rootrespiration burn fixedcarbon📄1Leaf, wood and root respiration burn fixed carbonCarbon-use efficiencycomputed as NPP dividedby GPP👍1📄1Carbon-use efficiency computed as NPP divided by GPPStand age andleaf-to-total massratio set CUE👍1📄1Stand age and leaf-to-total mass ratio set CUEYoung stand with highleaf fraction: high CUE📄1Young stand with high leaf fraction: high CUEOld stand with largewoody mass: low CUE📄1Old stand with large woody mass: low CUENet carbon left forgrowth (NPP)👍1📄1Net carbon left for growth (NPP)
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)
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Every step, with its evidence

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Leaf, wood and root respiration burn fixed carbon
PlantsOrganic carbonOxygen
Evidence (1) · added by Verity
  • Curtis 2005, Respiratory carbon losses and the carbon-use efficiency of a northern hardwood forest 1999-2003, New Phytologist, doi:10.1111/j.1469-8137.2005.01438.x: In a Michigan forest total respiration averaged 1425 g C per m2 per yr, split 71% soil, 18% leaf and 11% wood (the soil share includes heterotrophs). (confidence 0.8)
Carbon-use efficiency computed as NPP divided by GPP
PlantsOrganic carbon
Evidence (1) · added by Verity
  • DeLucia 2007, Forest carbon use efficiency: is respiration a constant fraction of gross primary production, Global Change Biology, doi:10.1111/j.1365-2486.2007.01365.x: Across 60 data points the NPP-versus-GPP slope was 0.53 while CUE ranged 0.23 to 0.83 by forest type. (confidence 0.85)
⑂ Stand age and leaf-to-total mass ratio set CUE
PlantsOrganic carbon
Evidence (1) · added by Verity
  • DeLucia 2007, Forest carbon use efficiency: is respiration a constant fraction of gross primary production, Global Change Biology, doi:10.1111/j.1365-2486.2007.01365.x: CUE decreased with stand age and rose with the leaf-to-total mass ratio; branch shares here are rough estimates. (confidence 0.4)
Young stand with high leaf fraction: high CUE
PlantsOrganic carbon
Evidence (1) · added by Verity
  • DeLucia 2007, Forest carbon use efficiency: is respiration a constant fraction of gross primary production, Global Change Biology, doi:10.1111/j.1365-2486.2007.01365.x: CUE increased as leaf mass-to-total mass increased and was lower in older stands. (confidence 0.8)
Old stand with large woody mass: low CUE
PlantsOrganic carbon
Evidence (1) · added by Verity
  • DeLucia 2007, Forest carbon use efficiency: is respiration a constant fraction of gross primary production, Global Change Biology, doi:10.1111/j.1365-2486.2007.01365.x: CUE decreased with increasing age; boreal forests had the lowest age-corrected mean CUE. (confidence 0.8)
Net carbon left for growth (NPP)
PlantsOrganic carbon
Evidence (1) · added by Verity
  • Curtis 2005, Respiratory carbon losses and the carbon-use efficiency of a northern hardwood forest 1999-2003, New Phytologist, doi:10.1111/j.1469-8137.2005.01438.x: Ecosystem carbon-use efficiency was 0.42 (biometric) versus 0.54 (meteorological) at the same forest, so NPP depends on how respiration is estimated. (confidence 0.7)