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

Pleijel, Håkan; Danielsson, H.; Simpson, David; Mills, Gina

doi:10.5194/bg-11-4521-2014

Cited by 20 publications

(9 citation statements)

References 32 publications

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“…One possible explanation could involve a shift in partitioning of photosynthate among various plant parts, roots, shoots, foliage, etc. (Rennenberg et al 1996;Pleijel et al 2014). Another explanation is that insensitive grasses appear to fill niches left as the level of the clover falls, similar to the report of Gonzalez-Fernandez et al (2008), who found that ryegrass (L. perenne) replaced clover when the two were grown simultaneously under elevated ozone concentrations.…”

Section: Discussionsupporting

confidence: 70%

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Changes in southern Piedmont grassland community structure and nutritive quality with future climate scenarios of elevated tropospheric ozone and altered rainfall patterns

et al. 2015

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Forage species common to the southern USA Piedmont region, Lolium arundinacea, Paspalum dilatatum, Cynodon dactylon and Trifolium repens, were established in a model pasture system to test the future climate change scenario of increasing ozone exposure in combination with varying rainfall amounts on community structure and nutritive quality. Forages were exposed to two levels of ozone [ambient (non-filtered; NF) and twice ambient (2×) concentrations] with three levels of precipitation (average or ±20% of average) in modified open-top chambers (OTCs) from June to September 2009. Dry matter (DM) yield did not differ over the growing season between forage types, except in primary growth grasses where DM yield was higher in 2× than NF treatment. Primary growth clover decreased in nutritive quality in 2× ozone because of increased concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). Re-growth clover exhibited the largest decrease in nutritive quality, whereas grasses were not adversely affected in 2× ozone. Re-growth grasses responded positively to 2× ozone exposure, as indicated in increased relative food value (RFV) and percentage crude protein (CP) than NF-exposed re-growth grasses. Effects of precipitation were not significant over the growing season for primary or re-growth forage, except in primary growth grasses where DM yield was higher in chambers with above average (+20%) precipitation. Total canopy cover was significantly higher over the growing season in chambers receiving above average precipitation, but no significant effects were observed with ozone. Results indicate shifts in plant community structure and functioning related to mammalian herbivore herbivory in future climate change scenarios.

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Section: Discussionsupporting

confidence: 70%

“…; Pleijel et al . ). Another explanation is that insensitive grasses appear to fill niches left as the level of the clover falls, similar to the report of Gonzalez‐Fernandez et al .…”

Section: Discussionmentioning

confidence: 97%

Changes in southern Piedmont grassland community structure and nutritive quality with future climate scenarios of elevated tropospheric ozone and altered rainfall patterns

et al. 2015

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“…Yield losses due to ozone have been ascribed to various yield components in different crops, including reductions in individual seed weight, reduced spikelet number, enhanced spikelet fertility, and reduced panicle or pod number (Ainsworth, 2008;Feng, Kobayashi, & Ainsworth, 2008;Morgan, Ainsworth, & Long, 2003), with associated reductions in harvest index (e.g. for wheat, Pleijel, Danielsson, Simpson, & Mills, 2014). Maintaining high values in these harvest fractions despite ozone stress forms an important breeding target, but synergies or trade-offs with other types of stress would be complex and little information is available to date.…”

