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Have ozone effects on carbon sequestration been overestimated? A new biomass response function for wheat

Pleijel, Håkan LU ; Danielsson, Henrik LU ; Simpson, D. and Mills, G. (2014) In Biogeosciences 11(16). p.4521-4528
Abstract
Elevated levels of tropospheric ozone can significantly impair the growth of crops. The reduced removal of CO2 by plants leads to higher atmospheric concentrations of CO2, enhancing radiative forcing. Ozone effects on economic yield, e. g. the grain yield of wheat (Triticum aestivum L.), are currently used to model effects on radiative forcing. However, changes in grain yield do not necessarily reflect changes in total biomass. Based on an analysis of 22 ozone exposure experiments with field-grown wheat, we investigated whether the use of effects on grain yield as a proxy for effects on biomass under-or overestimates effects on biomass. First, we confirmed that effects on partitioning and biomass loss are both of significant importance for... (More)
Elevated levels of tropospheric ozone can significantly impair the growth of crops. The reduced removal of CO2 by plants leads to higher atmospheric concentrations of CO2, enhancing radiative forcing. Ozone effects on economic yield, e. g. the grain yield of wheat (Triticum aestivum L.), are currently used to model effects on radiative forcing. However, changes in grain yield do not necessarily reflect changes in total biomass. Based on an analysis of 22 ozone exposure experiments with field-grown wheat, we investigated whether the use of effects on grain yield as a proxy for effects on biomass under-or overestimates effects on biomass. First, we confirmed that effects on partitioning and biomass loss are both of significant importance for wheat yield loss. Then we derived ozone dose response functions for biomass loss and for harvest index (the proportion of above-ground biomass converted to grain) based on 12 experiments and recently developed ozone uptake modelling for wheat. Finally, we used a European-scale chemical transport model (EMEP MSC-West) to assess the effect of ozone on biomass (-9%) and grain yield (-14%) loss over Europe. Based on yield data per grid square, we estimated above-ground biomass losses due to ozone in 2000 in Europe, totalling 22.2 million tonnes. Incorrectly applying the grain yield response function to model effects on biomass instead of the biomass response function of this paper would have indicated total above-ground biomass losses totalling 38.1 million (i.e. overestimating effects by 15.9 million tonnes). A key conclusion from our study is that future assessments of ozone-induced loss of agroecosystem carbon storage should use response functions for biomass, such as that provided in this paper, not grain yield, to avoid overestimation of the indirect radiative forcing from ozone effects on crop biomass accumulation. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Biogeosciences
volume
11
issue
16
pages
4521 - 4528
publisher
Copernicus Publications
external identifiers
  • scopus:84906960107
ISSN
1726-4189
DOI
10.5194/bg-11-4521-2014
project
MERGE
language
English
LU publication?
no
id
c860ad68-9ff4-4dec-9ef7-3d2e25b7cf70 (old id 4862573)
date added to LUP
2014-12-15 10:14:21
date last changed
2017-09-03 03:19:14
@article{c860ad68-9ff4-4dec-9ef7-3d2e25b7cf70,
  abstract     = {Elevated levels of tropospheric ozone can significantly impair the growth of crops. The reduced removal of CO2 by plants leads to higher atmospheric concentrations of CO2, enhancing radiative forcing. Ozone effects on economic yield, e. g. the grain yield of wheat (Triticum aestivum L.), are currently used to model effects on radiative forcing. However, changes in grain yield do not necessarily reflect changes in total biomass. Based on an analysis of 22 ozone exposure experiments with field-grown wheat, we investigated whether the use of effects on grain yield as a proxy for effects on biomass under-or overestimates effects on biomass. First, we confirmed that effects on partitioning and biomass loss are both of significant importance for wheat yield loss. Then we derived ozone dose response functions for biomass loss and for harvest index (the proportion of above-ground biomass converted to grain) based on 12 experiments and recently developed ozone uptake modelling for wheat. Finally, we used a European-scale chemical transport model (EMEP MSC-West) to assess the effect of ozone on biomass (-9%) and grain yield (-14%) loss over Europe. Based on yield data per grid square, we estimated above-ground biomass losses due to ozone in 2000 in Europe, totalling 22.2 million tonnes. Incorrectly applying the grain yield response function to model effects on biomass instead of the biomass response function of this paper would have indicated total above-ground biomass losses totalling 38.1 million (i.e. overestimating effects by 15.9 million tonnes). A key conclusion from our study is that future assessments of ozone-induced loss of agroecosystem carbon storage should use response functions for biomass, such as that provided in this paper, not grain yield, to avoid overestimation of the indirect radiative forcing from ozone effects on crop biomass accumulation.},
  author       = {Pleijel, Håkan and Danielsson, Henrik and Simpson, D. and Mills, G.},
  issn         = {1726-4189},
  language     = {eng},
  number       = {16},
  pages        = {4521--4528},
  publisher    = {Copernicus Publications},
  series       = {Biogeosciences},
  title        = {Have ozone effects on carbon sequestration been overestimated? A new biomass response function for wheat},
  url          = {http://dx.doi.org/10.5194/bg-11-4521-2014},
  volume       = {11},
  year         = {2014},
}