Pollen analysis studies the content of pollen grains in various stratified natural archives – lake sediments and peat accumulations. Generally, organic, permanently waterlogged sediments with acidic or neutral pH reaction are required for this purpose. Pollen-analytical method is used for obtaining proxy-data about the occurrence of plants in the vicinity of investigation sites. Pollen determinations are based on morphological criteria and it is not always possible to reach the species level. Fortunately, this is no essential obstacle for our research. Pollen data are stored in an integrated data basis, which is in the case of the Czech Republic derived from national data basis PALYCZ. The age of individual pollen samples is obtained directly using radiocarbon dating, or indirectly through interpolation from neighbouring radiocarbon dates and/or through correlation with other, geographically close by pollen records.