Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 90. (Budapest 1998)

Medzihradszky, Zs. ; Bajzáth, J.: The occurrence of arctic-alpine Betula species in the Hungarian Pleistocene

Statistical method. To confirm this result, we measured the grain diameter and the pore depth of the studied pollen grains. Based on the measurements of recent Betula species, BIRKS (1968) showed that the grain diameter/pollen depth ratio (Lt/P-alt) is a suitable parameter to distinguish Betula pubescens from Betula nana. The mean ratio for Betula nana is between 11.32-11.47, whereas this ratio for Betula pubescens is 7.76-7.93. The results of our measurment and calculations, the grain diameter/pollen depth ratio are shown on Fig. 10. The Lt/P-alt value of each pollen grain was plotted independently from the previously morphological identification. We can distinguish one group between 6 and 8 and an other one between 10 and 12 values of the y axis. In our opinion, the first group corresponds the Betula alba type, while the second one represents the Betula nana type. The Betula pollen with values between 8-10 are thought to represent an indeterminated Betula type. Based on the morphological and statistical analysis, 30% of the Betula pollen in our pollen spectra is Betula nana, 57% is Betula alba, while 13% is unidentified Betula type. CONCLUSIONS We identified the Betula nana type by means of single pollen morphology and confirmed our results through a statistical treatment using the Birks' method (BIRKS 1968). We proved the occurrence of arctic Betula species in the Pleistocene of Hungary by palaeobotanical methods. The results of the macrofossil and pollen analysis are of special importance because they represent the first record of these typical glacial species from the vegetational history of Hungary. Further investigation of the locality is necessary. * * * Acknowledgements - We wish to thank archaeologist A. FIGLER who made available this material for the investigations; Z. TÓTH for the macrofossil photos and W. GRANOSZEWSKI (W. Szafer Institute of Botany, Cracow) for his help in the pollen morphological identification. This study was supported by the project No. 21 of the Hungarian Academy of Sciences and the Polish Academy of Sciences. REFERENCES BIALOBRZESKA, M. & TRUCHANOWICZÓWNA, J. (I960): Zmiennosc ksztaltu owoców i lusek europejskich brzóz (Betula L.) oraz oznaczanie ich w stanie kopalnym. (The variability of shape of fruits and scales of the European birches (Betula L.) and their determination in fossil materials.) - Mon. Bot. 9 (2): 1-93. BIRKS, H. J. B. (1968): The identification of Betula nana pollen. - New Phytol. 67: 309-314. ERDTMAN, G., BERGLUND, B. & PRAGLOWSKI, J. (1961): An introduction to a Scandinavian pollen flora. - Almquist & Wiksell, Stockholm, 92 pp. GAILLARD, M.-J. (1983): On the occurrence of Betula nana L. pollen grains in the Late-Glacial deposits of Lobsingsee (Swiss Plateau). Studies in the Late Quaternary of Lobsingsee 2. - Revue de Paléobiologie 2: 181-188. GODWIN, H. (1956): The History of the British Flora. - Cambridge University Press, Cambridge, 384 pp.