Abstract:The Holocene delivers a unique possibility to establish climatic stratigraphic boundaries based on detailed chronostratigraphy reflected in various facies of continental sediments, in their lithological parameters and organic remains. These sediments are dated by the 14 C method in the case of organic remains, by counting annual laminations in lacustrine facies, and by dendrochronological method in the case of fluvial sediments. The existence of well dated profiles enables to reconstruct various climatic parameters like amplitudes of seasonal temperatures, types and frequency of extreme rainfalls and floods and, finally, to distinguish rare rapid changes and most frequent gradual ones. This reconstruction is based on the analogous effects of various types of present-day rainfalls. The current authors present a critical review of existing chronostratigraphic divisions starting from simple millennial division by Mangerud based on Scandinavian palynological stratigraphy of peatbogs and Starkel's concept based on fluctuations in rainfall and runoff regime reflected in fluvial and other facies of continental deposits. In the last decades, the calibration of 14 C dates allowed a new approach to be used for the construction of the probability distribution function of these dates in various facies or types of sediments, which formed a background for distinguishing and correlating climatic phases and defining boundaries between them. These approaches have been creating new opportunities for revision of the existing chronostratigraphy. The aim of this paper is to present a revised version of chronostratigraphic division based on climatic fluctuations reflected in various facies of sediments on the territory of Poland and discuss their correlation with other European regions and global climatic changes.

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ABSTRACT.The "calibration" of arbitrarily defined (in some sense, "conventional") ages, given in conventional radiocarbon years BP, is now becoming necessary because the term "radiocarbon age" is used less often in archaeological and Quaternary practice. The standard calibration procedure is inappropriate here because Mangerud's boundaries are not measurement results. Thus, another approach to the problem is proposed in order to model the natural situation of many, uniformly distributed, dated samples, which should be similarly divided by the original and "calibrated" boundary. However, the result depends on the value of the typical measurement error and is not unequivocal.

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Taxus baccata L. has a scattered distribution and the decline of yew woodlands is observed across the entire species range. Passively protected populations in the central and northern part of their distribution are declining without human intervention. However, the establishment of new yew populations is observed in habitats that have been significantly transformed by humans. The following question need to be answered: why do yews find better in environmental conditions that have been strongly modified by humans compared to natural systems? The Quaternary history might be the key to understand the current yew situation. As suggested by palaeobotanical studies, pollen of T. baccata was observed at optima of the interglacials, but in subsequent periods, it has been displaced by that of other shade-tolerant species. Pollen diagrams indicate that after the last glaciation, the yew did not appear earlier than other shade-tolerant species and did not have the opportunity to become common in occurrence, as in previous interglacial periods. As a result, yews occur only as relict populations within environmental islands where the competition with other shade-tolerant species is low. The negative human impact on yew is well-documented, but limitations resulting from the biology of this species are also very important. T. baccata is a species whose current scattered distribution may explain the Quaternary history. Yew situation is better in artificial conditions because people reduce competition from other trees species and deer pressure. Possible positive impact of human on yew distribution in the past is also discussed. The current biological condition of this species suggests the need for active protection.