The Balkans as Prime Glacial Refugial Territory of European Temperate Trees

Abstract

Every subdiscipline investigating the fossil record has its own holy grail, be they soft body tissues, or ancient DNA, or missing links in human ancestry, the level of its desirability determined not only by the importance in understanding particular aspects of the history of life, but also by the degree of its elusiveness. In the case of European Quaternary palaeobotany the search for cold stage refugia of temperate trees would probably qualify under this category. Ever since the first full-glacial pollen diagrams from southern Europe (e.g Wijmstra, 1969; Florschütz et al 1971) showed steppe-dominated landscapes, implying that forest biomes had not simply shifted en mass southwards as ice sheets expanded, the whereabouts of temperate elements of the flora has been a topic of continuous discussion. The prevailing hypothesis has been that remnant tree populations found refuge in the southern peninsulas of Europe where they survived in suitable microhabitats in mid-altitude zones and in locally moist sites in lowland and coastal areas (e.g Beug, 1968, 1975; Frenzel, 1968, 1979; Lang, 1970; van der Hammen et al 1971; Bennett et al 1991). The presumed small size of such populations and the relative lack of full-glacial evidence means that direct palaeobotanical detection has been difficult, and it is precisely this aspect of the problem that provides the element of fascination in the search for glacial refugia. Indeed, when reviewing the large number of publications on this issue, one is often struck by a tendency (if not a desire) to infer the presence of refugial populations on the basis of sometimes indirect and even tenuous evidence.