Developing ozone critical levels for multi-species canopies of Mediterranean annual pastures. (January 2017)

• Record Type: Journal Article
• Authors: Calvete-Sogo, H.; González-Fernández, I.; García-Gómez, H.; Alonso, R.; Elvira, S.; Sanz, J.; Bermejo-Bermejo, V.
• Is Part Of: Environmental pollution. Volume 220:Part A(2017)
• Page Start: 186
• Page End: 195
• Publication Date: 2017-01
• Subjects: Ozone and nitrogen interaction -- Dehesa pasture -- Stomatal conductance -- Phytotoxic ozone dose -- AOT40; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2016.09.038
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Ozone (O3 ) critical levels (CLe) are still poorly developed for herbaceous vegetation. They are currently based on single species responses which do not reflect the multi-species nature of semi-natural vegetation communities. Also, the potential effects of other factors like the nitrogen (N) input are not considered in their derivation, making their use uncertain under natural conditions. Exposure- and dose-response relationships were derived from two open-top chamber experiments exposing a mixture of 6 representative annual Mediterranean pasture species growing in natural soil to 4 O3 fumigation levels and 3 N inputs. The Deposition of O3 and Stomatal Exchange model (DO3 SE) was modified to account for the multi-species nature of the canopy following a big-leaf approach. This new approach was used for estimating a multi-species phytotoxic O3 dose (PODy-MS ). Response relationships were derived based on O3 exposure (AOT40) and flux (PODy-MS ) indices. The treatment effects were similar in the two seasons: O3 reduced the aboveground biomass growth and N modulated this response. Gas exchange rates presented a high inter-specific variability and important inter-annual fluctuations as a result of varying growing conditions during the two years. The AOT40-based relationships were not statistically significant except when the highest N input was considered alone. In contrast, PODy-MS relationships were all significant but for the lowest N input level. The influence of the N input on the exposure- and dose-response relationships implies that N can modify the O3 CLe. However, this is an aspect that has not been considered so far in the methodologies for establishing O3 CLe. Averaging across N input levels, a multi-species O3 CLe (CLef-MS ) is proposed POD1-MS = 7.9 mmol m −2, accumulated over 1.5 month with a 95% confidence interval of (5.9, 9.8). Further efforts will be needed for comparing the CLef-MS with current O3 CLef based on single species responses. Graphical abstract: Abstract : N input modified the value of a new multi-species level flux-based O3 critical level derived for Mediterranean annual pastures.