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There is much interest in predicting the impact of global warming on the genetic diversity of natural populations and the influence of climate on biodiversity is an important ecological question. Since Holocene, we face many climate perturbations and the geographical ranges of plant taxa have changed substantially. Actual genetic diversity of plant is a result of these processes and a first step to study the impact of future climate change is to understand the important features of reconstructed climate variables such as temperature or precipitation for the last 15,000 years on actual genetic diversity of forest. We model the relationship between genetic diversity in the European beech (Fagus sylvatica) forests and curves of temperature and precipitation reconstructed from pollen databases. Our model links the genetic measure to the climate curves. We adapt classical functional linear model to take into account interactions between climate variables as a bilinear form. Since the data are georeferenced, our extensions also account for the spatial dependence among the observations. The practical issues of these methodological extensions are discussed. [ABSTRACT FROM AUTHOR]

After the last glacial maximum (LGM; 18,000 years. bp) plants migrated onto areas made free by the retreating ice sheets. Pollen records document changes in ecosystems and are an important proxy for the reconstruction of climate parameters. Here, we quantify changes in January temperature (Tjan) over the past 14,000 years using 216 European pollen records. We used functional principal component analysis to evaluate the patterns of change over this period of time. Between 14 and 12 ka, Tjan records show comparable changes across Europe. After this time period, northwest and southeast Europe experienced differing trends in Tjan, trends that became pronounced by 9 ka. The spatial gradient of Tjan records is well-correlated with the overall change from steppe to increasingly diverse forest ecosystems. In particular, differential incorporation of conifer vs. deciduous species into forest ecosystems, based on differential colonization out of refugia, likely resulted in albedo gradients over Europe that affected regional Tjan. [ABSTRACT FROM AUTHOR]

The Velay sequence (France) provides a unique, continuous, palynological record spanning the last four climatic cycles. A pollen-based reconstruction of temperature and precipitation displays marked climatic cycles. An analysis of the climate and vegetation changes during the interglacial periods reveals comparable features and identical major vegetation successions. Although Marine Isotope Stage (MIS) 11.3 and the Holocene had similar earth precessional variations, their correspondence in terms of vegetation dynamics is low. MIS 9.5, 7.5, and especially 5.5 display closer correlation to the Holocene than MIS 11.3. Ecological factors, such as the distribution and composition of glacial refugia or postglacial migration patterns, may explain these discrepancies. Comparison of ecosystem dynamics during the past five interglacials suggests that vegetation development in the current interglacial has no analogue from the past 500,000 years. [ABSTRACT FROM AUTHOR]