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Belyazid S.,Belyazid Consulting and Communication | Kurz D.,EKG Geoscience | Braun S.,Institute For Angewandte Planzenbiologie | Sverdrup H.,Lund University | And 2 more authors.
Environmental Pollution | Year: 2011

A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. © 2010 Elsevier Ltd. All rights reserved. Source

Braun S.,Institute for Applied Plant Biology | Schindler C.,Swiss Tropical and Public Health Institute | Rihm B.,Meteotest
Environmental Pollution | Year: 2014

The estimate of growth losses by ozone exposure of forest trees is a significant part in current C sequestration calculations and will also be important in future modeling. It is therefore important to know if the relationship between ozone flux and growth reduction of young trees, used to derive a Critical Level for ozone, is also valid for mature trees. Epidemiological analysis of stem increment data from Fagus sylvatica L. and Picea abies Karst. observed in Swiss forest plots was used to test this hypothesis. The results confirm the validity of the flux-response relationship at least for beech and therefore enable estimating forest growth losses by ozone on a country-wide scale. For Switzerland, these estimates amount to 19.5% growth reduction for deciduous forests, 6.6% for coniferous forests and 11.0% for all forested areas based on annual ozone stomatal uptake during the time period 1991-2011. © 2014 Elsevier Ltd. All rights reserved. Source

Baumgartner F.P.,ZHAW Zurich University of Applied Sciences | Achtnich T.,ZHAW Zurich University of Applied Sciences | Remund J.,Meteotest | Gnos S.,NET Nowak Energie and Technology AG | Nowak S.,NET Nowak Energie and Technology AG
Progress in Photovoltaics: Research and Applications | Year: 2011

The high growth rate of photovoltaic (PV) installations leads to the question about the consequences for grid integration and management. As a case study, we present an analysis of the first limits for the amount of PV electricity in the utility grid of the greater Zurich area. The first limit is found at an amount of 6% of the yearly electricity generation from PV, where the PV generation capacity begins to exceed the daytime increase of the load profile. This scenario assumes no changes of the daily constant base load generation. If the PV power is further increased to an amount of 10% of the overall electricity generation, about 8% of the PV electricity production could find no demand, starting with a surplus of PV production at noon at sunny weekends in summer time. This would reduce the nominal working hours of the PV plants by 8%, increasing the PV generation costs by the same factor. An amount of 17% of PV generation can be reached in the Zurich utility grid by storing the surplus of unused PV electricity as produced, by the widely available pumped hydro plants in the Swiss Alps. The 17% PV target would also be possible without storage, but it would require reducing the base load power production in favour of PV electricity generation. To further increase the amount of PV electricity generation above 20%, low cost storage means or changes of the load profile would be required. © 2010 John Wiley & Sons, Ltd. Source

Welker C.,University of Bern | Martius O.,University of Bern | Stucki P.,University of Bern | Bresch D.,Swiss Reinsurance Company Ltd | And 2 more authors.
Tellus, Series A: Dynamic Meteorology and Oceanography | Year: 2016

This study investigates the wind gusts and associated economic loss patterns of high-impact winter windstorms in Switzerland between 1871 and 2011. A novel approach for simulating windstorm-related gusts and losses at regional to local scales is applied to a sample of 84 windstorms. The approach involves the dynamical downscaling of the Twentieth Century Reanalysis (20CR) ensemble mean to 3-km horizontal grid size using the Weather Research and Forecasting (WRF) model. Economic losses are simulated at municipal level for present-day asset distribution based on the downscaled (parameterised) wind gusts at high spatiotemporal resolution using the open-source impact model climada.Acomparison with insurance loss data for two recent windstorms ("Lothar" in 1999, "Joachim" in 2011) indicates that the loss simulation allows to realistically simulate the spatial patterns of windstorm losses. The loss amplitude is strongly underestimated for 'Lothar', while it is in reasonable agreement for 'Joachim'. Possible reasons are discussed. Uncertainties concerning the loss simulation arise from the wind gust estimation method applied; estimates can differ considerably among the different methods, in particular over high orography. Furthermore, the quality of the loss simulation is affected by the underlying simplified assumptions regarding the distribution of assets and their susceptibilities to damage. For the whole windstorm sample, composite averages of simulated wind gust speed and loss are computed. Both composites reveal high values for the densely populated Swiss Plateau and lower values for south-eastern Switzerland; metropolitan areas stand out in the loss composite. Eight of the top 10 events concerning the losses simulated for present-day asset distribution and summed over all Swiss municipalities occurred after 1950. It remains uncertain whether this is due to decadal-scale changes of winter windstorms in Switzerland or merely due to a possible bias of the 20CR ensemble mean towards lower wind speeds in the period before around 1950. © 2016 C. Welker et al. Source

Roth T.,Hintermann and Weber AG | Roth T.,University of Basel | Kohli L.,Hintermann and Weber AG | Rihm B.,Meteotest | Achermann B.,Federal Office for the Environment FOEN
Agriculture, Ecosystems and Environment | Year: 2013

Nitrogen (N) deposition is a major threat to biodiversity of many habitats in the lowlands. In mountain habitats, however, the effect of N deposition on biodiversity is not well understood. Here, data from the biodiversity monitoring of Switzerland were used to investigate whether high N deposition is negatively related to species richness and community uniqueness of vascular plants and bryophytes in mountain grassland. The total species diversity, as well as the diversity of three subsets of species (i.e. oligotrophic species, eutrophic species and targeted grassland species according to conservation objectives of the Swiss authorities) were analyzed. Overall, the empirical data from the present study indicate that the currently expert-based range of the critical load of N deposition below which harmful effects on sensitive ecosystems should not occur (upper bound is currently at 20kg Nha-1yr-1) is set too large for mountain hay meadows. Negative relations between N deposition and species richness and community uniqueness in mountain grassland were found already at 10-15kg Nha-1yr-1. The results suggest that the negative effect of N deposition on plant diversity is mainly due to a decrease of oligotrophic plant species and to a lesser extent to an increase in eutrophic plant species. While for bryophytes, the decrease of community uniqueness is related to changes in both oligotrophic and eutrophic species. Furthermore, because plant species richness of target species for conservation was negatively related to N deposition, airborne N deposition is likely to defeat conservation efforts in mountain grassland. © 2013 Elsevier B.V. Source

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