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60 páginas, 7 figuras, 1 tabla. ; Large uncertainties exist in our knowledge of regional emissions of non-methane biogenic volatile organic compounds (BVOC). We address these uncertainties through a two-pronged approach by compiling a state of the art database of the emissions potentials for 80 European forest species, and by a model assessment and inter-comparison, both at the local and regional scale, under present and projected future climatic conditions. We coupled three contrasting isoprenoid models with the ecophysiological forest model GOTILWA+ to explore the interactive effects of climate, vegetation distribution, and productivity, on leaf and ecosystem isoprenoid emissions, and to consider model behaviour in present climate and under projected future climate change conditions. Hourly, daily and annual isoprene emissions as simulated by the models were evaluated against flux measurements. The validation highlighted a general model capacity to capture gross fluxes but inefficiencies in capturing short term variability. A regional inventory of isoprenoid emissions for European forests was created using each of the three modelling approaches. The models agreed on an average European emissions budget of 1.03 TgC a −1 for isoprene and 0.97 TgC a −1 for monoterpenes for the period 1960–1990, which was dominated by a few species with largest aerial coverage. Species contribution to total emissions depended both on species emission potential and geographical distribution. For projected future climate conditions, however, emissions budgets proved highly model dependent, illustrating the current uncertainty associated with isoprenoid emissions responses to potential future conditions. These results suggest that current model estimates of isoprenoid emissions concur well, but future estimates are highly uncertain. We conclude that development of reliable models is highly urgent, but for the time being, future BVOC emission scenario estimates should consider results from an ensemble of available emission models. ; This study was funded through the GREENCYCLES Marie-Curie Biogeochemistry and Climate Change Research and Training Network (MRTN-CT-2004-512464) supported by the European Commission's Sixth Framework program. Data was supplied by the ALARM (Assessing LArge-scale environmental Risks for biodiversity with tested Methods: GOCE-CT-2003-506675) and ATEAM (Advanced Terrestrial Ecosystem Analysis and Modelling: EVK2-2000-00075) project, from the EU Fifth Framework for Energy, Environment and Sustainable Development and the CSIC-Estonian Academy of Sciences collaborative project. TK acknowledges further support from the CCTAME (Climate Change – Terrestrial Adapta- tion and Mitigation in Europe, FP7 212535) project. JP acknowledges additional funding from the Spanish Ministry of Education and Science project (CGL2006-04025), Consolider Montes (CSD2008-00040), and a Catalan Government project grant (SGR2008-00312) and UN from ¨ the Estonian Science Foundation (Grant 7645) and the Estonian Ministry of Education and Science (grant SF1090065s07). ; Peer reviewed

12 páginas, 7 figuras, 1 tabla. ; In the north rim of the Mediterranean region, where forest cover is increasing as a result of landabandonment and temperatures are rising as a result of climatechange, there is increasing interest for the effects of such changes on the runoff of water courses. This is a paramount issue for the conservation of many freshwater habitats and species. In this work we studied the effects of both an increase in forest cover after depopulation and landabandonment and an increase in temperature on the runoff of aMediterraneancatchment and on the aquatic and semi-aquatic fauna species of the stream (Olzinelles valley, NESpain). Although in our simulation no decreasing trend in runoff is detected, the monthly runoff-rainfall ratio is now 15% lower than 30 years ago, a fact that may be attributed to a drier period rather than to the small afforestation experienced by the catchment in the last decades. Other factors such as increasing temperatures, changing rainfall patterns and increasing canopy cover are discussed. The observed decrease in the water flow has caused the disappearance of white-clawed crayfish (Austropotamobius pallipes), Mediterranean barbel (Barbus meridionalis), chub (Squalius cephalus), European eel (Anguilla anguilla), and southern water vole (Arvicola sapidus). Our results suggest that in a progressively warmer climate, and especially after landabandonment processes, management of Mediterranean mountain areas should be oriented towards an appropriate distribution of agrarian and forest land-covers in terms of wateravailability. Down to the stream scale, the pools that keep water throughout the year should be conserved and extended to enhance its potential to maintain aquatic and semi-aquatic species populations. ; I.O. received a grant of the Ministry of Innovation, Universities and Enterprise of the Catalan Government while conducting this research (Ref. 2005FI00505). We also thank financial help from the Spanish Government (grants CGL2006-04025/BOS and Consolider-Ingenio Montes CSD2008-00040) and the Catalan Government (SGR2009-458). ; Peer reviewed