Phenological analysis of the Last Glacial vertebrates from the territory of Moravia (the Czech Republic) – Continuity and change in faunistic communities
|Klíčová slova||Moravia, Last Glacial, vertebrates, changes in assemblage diversity, migration, palaeoecology, environment|
|Citace||MUSIL, Rudolf. Phenological analysis of the Last Glacial vertebrates from the territory of Moravia (the Czech Republic) – Continuity and change in faunistic communities. Fossil Imprint / Acta Musei Nationalis Pragae, Series B – Historia Naturalis. Prague: National Museum, 2018, 74(3-4), 199-236. DOI: https://doi.org/10.2478/if-2018-0015. ISSN 2533-4050 (tisk), 2533-4069 (online). Also available from: https://publikace.nm.cz/periodicals/fiamnpsbhn/74-3-4/phenological-analysis-of-the-last-glacial-vertebrates-from-the-territory-of-moravia-the-czech-republic-continuity-and-change-in-faunistic-communities|
Due to the vertical zonality of the studied area, its environment varied greatly over a relatively short distance within the same time span. It is possible to distinguish the following different types of environment:
(1) Alluvial ﬂoodplains around larger water ﬂows. I assume in the Last Glacial there was continuous coniferous forest, with occasional sporadic occurrences of thermophilous deciduous trees in favourable locations mainly in south Moravia.
(2) Lower foothills up to about 300 m a.s.l. along the ﬂoodplains, probably the most widespread type of environment in the studied area. Open grasslands with isolated trees and shrubs were predominant.
(3) At the higher altitudes of the hills (ca. 300–500 m a.s.l.) there was only steppe.
(4) The highest parts of highlands and the mountains (500–1,400 m a.s.l.). During the cold and dry events these areas were mostly without grassy vegetation.
The boundaries of the above mentioned environments ﬂuctuated throughout the whole of the Last Glacial.
A series of new investigations of Last Glacial Moravian sites took place over the recent decades. The result was a relatively large amount of fossil vertebrate ﬁndings, from karst areas (caves), and from open air sites. All ﬁndings were assigned to precisely deﬁned layers which were in most cases radiometrically and/or archaeologically dated. It allowed association of the fauna communities with stratigraphical events and therefore produced a clearer picture of changes during the entire Last Glacial.
The study showed that the species structure of the communities was not stable during the Last Glacial. The changes did not exhibit gradual linear development. The time span of the individual communities varied greatly. In two cases a total species change occurred very rapidly. In other cases the changes occurred over a longer period of time and may have involved penetration of new species into existing communities to a signiﬁcant extent.
The changes of communities associated with single stratigraphical events were palaeoecologically evaluated. In comparison with changes in the environment, I can conclude that both changes occurred simultaneously. I am therefore convinced that the primary impulse for community change was induced by environmental change.
The Eemian communities of regions east of Germany differ from coeval communities of Western and the west part of Central Europe. This difference was driven by variation in precipitation, a more humid climate in the West and continental climate in the East. We have therefore two different Eemian provinces in Central Europe, the more humid west (oceanic weather) and the drier east (continental weather).
The ﬁrst half of the Last Glacial, about 40 ka from its beginning, had a wide range of climatic oscillations of different intensity. In layers of Moravian localities with interglacial species, the numbers of ﬁnds are always limited (small number). They were previously assigned to the Eemian. The earlier stratigraphic scale of the Late Pleistocene corresponded with this view. According to recent opinion, however, the rare ﬁnds of interglacial species in these localities are not from the Eemian interglacial, but from the ﬁrst interstadials of the Last Glacial.
Larger temperature oscillations occurred only in the second half of the Last Glacial and the most signiﬁcant cooling was at the very end of this time.
In the ﬁrst occurrence of the typical Holocene assemblage in the Moravian Karst there are still some species which are typical for the Last Glacial (reindeer and lemmings). Lemmings died out ﬁrst, but reindeer survived up to the Neolithic age.
This area had, and still has today, differing environments within a relatively short distance caused by vertical zonation. There was a signiﬁcantly colder climate in the deep and relatively narrow valleys. The upper part of the insolation slopes was mainly covered with grass and the average annual temperature there was much higher than in the valleys. This was reﬂected of course in the fauna.
The in-migration of animals was not only via a meridional route. Migration was not only caused by oscillation of the average temperature or rainfall, but also by the need to ﬁnd the best conditions for living. Seasonal migration was caused mainly by annual changes in the energy value of the food plants.