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Aim: Among the various possible approaches to assess whether a species is native or introduced, the analysis of subfossil pollen and spores from natural archives is a valuable tool. Requirements include a sufficiently high taxonomic resolution of the pollen morphology, as well as sufficient temporal and spatial resolution. The aim of this study is to show the usefulness of this method in solving whether the taxon is native or introduced.
Location: The results are derived from two islands of the Azores: Flores and Pico. Methods: Analysis of pollen and spores in lake sediments; radiocarbon dating of the studied sediments.
Results: Selaginella kraussiana (Kunze) A. Braun has occurred on the Azores Islands at least for the last 6000 years.
Main conclusions: Different authors had assigned three different types of status to Selaginella kraussiana: native, introduced (invasive), or uncertain. High numbers of spores of this taxon were present in the sediment cores from the two studied lakes already several thousand years before the Portuguese discovery and the Flemish settlement in the 15th century. This proves that the species is native on the Azores Islands. Pollen and spore analysis can therefore contribute to historical biogeography not only regarding questions about pre-Quaternary plate tectonics but also about early human impact.
van Leeuwen, J.F.N., Schäfer, H., van der Knapp, W.O., Rittenour, T.M., Björck, S., Ammann, B., 2005, Native or introduced? Fossil pollen and spores may say. An example from the Azores Islands: NEOBIOTA, v. 6, p. 27-34