The Importance of I. Horvat’s Unpublished Text on the Historical Development of the Vegetation in South-Eastern Europe

Auf Grund langjähriger Untersuchungen der tertiären und quartären Vegetation Südosteuropas kam der erste Autor (N. Pantić) zu gleichen Ergebnissen, wie der Botaniker I. Horvat durch seine geobotanischen Forschungen bereits vor 30 Jahren. Da jedoch das umfangreiche Kapitel über »Die Pflanzenwelt Südosteuropas als Ausdruck erd- und vegetationsgeschichtlicher Ergebnisse« des Horvatschen originalen Manuskripts im Buch von Horvat, I., Glavač, V. und N. Ellenberg (1973) nicht veröffentlicht wurde, wird in der vorliegenden Arbeit versucht, die Grundgedanken Horvats in kürzerer Form darzustellen und sie mit den Ergebnissen von N. Pantić zu vergleichen. Es handelt sich dabei um Fragen 1. der eigenartigen Entwicklung der Festlandvegetation Südosteuropas während des Tertiärs, die zu einem besonderen Reichtum der Balkanflora führte, wobei Horvat die Bedeutung der »Repere-Floren« schon damals richtig erkannt hat; 2. der Erklärung von Ursachen klimatischer Veränderungen während des Postpliozäns bis heute durch die Anwendung der Theorie von Milankovic (1941), die Horvat sofort angenommen hat; und 3. der Verbindung der tertiär-pleistozänen Vegetation mit der heutigen Vegetation von Südosteuropa.Naša saznanja o razvoju kopnene vegetacije jugoistočne Evrope kroz tercijar i kvartar u ovisnosti o promjenama njezina životnog okoliša, u prvom redu klime i geodinamičkih promjena, sinteza su dugogodišnjih paleobotaničkih istraživanja prvog autora ovog rada (Pantić 1954, 1956, 1967, 1986, 1987). Analogne ideje iznosio je već prije trideset godina profesor botanike dr. Ivo Horvat (1897—1963) na osnovi temeljitih taksonomskih i vegetacijskih istraživanja te paralelnog studija biljnih zajednica i njihovih migracija kroz bližu geološku prošlost, najviše u vezi s promjenama klime (Horvat 1959). U monografiji Horvat,I., V. Glavač H. Ellenberg; Vegetation Südosteuropas, 1974, međutim, izostavljeno je Horvatovo poglavlje: »Biljni svijet jugoistočne Evrope kao izraz geoloških i povijesno-vegetacijskih zbivanja«. U tom neobjavljenom tekstu (120 tipkanih str.) ima više značajnih misli na koje treba upozoriti, jer se one, nedovoljno shvaćene u doba kada je tekst pisan, danas pokazuju ispravnima. Uglavnom se radi o tri značajna problema: 1) Horvat naglašava izuzetnost razvoja kopnene vegetacije jugoistočne Evrope u toku tercijara. U srednjoj i istočnoj Evropi nestale su osjetljive vrste mnogo ranije nego na Balkanu, gdje su se zadržale zaštićene paralelnim gorskim lancima. Pliocenske naslage Balkana su, s obzirom na klimatske odnose, vrlo nalik na srednjoevropski miocen. U jugoistočnoj Evropi uočeno je zaostajanje (duže trajanje) tople klime i vegetacije. Horvat je među prvima primijetio tu činjenicu i naglasio da se treba pri istraživanju razvoja vegetacije osloniti na reperne flore (fixed floras), i ne obazirati se na provodno značenje pojedinih vrsta. Treba također računati s faktorom paleobiogeografskih karakteristika pojedinih pokrajina. 2) U tumačenju promjena u toku ledenog doba Horvat se hrabro odlučio za Milankovićevo tumačenje uzroka klimatskih promjena u antropogenu, iako tada najveći broj paleoklimatologa Milanko-vićevu teoriju nije prihvaćao i ta se koncepcija tek od 1976. smatra definitivno dokazanom, a posebno od simpozija »Milankovitch and Climate, Columbia University, 1982« (Pantić 1983a, 1983 b). Horvat je »naučničkom pronicljivošću« (prema Pantiću) u svojemu rukopisu (str. 41) napisao ovo: »Prihvaćanje pomicanja polova u smislu Wegenera i Koppena može objasniti ledena doba. ali ne međuleđena. Ona su našla genijalno tumačenje prema Milan- koviću (1941) u periodičnim promjenama insolacije u posljednjih 650 000 godina. Milanković je proračunao za sjevernu Zemljinu polutku insolaciju u posljednjih 1 000 000 godina i mogao dokazati, da zbog periodičnih promjena određenih astronomskih veličina i to nagnutosti ekliptike, ekscentričnosti Zemljine putanje i precesije točke proljeća dolazi do periodičnog sniženja i povišenja ljetne temperature«. 3) Uspješno je u Horvatovim shvaćanjima povezan razvoj tercijarne i kvartarne vegetacije sa sadašnjim stanjem vegetacije u jugoistočnoj Evropi. Originalna i iscrpna fitocenološka objašnjenja daje Horvat kao izraz geoloških i povijesno-vegetacijskih zbivanja. Sigurno će proći još mnogo vremena da se odgonetnu svi tokovi promjena vegetacije u toku tercijara i antropogena u jugoistočnoj Evropi, ali i onda će stajati priznanje, da je nepublicirani Horvatov tekst predstavljao značajan doprinos na pravom putu odgonetavanja važne paleoklimatološke, paleobotaničke i geobotaničke problematikeDuring the Tertiary and Quartary the evolution of the continental vegetation of South-Eastern Europe depended on the changes of its environment, especially of the climate and the geodynamical events. This knowledge is the result of a synthesis of long time palaeobotanical investigations of the first author of this paper (Pantic 1954, 1956, 1967. 1986, 1987). Thirty years ago Professor Ivo Horvat (1897—1963) came to similar ideas based on his fundamental research into taxonomy and vegetation as well as on parallel studies of plant associations and their migrations during the near geological past, considering especially the changes of the climate. In the monograph by Horvat, Glavač and Ellenberg : »Vegetation of South-Eastern Europe«, however, the chapter of Horvat’s original manuscript: »The plant world of South-Eastern Europe as an expression of geological and historical vegetational events« was omitted. In this unpublished text (120 typewritten pages) there are many significant ideas, which should be pointed out, because they are — although they were not understood at the time when Horvat has wrote them — now recognized as being correct and valid. There are, in general, three important problems: 1. Horvat points out the exceptionality of the continental vegetation of South-Eastern Europe during the Tertiary. In the Central and Eastern Europe sensitive species disappeared much earlier than in the Balcans, where they survived owing to the protection of the mountain chains. The Pliocene sediments of the Balcans are in respect to climatic conditions much like those of the Miocene of Central Europe. In South- -Eastern Europe a retardation of the warm climate and vegetation occurred. Horvat was one of the first to realize this fact and to point out that one must — when investigating the development of a vegetation — consider the fixed flora (repère flora), regardless of the index significance of several species. It is also necessary to consider the factor of palaeobiogeographical characteristics of a country. 2. Horvat bravely accepted Milanković’s theory of climate changes in the Antropogene, although at that time (untill 1963) most palaeoclimatologists did not agreee with Milanković’s concept until 1976, when his work was definitely accepted, especially since the Symposium »Milankovitch and Climate«. Columbia University, 1982 (Pan tie 1983a, 1983b). His scientific intuition led Horvat to write (p. 41 of his manuscript) : »Acceptance of the movements of the earth’s poles according to Wegener and Koppen can explain the glacial periods, but not the interglacial ones. For them an ingenious interpretation (Milanković 1941) can be found in periodical changes of insolation during the last 650 000 years. Milanković calculated the insolation of the northern hemisphere during the last 1 000 000 years and was able to prove that periodical changes of some astronomical magnitudes, namely the obliquity of the ecliptic, the excentricity of the earth’s orbit and the precession of the vernal equinoxes point cause the periodical decrease or increase in the summer temperature«. 3. In Horvat’s interpretation the development of the Tertiary-Quartary vegetation is successfully connected with the recent situation of the vegetation in South-Eastern Europe. Original and exhaustive phytocoenological explanations have been given by Horvat as an expression of geological and historico-vegetational processes. A long period of research will be needed before all vegetational changes during the Tertiary and Athropogene in South-Eastern Europe can be explained. But even then it will be obvious that Horvat’s unpublished text (Horvat 1963) represents a significant contribution to endeavours way how to approach and solve the significant palaeoclima- tological, palaeobotanical and phytogeographical problems

