Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO sub(2) efflux (F sub(Soil)) and on the contribution of litter ...to F sub(Soil) we used rain shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland by reducing annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added super(13)C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO sub(2) efflux (F sub(Litter)). Soil CO sub(2) efflux and the super(13)C/ super(12)C isotope ratio (d super(13)C) of the respired CO sub(2) after litter addition were measured during the growing season 2007. Drought significantly decreased F sub(Soil) in our litter addition experiment by 59% and F sub(Litter) by 81% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO sub(2) release from litter than on the belowground-derived CO sub(2) efflux (F sub(BG), i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO sub(2) induced by the rewetting after prolonged drought, drought also reduced F sub(Soil) and F sub(Litter) during the entire super(13)C measurement period (April to October) by 26% and 37%, respectively. Overall, our findings show that drought decreased F sub(Soil) and altered its seasonality and its sources. Thus, the C balance of temperate grassland soils respond sensitively to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change on ecosystems C balance.
Active non-linear circuits with an inductor as temporary energy storage are used to increase the power output of piezoelectric microgenerators. The losses in parasitic resistances inside these ...circuits cause efficiencies lower than 100%. This paper presents an optimized switching technique which reduces these losses. By means of simplified approximation equations, it can be shown that independently of the system parameters, the improved switching technique has a higher efficiency than the formerly used technique, independently on the system parameters. With the parameters extracted from simulations of a CMOS integrated implementation, the efficiency can be increased by 9%.
Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO2 efflux (FSoil) and on the contribution of litter to FSoil we ...used rain shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland by reducing annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added 13C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO2 efflux (FLitter). Soil CO2 efflux and the 13C/12C isotope ratio (δ13C) of the respired CO2 after litter addition were measured during the growing season 2007. Drought significantly decreased FSoil in our litter addition experiment by 59% and FLitter by 81% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO2 release from litter than on the belowground-derived CO2 efflux (FBG, i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO2 induced by the rewetting after prolonged drought, drought also reduced FSoil and FLitter during the entire 13C measurement period (April to October) by 26% and 37%, respectively. Overall, our findings show that drought decreased FSoil and altered its seasonality and its sources. Thus, the C balance of temperate grassland soils respond sensitively to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change on ecosystems C balance.
Current climate change models predict significant changes in rainfall patterns across Europe. To explore the effect of drought on soil CO2 efflux (FSoil) and on the contribution of litter to FSoil we ...used rain shelters to simulate a summer drought (May to July 2007) in an intensively managed grassland in Switzerland by reducing annual precipitation by around 30% similar to the hot and dry year 2003 in Central Europe. We added 13C-depleted as well as unlabelled grass/clover litter to quantify the litter-derived CO2 efflux (FLitter). Soil CO2 efflux and the 13C/12C isotope ratio (δ13C) of the respired CO2 after litter addition were measured during the growing season 2007. Drought significantly decreased FSoil in our litter addition experiment by 59% and FLitter by 81% during the drought period itself (May to July), indicating that drought had a stronger effect on the CO2 release from litter than on the belowground-derived CO2 efflux (FBG, i.e. soil organic matter (SOM) and root respiration). Despite large bursts in respired CO2 induced by the rewetting after prolonged drought, drought also reduced FSoil and FLitter during the entire 13C measurement period (April to October) by 26% and 37%, respectively. Overall, our findings show that drought decreased FSoil and altered its seasonality and its sources. Thus, the C balance of temperate grassland soils respond sensitively to changes in precipitation, a factor that needs to be considered in regional models predicting the impact of climate change on ecosystems C balance.
In its latest report, the Intergovernmental Panel on Climate Change (IPCC) concludes that global climate change can still be slowed down if greenhouse gas emissions are rapidly and strongly reduced. ...We present a detailed regional CO... budget for the Alpine tourist region of Davos, Switzerland, including emissions and potential sinks. The aim of the study was (1) to estimate the most important CO... sources and sinks, (2) to identify the most efficient reduction measures and (3) to assess the feasibility of different reduction targets. The results show that the emissions due to heating contribute to a proportion of 86.3% to the total budget, which is mainly due to the harsh local climate and the tourism-focused local economy. They also show that the yearly CO... emissions per capita in Davos exceed the Swiss average of 6 tonnes by 25%. The augmentation of the carbon pool through the natural environment compares to 10.3% of the total emissions, and further afforestation of the community forest can contribute to an improvement of the total budget by 2.6%. The reduction aim of -15% until 2015 (compared with 2004), as set by the municipality itself, could be easily reached through better building insulation and the use of renewable energy sources. More ambitious aims, such as a 2000 W-society or CO... neutrality, however, will not be realised without major drawbacks in living standards. (ProQuest: ... denotes formulae/symbols omitted.)
In its latest report, the Intergovernmental Panel on Climate Change (IPCC) concludes that global climate change can still be slowed down if greenhouse gas emissions are rapidly and strongly reduced. ...We present a detailed regional CO
2 budget for the Alpine tourist region of Davos, Switzerland, including emissions and potential sinks. The aim of the study was (1) to estimate the most important CO
2 sources and sinks, (2) to identify the most efficient reduction measures and (3) to assess the feasibility of different reduction targets. The results show that the emissions due to heating contribute to a proportion of 86.3% to the total budget, which is mainly due to the harsh local climate and the tourism-focused local economy. They also show that the yearly CO
2 emissions per capita in Davos exceed the Swiss average of 6 tonnes by 25%. The augmentation of the carbon pool through the natural environment compares to 10.3% of the total emissions, and further afforestation of the community forest can contribute to an improvement of the total budget by 2.6%. The reduction aim of −15% until 2015 (compared with 2004), as set by the municipality itself, could be easily reached through better building insulation and the use of renewable energy sources. More ambitious aims, such as a 2000
W-society or CO
2 neutrality, however, will not be realised without major drawbacks in living standards.
In this study, we investigated the dynamics of dissolved inorganic and organic nitrogen (N) in throughfall, in soil solutions of Gleysols, and in outflows from experimental sub-catchments as well as ...from a headwater catchment in Switzerland. Additionally, we studied the effect of increased N deposition on dissolved N by applying 3 g NH
4NO
3–N m
−2 year
−1 to soil plots and to one of the sub-catchments. Dissolved organic N (DON) was the dominant form of total dissolved N (TDN) in the soil and surface waters. The proportion of DON in TDN increased from the throughfall down to the subsoil, which indicates that the retention of DON was lower than that of inorganic N. Concentrations of DON in the subsoil were higher under reducing than under oxidising conditions. In the soil solution and in the runoff from all catchments, nitrate and DON displayed inverse seasonal patterns with concentrations of NO
3
− being highest in late winter and those of DON being maximal in summer and fall. This difference shows that during periods of increased biological activity, NO
3
− was retained in the forest ecosystem while the production of DON was stimulated. Concentrations of both NO
3
− and DON were negatively correlated with the amount of throughfall. In the outflow of the headwater catchment, however, the concentration–discharge relationship was negative for NO
3
−, but positive for DON. The reason for this difference appeared to be the larger contribution of topsoil water at high flow, which was poor in NO
3
− and rich in DON. Experimentally increasing the N deposition increased NO
3
− leaching significantly, but had no effects on DON leaching and on DON export from the catchments. In conclusion, our results show that the dynamics of dissolved organic and inorganic N are controlled by different factors.
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