Section: Plant Traits Associated With Tolerance Of Ozone and Associmentioning

confidence: 99%

Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance

Mills

Sharps

Simpson

et al. 2018

Global Change Biology

187

142

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Increasing both crop productivity and the tolerance of crops to abiotic and biotic stresses is a major challenge for global food security in our rapidly changing climate. For the first time, we show how the spatial variation and severity of tropospheric ozone effects on yield compare with effects of other stresses on a global scale, and discuss mitigating actions against the negative effects of ozone. We show that the sensitivity to ozone declines in the order soybean > wheat > maize > rice, with genotypic variation in response being most pronounced for soybean and rice. Based on stomatal uptake, we estimate that ozone (mean of 2010-2012) reduces global yield annually by 12.4%, 7.1%, 4.4% and 6.1% for soybean, wheat, rice and maize, respectively (the "ozone yield gaps"), adding up to 227 Tg of lost yield. Our modelling shows that the highest ozone-induced production losses for soybean are in North and South America whilst for wheat they are in India and China, for rice in parts of India, Bangladesh, China and Indonesia, and for maize in China and the United States. Crucially, we also show that the same areas are often also at risk of high losses from pests and diseases, heat stress and to a lesser extent aridity and nutrient stress. In a solution-focussed analysis of these results, we provide a crop ideotype with tolerance of multiple stresses (including ozone) and describe how ozone effects could be included in crop breeding programmes. We also discuss altered crop management approaches that could be applied to reduce ozone impacts in the shorter term. Given the severity of ozone effects on staple food crops in areas of the world that are also challenged by other stresses, we recommend increased attention to the benefits that could be gained from addressing the ozone yield gap.

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“…That sensitivity implies a 20 %-24 % drop in biomass production at FLUXNET crop sites. Some studies have quantified O 3 dose-response relationships with other thresholds Y = 1.6 to 6 nmol O 3 m −2 s −1 (e.g., Karlsson et al, 2007;Pleijel et al, 2004Pleijel et al, , 2014, but the sensitivities have a similar magnitude. Fares et al (2013) also demonstrated 12 %-19 % reduction in gross primary production due to O 3 at some of the same crop and forest FLUXNET sites.…”

Section: W126mentioning

confidence: 99%

Synthetic ozone deposition and stomatal uptake at flux tower sites

et al. 2018

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Abstract. We develop and evaluate a method to estimate O3 deposition and stomatal O3 uptake across networks of eddy covariance flux tower sites where O3 concentrations and O3 fluxes have not been measured. The method combines standard micrometeorological flux measurements, which constrain O3 deposition velocity and stomatal conductance, with a gridded dataset of observed surface O3 concentrations. Measurement errors are propagated through all calculations to quantify O3 flux uncertainties. We evaluate the method at three sites with O3 flux measurements: Harvard Forest, Blodgett Forest, and Hyytiälä Forest. The method reproduces 83 % or more of the variability in daily stomatal uptake at these sites with modest mean bias (21 % or less). At least 95 % of daily average values agree with measurements within a factor of 2 and, according to the error analysis, the residual differences from measured O3 fluxes are consistent with the uncertainty in the underlying measurements. The product, called synthetic O3 flux or SynFlux, includes 43 FLUXNET sites in the United States and 60 sites in Europe, totaling 926 site years of data. This dataset, which is now public, dramatically expands the number and types of sites where O3 fluxes can be used for ecosystem impact studies and evaluation of air quality and climate models. Across these sites, the mean stomatal conductance and O3 deposition velocity is 0.03–1.0 cm s−1. The stomatal O3 flux during the growing season (typically April–September) is 0.5–11.0 nmol O3 m−2 s−1 with a mean of 4.5 nmol O3 m−2 s−1 and the largest fluxes generally occur where stomatal conductance is high, rather than where O3 concentrations are high. The conductance differences across sites can be explained by atmospheric humidity, soil moisture, vegetation type, irrigation, and land management. These stomatal fluxes suggest that ambient O3 degrades biomass production and CO2 sequestration by 20 %–24 % at crop sites, 6 %–29 % at deciduous broadleaf forests, and 4 %–20 % at evergreen needleleaf forests in the United States and Europe.

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

Cited by 20 publications

References 32 publications

Changes in southern Piedmont grassland community structure and nutritive quality with future climate scenarios of elevated tropospheric ozone and altered rainfall patterns

Changes in southern Piedmont grassland community structure and nutritive quality with future climate scenarios of elevated tropospheric ozone and altered rainfall patterns

Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance

Synthetic ozone deposition and stomatal uptake at flux tower sites

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