Beyond climate envelopes: effects of weather on regional population trends in butterflies

Although the effects of climate change on biodiversity are increasingly evident by the shifts in species ranges across taxonomical groups, the underlying mechanisms affecting individual species are still poorly understood. The power of climate envelopes to predict future ranges has been seriously questioned in recent studies. Amongst others, an improved understanding of the effects of current weather on population trends is required. We analysed the relation between butterfly abundance and the weather experienced during the life cycle for successive years using data collected within the framework of the Dutch Butterfly Monitoring Scheme for 40 species over a 15-year period and corresponding climate data. Both average and extreme temperature and precipitation events were identified, and multiple regression was applied to explain annual changes in population indices. Significant weather effects were obtained for 39 species, with the most frequent effects associated with temperature. However, positive density-dependence suggested climatic independent trends in at least 12 species. Validation of the short-term predictions revealed a good potential for climate-based predictions of population trends in 20 species. Nevertheless, data from the warm and dry year of 2003 indicate that negative effects of climatic extremes are generally underestimated for habitat specialists in drought-susceptible habitats, whereas generalists remain unaffected. Further climatic warming is expected to influence the trends of 13 species, leading to an improvement for nine species, but a continued decline in the majority of species. Expectations from climate envelope models overestimate the positive effects of climate change in northwestern Europe. Our results underline the challenge to include population trends in predicting range shifts in response to climate change

Hypertensive encephalopathy in a patient with neonatal thyrotoxicosis

Neonatal hyperthyroidism may give rise to serious cardiovascular complications. A girl with severe thyrotoxicosis in whom hypertensive encephalopathy developed is described. Conclusion Neonatal thyrotoxicosis can give rise to hypertension and may lead to hypertensive encephalopathy

[Towards a national yardstick for the ecological environment.]

Abstract niet beschikbaarIn this report a conceptual method is proposed with which the status of ecosystems in the Netherlands can be described. This method can be used for state of the (ecological) environment reporting. The following issues are discussed: policy needs, current ecological yardsticks, indicator selection, resolution, aggregation of information, presentation of results, ecological models and ecological monitoring programmes. On the basis of this information the conceptual method is proposed at a regional level using target species, ecosystem species and abiotic conditions of target species and target ecosystems. Needs to work out this conceptual method are discussed in terms of research and compared with current reserach programmes of the RIVM and the IKC-NBLF. Ommisions and cornerstones have been identified.DGM/SP RIV