Paleogene floras of western Greenland and the Faeroes

Oldest records of many modern north-temperate woody angiosperm genera (trees and shrubs) are from the Eocene. However, the precise time and place of origin of individual tree genera, playing important roles in modern temperate forest ecosystems, has largely remained unresolved. One hypothesis about the origin of the temperate woody element in the northern hemisphere was proposed in the late 19th century by Adolf Engler, who suggested that many modern temperate tree genera originated in Arctic areas and migrated southwards in the course of the Cenozoic when global climate cooled. This idea has become unpopular during the second half of the 20th century and many fossil plant taxa from the early Cenozoic of high latitude regions are now considered belonging to extinct groups rather than to modern lineages. The idea of an "arctotertiary element" has been reignited by recent taxonomic revisions of early Cenozoic plant macrofossils from Spitsbergen and slightly younger fossils from Axel Heiberg Island. Pollen and spores are highly conservative plant organs and are diagnostic at the family and genus levels. Nevertheless, for many early Cenozoic localities at high latitudes, no modern palynological investigations, aiming at establishing the systematic and phylogenetic position of dispersed pollen and spores, have been carried out. The main objective of the proposed project is to test the validity of Engler`s (1882) concept of the "arctotertiary element", that is, to determine whether early Cenozoic high latitude floras were the cradle of a number of tree genera that now dominate north-temperate mid-latitude forests. Furthermore, the climatic and ecological signals contained in these fossil floras will be used to reconstruct the environment that may have triggered the evolution of the "arctotertiary element". To achieve this, the systematic affinities of pollen and spores from Paleocene (Danian and Selandian) sediments of western Greenland and Eocene (Ypresian) sediments of the Faeroe Islands will be assessed using modern approaches (light and scanning electron microscopy) to ensure high taxonomic resolution. Macrofossils from the same areas housed in existing museum and university collections will be studied, and new material will be collected in the field. By combining evidence from the revised palyno- and macrofloras, the phylogenetic affinities of the recognized plant taxa will be established in order to determine the proportion of extinct lineages, distantly related to modern taxa, and co-occurring extant genera, representing the "arctotertiary element" in the floras studied. For a number of widespread north -temperate tree genera, it will be established whether they originated in Arctic regions and subsequently migrated southwards, or whether the migration from high-latitude regions to more southern areas represented a secondary migration. The potential role of Arctic areas as source area for younger mid-latitude and modern floras will be assessed.

The Austrian Science Fund (FWF) project Paleogene floras of western Greenland and the Faeroes, hosted at the University of Vienna, investigated in collaboration with an international research team fossil plants that thrived on Greenland 66 to 40 million years ago; the time period following the extinction of the dinosaurs. We recovered and documented an astonishing high diversity of well-known woody plants including alders, beeches, dogwoods, elms, hackberries, hickories, hollies, hornbeams, maples, oaks, sweetgums, walnuts and willows. Most of the plants that grew on Greenland are today found in mid-latitude forests of North America, Europe and Asia. Even more remarkable is the presence of fossils of plants today confined to low-latitudes or the Southern Hemisphere, including representatives of the cape-pondweed-, Chloranthaceae-, citrus-, Clethraceae-, ivy-, Icacinaceae-, palm-tree-, and Winteraceae families. The fossil plant assemblages suggest that 66 to 40 million years ago, Greenland enjoyed a humid and warm climate without any pronounced cold- or particularly dry periods. The vegetation covering the lands, from beaches to hillsides, was extremely diverse. The fossils include aquatic and herbaceous plants linked to lakes, and small woody bushes to short- and extremely high canopy trees shadowing the undergrowth. Even specialised climbers and lianas are represented in the plant fossil record from Greenland. Most remarkably is the discovery of parasitic plants, Loranthaceae, a family of (sub)tropical mistletoes specialized in attaching themselves to host trees and stealing their nutrients by infiltrating their vascular system. The unique mixture of extinct plant lineages and well-known modern lineages, and the varied apparent niches these plants occupied, suggests that a complex ecosystem was already established. Based on the world-wide fossil records of the plants thriving in Greenland, it seems that some of them originated in Arctic areas and then dispersed southwards into the mid-latitudes following global cooling during later times. Others, seem to have originated at low-latitudes, or even in the Southern Hemisphere, and dispersed northwards towards Greenland during the warm phases throughout the end period of the dinosaurs and shortly thereafter. Following further global cooling and as time passed the unique ecosystems gradually changed and the forests that used to thrive there vanished. Much later the land became mostly covered by ice as it is today.