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101.
ABSTRACT

The leadership dynamics between the European Council, the Council and the Member States in European Union (EU) environmental policy since the 1970s are analysed. The puzzle is that, although the EU was set up as a ‘leaderless Europe’, it is widely seen as an environmental leader, albeit sometimes as a one-eyed leader amongst the blind. While differentiating between leadership types, it is argued that the European Council has the largest structural, the Council the most significant entrepreneurial, and the Member States the most important cognitive and exemplary leadership capacities. Most day-to-day environmental policy measures are negotiated by the Environment Council (in collaboration with the European Parliament). The European Council’s increased interest in high politics climate change issues is largely due to the EU’s global leadership ambitions. Member States have traditionally formed environmental leadership alliances on an ad hoc basis although this may be changing.  相似文献   
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103.
Plants evolve the production of wound-activated compounds (WACs) to reduce grazing pressure. In addition, several plant-produced WACs are recognized by various invertebrates, playing the role of infochemicals. Due to co-evolutionary processes, some invertebrates recognize plant infochemicals and use them to identify possible prey, detect the presence of predators or identify algae containing various classes of toxic metabolites. Different metabolites present in the same algae can play the role of toxins, infochemicals or both simultaneously. We investigated the infochemical activity of compounds extracted from three diatoms epiphytes of the seagrass Posidonia oceanica, by conducting choice experiments on invertebrates living in the same community or in close proximity. Furthermore, the specific toxicity of the extracts obtained from the same algae was tested on sea urchin embryos using a standard bioassay procedure, to detect the presence of toxins. The comparison of the two effects demonstrated that invertebrates are subjected to diatom wound-activated toxicants when these algae are not associated with their own habitat, but they are able to recognize volatile infochemicals derived from diatoms associated with their habitats. The specific toxicity of WACs was shown to be inversely correlated to the perceptive ability of invertebrates towards volatile compounds liberated by the same algae. Hence, when the recognition of specific algae by a given invertebrate species evolves, their detrimental effects on the receiving organism may be lost.  相似文献   
104.
The performance of narrow buffer strips in abating the NO3-N concentrations in the water coming from cropland was tested in an experiment carried out on the low plains of the Veneto Region (northeast Italy). The buffer was composed of a 5-m wide grass strip and a 1-m wide row of trees. Maize and wheat were cultivated in the neighbouring field during the monitoring period (December 1997-June 1999). Four experimental conditions were monitored, deriving from a combination of two levels of crop N fertilisation and two sizes of buffer trees. The narrow buffer was very effective in abating NO3-N concentrations, allowing water to be discharged with a concentration always below 2 ppm. Its zone of influence might be bigger than its simple width. The abatement was also efficient during winter. Tree size showed no evident effect on the reduction of the concentration.  相似文献   
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