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Contains fulltext : 157118.pdf (publisher's version ) (Closed access)

Contains fulltext : 162039.pdf (publisher's version ) (Closed access)

Contains fulltext : 111393.pdf (preprint version ) (Open Access)

This study derived Species Sensitivity Distributions (SSD), representing a cumulative stressor-response distribution based on single-species sensitivity data, for ozone exposure on natural vegetation. SSDs were constructed for three species groups, i.e. trees, annual grassland and perennial grassland species, using species-specific exposure response data. The SSDs were applied in two ways. First, critical levels were calculated for each species group and compared to current critical levels for ozone exposure. Second, spatially explicit estimates of the potentially affected fraction of plant species in Northwestern Europe were calculated, based on ambient ozone concentrations. We found that the SSD-based critical levels were lower than for the current critical levels for ozone exposure, with conventional critical levels for ozone relating to 8-20% affected plant species. Our study shows that the SSD concept can be successfully applied to both derive critical ozone levels and estimate the potentially affected species fraction of plant communities along specific ozone gradients. (C) 2013 Elsevier Ltd. All rights reserved.

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This paper considers the extent to which indicators of critical load exceedance capture the potential impacts of changes in nitrogen deposition on ecosystem services. It shows that there are significant links between nitrogen deposition and a large range of ecosystem services. There is potential for indicators to be adapted to provide more specific qualitative information for Natura 2000 sites of the implications of critical load exceedance for ecosystem services. For the provision of ecosystems goods (e.g. food, fuel, fibre) and water quality and erosion regulation, it is likely that quite specific information can be provided on the effects of nitrogen deposition. For others, such as pollination and cultural services, the implications for ecosystem services are likely to depend on the specific changes in species composition that are found in specific habitats and sites. The issue of climate regulation has been identified as a critical ecosystem service, but this effect is not currently considered explicitly in setting critical loads, and given the complexity of the potential effects of nitrogen deposition on different greenhouse gas fluxes, it seems impractical to include this in any simple assessment of effects of critical load exceedance. There are ecosystem services where exceedance of the established empirical critical load for nitrogen input can be a positive outcome, for example, increases in more nitrophilous species increasing productivity in certain grassland types and increased grass growth stabilising coastal dunes, and hence enhancing erosion regulation. An ecosystems approach would therefore have value in informing the prioritization of conservation management practices in areas with high nitrogen deposition, depending on the ecosystem service that is most valued at any particular site. However, given that the cause and effect relationships underlying important ecosystem services are often complex and not sufficiently understood, more data and research

Contains fulltext : 72235.pdf (publisher's version ) (Closed access)

A multiplicative and a semi-mechanistic, BWB-type [Ball, J.T., Woodrow, I.E., Berry, J.A., 1987. A model predicting stomatalconductance and its contribution to the control of photosynthesis under different environmental conditions. In: Biggens, J. (Ed.), Progress in Photosynthesis Research, vol. IV. Martinus Nijhoff, Dordrecht, pp. 221–224.] algorithm for calculating stomatalconductance (gs) at the leaf level have been parameterised for two crop and two tree species to test their use in regional scale ozone deposition modelling. The algorithms were tested against measured, site-specific data for durum wheat, grapevine, beech and birch of different European provenances. A direct comparison of both algorithms showed a similar performance in predicting hourly means and daily time-courses of gs, whereas the multiplicative algorithm outperformed the BWB-type algorithm in modelling seasonal time-courses due to the inclusion of a phenology function. The re-parameterisation of the algorithms for local conditions in order to validate ozone deposition modelling on a European scale reveals the higher input requirements of the BWB-type algorithm as compared to the multiplicative algorithm because of the need of the former to model net photosynthesis (An)