Evaluation of simulated ozone effects in forest ecosystems against biomass damage estimates from fumigation experiments

Abstract

Abstract. Regional estimates of the effects of ozone pollution on forest growth depend on the availability of reliable injury functions that estimate a representative ecosystem response to ozone exposure. A number of such injury functions for forest tree species and forest functional types have recently been published and subsequently applied in terrestrial biosphere models to estimate regional or global effects of ozone on forest tree productivity and carbon storage in the living plant biomass. The resulting impacts estimated by these biosphere models show large uncertainty in the magnitude of ozone effects predicted. To understand the role that these injury functions play in determining the variability in estimated ozone impacts, we use the O-CN biosphere model to provide a standardised modelling framework. We test four published injury functions describing the leaf-level, photosynthetic response to ozone exposure (targeting the maximum carboxylation capacity of Rubisco (Vcmax) or net photosynthesis) in terms of their simulated whole-tree biomass responses against data from 23 ozone filtration/fumigation experiments conducted with young trees from European tree species at sites across Europe with a range of climatic conditions. Our results show that none of these previously published injury functions lead to simulated whole-tree biomass reductions in agreement with the observed dose–response relationships derived from these field experiments and instead lead to significant over- or underestimations of the ozone effect. By re-parameterising these photosynthetically based injury functions, we develop linear, plant-functional-type-specific dose–response relationships, which provide accurate simulations of the observed whole-tree biomass response across these 23 experiments.

What Are the Principal Factors Affecting Ambient Ozone Concentrations in Czech Mountain Forests?

“…On a long-term basis, ambient O 3 has been considered as a stress factor contributing to impairment of forest health status and its influence has been studied from different aspects. In spite of clear evidence of O 3 harmful effects observed in laboratory experiments, fumigation chambers, or FO 3 X (Free air O 3 eXposure) experiments (Sandermann et al, 1997;Paoletti et al, 2017;Franz et al, 2018;Hoshika et al, 2018), the field evidence for impacts of O 3 exposure on tree growth is not that clear (De Vries et al, 2014;Cailleret et al, 2018). Moreover, observations in real stand conditions from numerous regions show that measured high O 3 exposures or modeled high O 3 stomatal flux do not correspond with unclear impacts on forest ecosystems (e.g., Ferretti et al, 2007;Matyssek et al, 2007;Waldner et al, 2007;Baumgarten et al, 2009).…”

Competing effects of nitrogen deposition and ozone exposure on Northern hemispheric terrestrial carbon uptake and storage, 1850–2099

“…Simulations are conducted with the O-CN terrestrial biosphere model Franz et al, 2017), version tun V C where ozone damage is calculated based on injury functions to the maximum carboxylation capacity of the leaf V cmax (Franz et al, 2018). The tun V C injury functions were calibrated to reproduce observed biomass damage relationships of experiments with a range of European tree species in fumigation/filtration experiments (Franz et al, 2018). Contrary to Franz et al (2018), the ozone deposition scheme described in Franz et al (2017) is applied in the simulations here (D-model version in Franz et al (2017)).…”

“…We employ a significantly enhanced version of the O-CN terrestrial biosphere model , which explicitly accounts for the O 3 transport and deposition from the free atmosphere into the stomates, as well as ozone uptake by other processes (such as soil and leaf surface uptake) (Franz et al, 2017). This model has been evaluated against biomass damage relationships observed in a range of fumigation/filtration experiments with European tree species (Büker et al, 2015;Franz et al, 2018).…”

Interactions between Air Pollution and Terrestrial Ecosystems: Perspectives on Challenges and Future Directions

“…Current regional-to-global scale models have large uncertainties and deficiencies in representing key parts of air pollution-ecosystem interactions (IPCC, 2013;Dentener et al, 2006;Fowler et al, 2009;Hudman et al, 2012;Grote et al, 2014;Hardacre et al, 2015;Vivanco et al, 2018;Franz et al, 2018), including plant physiology, leaf biomass, soil properties, emission and 15 can represent changes with human activities and climate, or over ecosystems and regions where there is not a lot of data. Together with process modeling and laboratory or chamber experiments, field measurements can provide constraints on some key uncertain processes, hence facilitating the improvement of current model parameterizations related to air pollution-ecosystem interactions.…”