Where does the carbon go? A model-data intercomparison of vegetation carbon allocation and turnover processes at two temperate forest free-air CO2 enrichment sites
Author(s)
Type
Journal Article
Abstract
Elevated atmospheric CO
2
concentration (eCO
2
) has the potential to increase vegetation
carbon storage if increased net primary production causes increased long-lived biomass.
Model predictions of eCO
2
effects on vegetation carbon storage depend on how allocation
and turnover processes are represented.
We used data from two temperate forest free-air CO
2
enrichment (FACE) experiments to
evaluate representations of allocation and turnover in 11 ecosystem models.
Observed eCO
2
effects on allocation were dynamic. Allocation schemes based on func-
tional relationships among biomass fractions that vary with resource availability were best able
to capture the general features of the observations. Allocation schemes based on constant
fractions or resource limitations performed less well, with some models having unintended
outcomes. Few models represent turnover processes mechanistically and there was wide vari-
ation in predictions of tissue lifespan. Consequently, models did not perform well at predicting
eCO
2
effects on vegetation carbon storage.
Our recommendations to reduce uncertainty include: use of allocation schemes constrained
by biomass fractions; careful testing of allocation schemes; and synthesis of allocation and
turnover data in terms of model parameters. Data from intensively studied ecosystem manip-
ulation experiments are invaluable for constraining models and we recommend that such
experiments should attempt to fully quantify carbon, water and nutrient budgets.
2
concentration (eCO
2
) has the potential to increase vegetation
carbon storage if increased net primary production causes increased long-lived biomass.
Model predictions of eCO
2
effects on vegetation carbon storage depend on how allocation
and turnover processes are represented.
We used data from two temperate forest free-air CO
2
enrichment (FACE) experiments to
evaluate representations of allocation and turnover in 11 ecosystem models.
Observed eCO
2
effects on allocation were dynamic. Allocation schemes based on func-
tional relationships among biomass fractions that vary with resource availability were best able
to capture the general features of the observations. Allocation schemes based on constant
fractions or resource limitations performed less well, with some models having unintended
outcomes. Few models represent turnover processes mechanistically and there was wide vari-
ation in predictions of tissue lifespan. Consequently, models did not perform well at predicting
eCO
2
effects on vegetation carbon storage.
Our recommendations to reduce uncertainty include: use of allocation schemes constrained
by biomass fractions; careful testing of allocation schemes; and synthesis of allocation and
turnover data in terms of model parameters. Data from intensively studied ecosystem manip-
ulation experiments are invaluable for constraining models and we recommend that such
experiments should attempt to fully quantify carbon, water and nutrient budgets.
Date Issued
2014-05-21
Date Acceptance
2014-04-08
Citation
NEW PHYTOLOGIST, 2014, 203 (3), pp.883-899
ISSN
0028-646X
Publisher
WILEY-BLACKWELL
Start Page
883
End Page
899
Journal / Book Title
NEW PHYTOLOGIST
Volume
203
Issue
3
Copyright Statement
© 2014 The Authors New Phytologist ©
2014 New Phytologist Trust. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/3.0/), which permits use,
distribution and reproduction in any medium, provided the original work is properly cited.
2014 New Phytologist Trust. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/3.0/), which permits use,
distribution and reproduction in any medium, provided the original work is properly cited.
Identifier
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Subjects
Science & Technology
Life Sciences & Biomedicine
Plant Sciences
allocation
carbon (C)
climate change
CO2 fertilisation
elevated CO2
free-air CO2 enrichment (FACE)
models
phenology
ELEVATED ATMOSPHERIC CO2
FINE-ROOT PRODUCTION
CLIMATE-CHANGE
DECIDUOUS FOREST
NITROGEN UPTAKE
USE EFFICIENCY
SOIL CARBON
PINE FOREST
DYNAMICS
RESPONSES
Air
Biomass
Carbon
Carbon Dioxide
Computer Simulation
Ecosystem
Forests
Models, Theoretical
Trees
Wood
06 Biological Sciences
07 Agricultural And Veterinary Sciences
Plant Biology & Botany
Publication Status
Published