Design and performance of a free-air exposure system to study long-term effects of ozone on grasslands

Volk, Matthias; Geissmann, M.; Blatter, A.; Contat, François; Fuhrer, J.

doi:10.1016/s1352-2310(02)01012-9

Cited by 31 publications

(24 citation statements)

References 20 publications

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“…However, experimental results often suffer from artefacts caused by altered microclimatic conditions in field exposure chambers, or results obtained with artificial plant communities are difficult to extrapolate to natural situations (Bassin et al 2007a). To overcome these limitations, recent ozone-exposure studies have used a free-air fumigation technique in mature grassland systems (Volk et al 2003;Bassin et al 2007b). But, as in any manipulative experiment with such systems, processes operating at various spatial and temporal scales can complicate the interpretation of observations.…”

Section: Introductionmentioning

confidence: 99%

Spatial heterogeneity confounded ozone-exposure experiment in semi-natural grassland

Stämpfli

Fuhrer²

2009

Oecologia

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Interpretation of observations from manipulative experiments is often complicated by a multitude of uncontrolled processes operating at various spatial and temporal scales. As such processes may differ among experimental plots there is a risk that effects of experimental treatments are confounded. Here we report on a free-air ozone-exposure experiment in permanent semi-natural grassland that suggested strong ozone effects on community productivity after 5 years. We tested ozone effects and investigated the potential of confounding due to changes in nutrient management. Repeated-measure ANOVA revealed mainly negative temporal trends for frequency of abundant productive plant species. Constrained ordination additionally showed converging trajectories of species compositions for ozone and control treatments with time. Yields sampled prior to the start of the experiment and soil nitrogen concentrations revealed that spatial heterogeneity in the soil nutrient status was not accounted for by the random allocation of treatments to plots with a bias towards less productive patches in the elevated-ozone plots. Re-analysis of yield data using repeated-measure ANOVA with a covariable to account for productivity prior to the start of fumigation revealed effects on the temporal changes in total yield and yield of legumes that cannot be separated between ozone and pre-treatment nutrient status. Changes in species composition favour an ecological interpretation with spatial heterogeneity as the major cause of different yield declines. Although elevated ozone may cause subtle physiological changes with longer term implications, our new results suggest that species-rich mature grassland such as the one studied at Le Mouret may be less sensitive to elevated ozone than previously assumed. In this experiment a confounded design was hidden at the start by transitory effects of a prior change in nutrient treatments.

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Section: Introductionmentioning

confidence: 99%

Spatial heterogeneity confounded ozone-exposure experiment in semi-natural grassland

Stämpfli

Fuhrer²

2009

Oecologia

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“…Open-air field fumigation systems, such as that pioneered for semi-natural vegetation in Switzerland (Volk et al, 2003), appear to be necessary -but the cost of such systems, and the likely need for long-term treatments, means that they need to be used in addressing specific hypotheses that have been derived from more restricted and controlled experiments in chambers. However, the limitations of continued experimentation in controlled chambers must be recognised if progress in understanding is to be made.…”

Section: Discussionmentioning

confidence: 99%

Challenges in Understanding the Risks to Natural and Semi-Natural Vegetation from Ozone Exposure

Cape¹,

Bassin²,

Fuhrer³

et al. 2008

Ital J Agronomy

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SummaryThe effects of tropospheric ozone on crops and forests have been studied intensively, but effects on natural and semi-natural plant communities are poorly understood. This lack of understanding arises partly from a lack of experimental studies of whole mature communities, and the effects of ozone on competition and interactions with climate, nutrition etc., and partly from a lack of knowledge of the factors which predispose individual plant species to ozone damage. A recent review of the effects of ozone on grasslands (Bassin et al., 2007a) has drawn attention to the problems involved; this paper seeks to identify the practical issues that must be addressed in improving our knowledge and thereby identifying the risks associated with ozone exposure. This is a necessary first step before mitigation strategies can be developed.

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“…During the last two decades large-scale FACE-type O 3 exposure systems have been employed in O 3 effects studies with crops like soybean (Morgan et al 2004), rice and wheat , and young tree species (Karnosky et al 1999). A similar custom-designed circular free air O 3 exposure system was used by Volk et al (2003) in a Swiss grassland system. A free air O 3 fumigation system in mature tree crowns of beech and spruce in Germany was developed by Werner and Fabian (2002) and tested and used by Matyssek et al (2010aMatyssek et al ( , b, 2013.…”

Section: Methods To Study Ozone Impactsmentioning

confidence: 99%

“…For example, Nebel and Fuhrer (1994) classified 31 species according to the appearance of visible injury when grown in soil blocks of intact semi-natural grassland vegetation and Evans and Ashmore (1992) showed that during a season with relative high O 3 levels total aboveground biomass of a semi-natural grassland community was decreased. More recently, an old, species-rich (53 species) pasture at a mid-elevation site in Switzerland was exposed for seven years to O 3 in a free air exposure system under real field conditions (Volk et al 2003). For individual growth periods, no relationship between the O 3 exposure level and yield differences was observed.…”

Section: Plant Competition and Community Compositionmentioning

confidence: 99%

Plant-Mediated Ecosystem Effects of Tropospheric Ozone

2014

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Design and performance of a free-air exposure system to study long-term effects of ozone on grasslands

Cited by 31 publications

References 20 publications

Spatial heterogeneity confounded ozone-exposure experiment in semi-natural grassland

Spatial heterogeneity confounded ozone-exposure experiment in semi-natural grassland

Challenges in Understanding the Risks to Natural and Semi-Natural Vegetation from Ozone Exposure

Plant-Mediated Ecosystem Effects of Tropospheric Ozone

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