Nikolaos Athanasiadis

Late-glacial and Holocene vegetation and climate change at the Palü glacier, Bernina Pass, Grisons Canton, Switzerland

Pollen and macrofossil data from Alpe PAlü, south-eastern Switzerland, are presented. On the basis of these data and the geomorphological evidence for local glacier movement, Holocene climatic oscillations and vegetation change at this upland site (1940 m asl), are reconstructed. The morainic deposits and glacial clays, as well as the pollen data from the base of the pollen profile, clearly show that the Palü glacier, after its retreat from the Cavaglia (Egesen) stade, readvanced once again shortly before the mid-Preboreal. This re-advance was considerably greater than that dating to the Little Ice Age. This early Holocene climatic event is referred to as the Palü Oscillation (Palü-Schwankung) and is considered to be broadly contemporaneous with the previously described Schlaten Oscillation (Schlate n-Schwankung) in the Austrian Alps. The reforestation of the forefield of the moraine was interrupted at least twice during this oscillation, and, compared with neighbouring sites at the same altitude, it appears to be at least 500–700 years younger, i. e. it post-dates 9400 B.P. Though the Palü Oscillation is a Holocene phenomenon, the associated vegetation changes are Late-glacial in character, e.g.Arlemisia and Chenopodiaceae increase andHippophaë is recorded.Alnus viridis replacesBelula andSalix, which were important in the earlier part of the Holocene, at about 5000 B.P. There is no clear evidence that forest burning is attributable to human activity. The use ofLarix-dominated areas as pasture (Lärchwiesen) begins in the mid-Bronze Age. A strong decline inPicea (spruce) andLarix (larch), and an increase in Poaceae,Plantago and other herbs in the uppermost horizons reflect more intensive pastoral farming that began in the high Middle Ages.

Contribution to the knowledge of the vascular flora of NE Greece: Floristic composition of the beech (Fagus sylvatica L.) forests in the Greek Rodopi

Abstract Tsiripidis, I. & Athanasiadis, N.: Contribution to the knowledge of the vascular flora of NE Greece: Floristic composition of the beech (Fagus sylvatica L.) forests in the Greek Rodopi. — Willdenowia 33: 273–297. — ISSN 0511-9618;

Woodland history of northern Greece from the mid Holocene to recent time based on evidence from peat pollen profiles

The woodland history of the northern mountainous parts of Greece is considered in the context of pollen profiles from bogs in Rhodopes, Lailias-Vrontou, Paiko, Voras and Pieria. In the time period covered by these diagrams (only those from Voras and Lailias extend back to the 7th millennium B.P.) the overall trends in the woodland history at the particular sites are comparable but there are also substantial differences that are attributed to the effects of human influence which varied in time, intensify and extent. The earlier phase, which corresponds to the Atlantic period of Firbas, is characterized by mixed deciduous woodlands with Quercus or Tilia the main components. This is followed by the phase (Subboreal) in which coniferous woodlands, which consisted of Abies and Pinus, dominated. In this time, Fagus gradually expanded. In the final phase (Subatlantic), Abies becomes more or less extinct and Fagus has a dominant role. These developments broadly correspond with those recorded in pollen profiles from Central Europe.

Classification and gradient analysis of the beech forest vegetation of the southern Rodopi (northeast Greece)

Pure and mixed beech forest vegetation of the southern Rodopi range (northeast Greece) was studied using 614 relevés and multivariate analyses (TWINSPAN and DCA). Classification of the relevés resulted in 12 vegetation units, 8 of which were ranked as associations or communities and the rest as subcommunities and variants. DCA diagrams of relevés and taxa indicated that floristic differentiation was attributed mainly to factors such as altitude (affecting temperature and humidity), soil nutrient content and substrate type (affecting physical and chemical soil properties).Differential taxa of vegetation units were chosen based on their phi coefficient values, which were calculated from three different percentage synoptic tables that corresponded to three ranks (ecological groups, associations and communities, and subcommunities and variants) of floristic differentiation. The calculation of phi coefficient on the basis of relative constancy of taxa helps to overcome the problem of the dependence of fidelity values on the number of relevés per vegetation unit and to facilitate the better investigation of the floristic differentiation even of rare vegetation units represented by a small number of relevés. Furthermore, the calculation of fidelity values for different hierarchical levels enables a more detailed and thorough investigation of the floristic differentiation of the vegetation units.

Pollen morphology in relation to the taxonomy and phylogeny of some native Greek Aegilops species

The pollen morphology of some native Greek Aegilops species is investigated in LM (quantitative pollen characters) and SEM (exine sculpture) using acetolysed material. Furthermore, quantitative data are subjected to a multivariate analysis. The tetraploid Ae. cylindrica and its diploid parent Ae. caudata show a distinct morphological affinity as regards their quantitative pollen profile and the features of the exine sculpture. The tetraploid Ae. triuncialis is morphologically divergent from both its parents Ae. caudata and Ae. umbellulata due to the very large values of its quantitative pollen characters. However, the SEM survey of the exine sculpture indicates a rather high degree of similarity between Ae. triuncialis and Ae. umbellulata. No significant differences have been found between the two varieties of Ae. caudata (caudata and polyathera) concerning the quantitative pollen characters as a total or the morphology of the exine sculpture. The resultant clustering of the taxa on the basis of the quantitative pollen characters as well as the recorded similarities of their exine pattern are related to their sectional classification based on cytogenetical and morphological data.

4. Mount Paiko (northern Greece)

The peat bog lies in the middle of the northern part of Mount Paiko (41 ̊ 399 230 N, 22 ̊ 189 170 E; 1080 m a.s.l.; size ca. 0.25 ha) about 3.5 km south to southwest of Archangelos village. Deciduous oak forests interspersed with stands of chestnut and lime as well as beech forests at higher altitudes constitute the vegetation of Mount Paiko (Korakis, 2003). Beech also forms the forest limits. The peat bog is located in the transition zone between oak and beech forest. The climate is characterized as humid continental, with short warm summers (Dfb type according to Köppen). The mean annual temperature and precipitation are 12 ̊C and 558.3 mm, respectively.

Pollen Morphology and its Contribution to the Taxonomy of Some Native Greek aegilops Species.

Pollen morphological characters (mainly those of the exine sculpture) have been used as a means in studying the phylogeny and taxonomy of certain genera of the Gramineae family(Grant 1972, Rajendra et al. 1978, Sun and Liang 1991). In the present study some native Greek Aegilops species of the wider group of genomes C,U which comprises the diploids Ae. umbeUulata U and Ae. caudata var. typica and polyathera C. and tetraploid hybrids Ae. triuncial is UC and Ae. cylindrica DC (genome symbols after Kimber and Tsunewaki 1988) are investigated for their pollen quantitative characters. The results are compared to those of different taxonomical discriminations based on morphological (Zhukovsky 1928. Eig 1929) and cytogenetical data (Kihara 1954. Chennaveeraiah 1960).

Monitoring of Modern Pollen Deposition by Means of Pollen Traps in the Pieria Mountains, Greece: Preliminary Results

A modern pollen deposition monitoring program has been initiated in Greece for the first time. For this purpose six modified Tauber traps (Hicks and Hyvarinen, 1986), were placed on a transect from black pine (Pinus nigra) forest to the tree-line of Scots pine (Pinus sylvestris) in the Pieria mountains.