Dr. Fűköh Levente szerk.: Malakológiai Tájékoztató 16. (Eger, 1997.)
FŰKÖH, L.: Holocene climate changes as model of global climate change
The fauna of the southern part of the cliff is very similar to the Early-Holocene malacological material (Boreal phase). While the fauna of the northern parts of the cliff can be correlated with the malacological material of the Late-Holocene sediments (Atlantic phase). (Fűköh, L. 1980). The mean temperature and relative humidity at the sampling locality of the south mall of the cliffs were 22,7°C and 61,8%, while the same valves in the case of the northern wall of the cliffs are 20,1 C° and 72,7%. The differences are 2,6C° and 10,9%. Applying the principle of actualism we can state that the difference of the temperature between the two climate phase of the Holocene must have been 2C° taking consideration the mean temperature of July. While the difference of the relative humidity must have been 10%. The latter is more determinant from the point of view of the composition of the Mollusc fauna. These data are agree with those differences which were measured with "vole thermometer method". According to this the mean temperature of July could have been 21,8C° during the Atlantic phase, while 22,2C° in the Boreal phase (Kordos, L. 1978, Kretzoi, M. 1959). The actualpaleontological examination is completed by data of biometrical analysis. Both of the recent fauna and the Holocene one contain Granaria frumenium abundantly. There is a shell-morphological method worked out by Domokos, T. (Domokos, T. 1982). With the help of this method we have done the biometrical examinations of recent and fossil specimens (Domokos, T - Füköh, L. 1984). According to this the following conclusions have been drawn: the influence of temperature and humidity on the changing of shell morphological data agree with the results of the examinations analysing the connection of microclimate and faunal composition. III. The second significant climate change - on the basis of the change of fauna composition - took place at the boundary of Atlantic and Subboreal phases. At the territory of medium high mountain ranges increase of relative frequency of species preferring open spaces: Vallonia cos tata, Granaria frumentum, Aegopinella minor, Chondrula tridens (Granaria frumentum biozone). It refers to retraction of woods and spreading of scrubby territories. In lacustrine sediments appearance of characteristic bag species can be observed. Instead of Bithynia tentaculata, the Bithynia leachi gets more frequent. Beside species preferring permanent water cover appear those species which lead alternative way of life. And there is an immigrant species from north-west in the fauna, the Gyraulus riparius. The above mentioned changes refer to climatic deterioration. It is presumably the sign of a cooler and dryer climate (Gyraulus riparius - Bithynia leachi biozone). According to the paleobotanists the climate at the beginning of this climate phase there was humid and cool, later it became dryer. The Subboreal phase is the beginning of corn-production in the Carpathian basin. The result of this anthropogenous influence was the decrease of natural vegetation. IV. Climate change is signed by the malacological material at the boundary of Subboreal and Subatlantic phases again. Species preferring open spaces are forced back. Closed forest are dominant at the territory of medium high mountain ranges. The climate was warm and humid according to the malacofaunae: Laciniaria biplicata, Laciniaria plicata, Clausiliapumila, Ruthenica filograna, Aciculapolita, Helicigona faustina, Monacha cartusiana (Acicula polita-Helicigona faustina biozone). Faunae of lacustrine sediments are not suitable for determination of environmental changes that time though significant decrease can be observed in the frequency of Bithynia leachi and Gyraulus riparius