Paleogeographic evolution of the Southern Pannonian Basin: 40Ar/39Ar age constraints on the Miocene continental series of notthern Croatia

The Pannonian Basin, originating during the Early Miocene, is a large extensional basin incorporated between Alpine, Carpathian and Dinaride fold-thrust belts. Back-arc extensional tectonics triggered deposition of up to 500-m-thick continental fluvio-lacustrine deposits distributed in numerous sub-basins of the Southern Pannonian Basin. Extensive andesitic and dacitic volcanism accompanied the syn-rift deposition and caused a number of pyroclastic intercalations. Here, we analyze two volcanic ash layers located at the base and top of the continental series. The lowermost ash from Mt. Kalnik yielded an 40Ar/39Ar age of 18.07 ± 0.07 Ma. This indicates that the marine-continental transition in the Slovenia-Zagorje Basin, coinciding with the onset of rifting tectonics in the Southern Pannonian Basin, occurs roughly at the Eggenburgian/ Ottnangian boundary of the regional Paratethys time scale. This age proves the synchronicity of initial rifting in the Southern Pannonian Basin with the beginning of sedimentation in the Dinaride Lake System. Beside geodynamic evolution, the two regions also share a biotic evolutionary history: both belong to the same ecoregion, which we designate here as the Illyrian Bioprovince. The youngest volcanic ash level is sampled at the Glina and Karlovac sub-depressions, and both sites yield the same 40Ar/39Ar age of 15.91 ± 0.06 and 16.03 ± 0.06 Ma, respectively. This indicates that lacustrine sedimentation in the Southern Pannonian Basin continued at least until the earliest Badenian. The present results provide not only important bench marks on duration of initial synrift in the Pannonian Basin System, but also deliver substantial backbone data for paleogeographic reconstructions in Central and Southeastern Europe around the Early–Middle Miocene transition

New dasycladalean algae from the Middle Norian (Upper Triassic) of northern Italy (Mt. Pramaggiore, Carnic Prealps)

In the Eastern Southern Alps of northern Italy (Carnic Prealps, Friuli region), the shallow-water carbonate platform deposits of the Dolomia Principale Fm. (Norian– Rhaetian, Upper Triassic) show best-preserved platform to basin facies transition. The palaeontological study of an algal-rich level recovered from the platform margin facies (Mt. Pramaggiore) has displayed a very interesting association of Dasycladales. Two new genera (Bystrickyella and Elliottporella) and four new species (Bystrickyella ottii, Elliottporella morelloae, Palaeodasycladus lorigae and Holosporella conradii) have been described. These new data suggest that the Norian represents a period of turnover in the evolutionary history of the green algae community. This stage, placed between two extinctions, end-Ladinian and end-Norian, is here interpreted as a re-organization period of the evolutionary schemes of Dasycladales. The new lineages originated in the Norian developed further and characterized the Early Jurassic scenery