Coping with variability and change: Floods and droughts

Floods and droughts are natural phenomena for which the risks of occurrence are likely to continue to grow. Increasing levels of exposure and insufficient adaptive capacity are among the factors responsible for the rising vulnerability. The former is conditioned by anthropopressure (e.g., economic development of flood–prone areas) and adverse effects of climate change; scenarios for future climates indicate the possibility of amplified water–related extremes. This article presents the current situation of coping with extreme hydrological events within the pressure–state–response framework. Among promising response strategies, the role of forecast and warning, and of watershed management are reviewed. Sample success stories and lessons learnt related to hydrological extremes are given and policy implications discussed.     

Phonotaxis during walking and flight: are differences in selectivity due to predation pressure?

Female selectivity was tested in Tettigonia viridissima during two different phonotaxis situations; compensated walking and tethered flight. For two of the three temporal parameters that are important for call recognition in T. viridissima, selectivity was similar in the two situations. Selectivity for the third parameter (minimum interval duration between the double pulses) was much higher during walking than during flight: walking females responded only to stimuli with intervals of 28 ms or longer, while call models with intervals of 18 ms were attractive during flight. One interneuron (TN-1) is probably involved in filtering the minimum interval duration. As this neuron is also the most likely candidate for transmitting bat calls during flight, it is suggested that the selectivity differences between walking and flying might be due to the need for detecting predator signals during flight, when TN-1 would be occupied listening for bats. With TN-1 unavailable for song processing during flight, temporal selectivity for the minimum interval duration should be reduced, as was found here.     

Status of PCDD/F-emission control in Germany on the basis of the current legislation and strategies for further action

The protection of environment from polychlorinated dibenzodioxin and -furan (PCDD/F) impacts, caused by a heterogeneous spectrum of thermal stationary sources and several others in chemical industry, bases on a comprehensive legislation in Germany. The results of this emission reduction strategy are presented by emission inventories for stationary, mainly industrial sources comparing in this paper data for emissions between 1994 and 2001. These results show that the implementation of best available techniques (BAT) at industrial sources for PCDD/F-reduction has been nearly fully exhausted at nearly all relevant sources and extensive overall emission reductions were achieved by the end of the 1990s. Further reductions for PCDD/F are needed for specific sources in metallurgical industries, especially sinter plants, and for domestic furnaces only. For coplanar PCBs (co-PCBs) almost no emission data are available from German sources; a few data from measurements of co-PCB have been published from two waste incineration plants. These measurements show that the emission limit value of 0.1 ng TEQ/m3 is not exceeded by co-PCBs in the waste gas in addition to the background PCDD/F concentration. As a consequence from the new appraisals for toxicity equivalences (TEQ) and tolerable daily intakes (TDI) of the World Health Organisation the Federal Environmental Agency in Germany discusses a level of 1 pg WHO TEQ/(kg(bw) d) as an acceptable limit value for adult's burden, taking into account, that this value is too much for children in the pre- and post-natal age and further action for PCDD/F- and co-PCB reduction is needed for the last sensitive group. As a summary can be reported that PCDD/F and co-PCB intakes into the nutrition chain could not have their origin from stationary industrial sources mainly. More attention should be given to more diffuse source such as residential combustion and others, which are more directly connected to the nutrition chain, like green food drying. Important effects could be expected by restrictions of PCDD/F impacts by regulations for control of feed, feed components and compounds feed for pigs and cattle.     

The optimal use of non-renewable resources: The theory of extraction

The traditional theory of exhaustion is revised to allow for long run capital mobility. This model is extended to include the impact of cumulative environmental damages on the optimal path of resource use. Models and optimal markets are then analyzed for cases where minerals are available over a continuum of quality and where recycling ameliorates inevitable exhaustion of non-renewable resources. Finally, the impact of technological change on long run trends in mineral prices is examined.     

Establishment of a cross-European field site network in the ALARM project for assessing large-scale changes in biodiversity

The field site network (FSN) plays a central role in conducting joint research within all Assessing Large-scale Risks for biodiversity with tested Methods (ALARM) modules and provides a mechanism for integrating research on different topics in ALARM on the same site for measuring multiple impacts on biodiversity. The network covers most European climates and biogeographic regions, from Mediterranean through central European and boreal to subarctic. The project links databases with the European-wide field site network FSN, including geographic information system (GIS)-based information to characterise the test location for ALARM researchers for joint on-site research. Maps are provided in a standardised way and merged with other site-specific information. The application of GIS for these field sites and the information management promotes the use of the FSN for research and to disseminate the results. We conclude that ALARM FSN sites together with other research sites in Europe jointly could be used as a future backbone for research proposals.     

Nitrogen and phosphorus budgets in experimental grasslands of variable diversity

Previous research has shown that plant diversity influences N and P cycles. However, the effect of plant diversity on complete ecosystem N and P budgets has not yet been assessed. For 20 plots of artificially established grassland mixtures differing in plant diversity, we determined N and P inputs by bulk and dry deposition and N and P losses by mowing (and subsequent removal of the biomass) and leaching from April 2003 to March 2004. Total deposition of N and P was 2.3 +/- 0.1 and 0.2 +/- 0.01 g m(-2) yr(-1), respectively. Mowing was the main N and P loss. The net N and P budgets were negative (-6.3 +/- 1.1 g N and -1.9 +/- 0.2 g P m(-2) yr(-1)). For N, this included a conservative estimate of atmospheric N(2) fixation. Nitrogen losses as N(2)O were expected to be small at our study site (<0.05 g m(-2) yr(-1)). Legumes increased the removal of N with the harvest and decreased leaching of NH(4)-N and dissolved organic nitrogen (DON) from the canopy. Reduced roughness of grass-containing mixtures decreased dry deposition of N and P. Total dissolved P and NO(3)-N leaching from the canopy increased in the presence of grasses attributable to the decreased N and P demand of grass-containing mixtures. Species richness did not have an effect on any of the studied fluxes. Our results demonstrate that the N and P fluxes in managed grassland are modified by the presence or absence of particular functional plant groups and are mainly driven by the management.