Quaternary palaeoecology has traditionally been associated with the reconstruction of past biota and past environments over long time periods such as the Holocene period. Recent methodological developments and conceptual advances have resulted in an 'applied palaeoecology' that can address specific ecological and environmental questions over the last 100-200 yr, the time span of primary interest to nature conservarionists. The contributions of palaeoecology to the assess ment of naturalness of ecosystems, to the assessment of the fragility of ecosystems, to the assessment of the conservation status of rare species, and to the development of a factual basis for attempts at ecosystem enhancement and restoration are discussed, with reference to palaeoecological studies in Scotland, England, southwest Ireland, and Sweden. Palaeo ecological results indicate that few, if any, vegetation types in western Europe are natural. Palaeoecology can provide unique insights into the fragility of ecosystems in response to human activity and other biotic factors such as grazing and to acidification. Palaeoecology can contribute basic information required for understanding the causes of recent decline of taxa such as the natterjack toad, aquatic macrophytes. and arctic-alpine plants. Palaeoecology is often the only source of baseline data about past ecosystem composition and function that are essential for any realistic attempts at ecosystem restoration or enhancement.