During the last decades, climate and land use changes led to an increased prevalence of megafires in Mediterranean-type climate regions (MCRs). Here, we argue that current wildfire management policies in MCRs are destined to fail. Focused on fire suppression, these policies largely ignore ongoing climate warming and landscape-scale buildup of fuels. The result is a 'firefighting trap' that contributes to ongoing fuel accumulation precluding suppression under extreme fire weather, and resulting in more severe and larger fires. We believe that a 'business as usual' approach to wildfire in MCRs will not solve the fire problem, and recommend that policy and expenditures be rebalanced between suppression and mitigation of the negative impacts of fire. This requires a paradigm shift: policy effectiveness should not be primarily measured as a function of area burned (as it usually is), but rather as a function of avoided socio-ecological damage and loss.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. In the Soay sheep population of Hirta (St. Kilda), high winter mortality occurs every 3-4 years following summers when population density exceeds 2-2 sheep ha-'. During these die-offs, more than 50% of adults, 70% of yearlings and 90% of lambs die and population density falls by around 65%. 2. This paper investigates the extent to which density-related changes in early growth might be responsible for fluctuations in over-winter survival and population size. Individual differences in birth weight and subsequent growth rates exert a strong influence on the survival of lambs through the neonatal period and through the first winter of life when the effects of population density on survival have been taken into account. 3. High population density in summer is associated with reductions in the weight of lambs entering the winter and low birth weights the following spring. Densityrelated changes in birth weight are closely correlated with changes in neonatal mortality. However, annual variation in neonatal mortality contributes little to fluctuations in population size. 4. Despite the relationship between individual variation in birth weight and survival through the first winter, density-related changes in the weight of lambs at birth and at 4 months contributed little to density-related changes in survival through the first winter. This was primarily because birth weight and early growth were most heavily depressed in springs that followed die-offs and were followed by winters when mortality (and density) were low. These results indicate that density-related changes in lamb growth are unlikely to be an important cause of die-offs in this population.

Roughly 3% of the Earth's land surface burns annually, representing a critical exchange of energy and matter between the land and atmosphere via combustion. Fires range from slow smouldering peat fires, to low-intensity surface fires, to intense crown fires, depending on vegetation structure, fuel moisture, prevailing climate, and weather conditions. While the links between biogeochemistry, climate and fire are widely studied within Earth system science, these relationships are also mediated by fuels-namely plants and their litter-that are the product of evolutionary and ecological processes. Fire is a powerful selective force and, over their evolutionary history, plants have evolved traits that both tolerate and promote fire numerous times and across diverse clades. Here we outline a conceptual framework of how plant traits determine the flammability of ecosystems and interact with climate and weather to influence fire regimes. We explore how these evolutionary and ecological processes scale to impact biogeochemical and Earth system processes. Finally, we outline several research challenges that, when resolved, will improve our understanding of the role of plant evolution in mediating the fire feedbacks driving Earth system processes. Understanding current patterns of fire and vegetation, as well as patterns of fire over geological time, requires research that incorporates evolutionary biology, ecology, biogeography, and the biogeosciences.

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