Towards a new picture of the ‘Baltic amber forest’  flora, habitat types, and palaeoecology Dissertation zur Erlangung des mathematisch-naturwissenschaftlichen Doktorgrades "Doctor rerum naturalium" der Georg-August-Universität Göttingen im Promotionsprogramm Geoscience der Georg-August University School of Science (GAUSS) vorgelegt von Eva-Maria Sadowski aus Lüdenscheid Göttingen, 2017 Betreuungsausschuss Prof. Dr. Alexander Schmidt, Georg-August-Universität Göttingen, Abteilung Geobiologie, Arbeitsgruppe "Evolution der Landpflanzen und Entwicklung der terrestrischen Ökosysteme" Dr. Leyla J. Seyfullah, Georg-August-Universität Göttingen, Abteilung Geobiologie, Arbeitsgruppe "Evolution der Landpflanzen und Entwicklung der terrestrischen Ökosysteme" Dr. Lutz Kunzmann, Senckenberg Naturhistorische Sammlungen Dresden, Sektion Paläobotanik Mitglieder der Prüfungskommission Referent: Prof. Dr. Alexander Schmidt, Abteilung Geobiologie, Arbeitsgruppe "Evolution der Landpflanzen und Entwicklung der terrestrischen Ökosysteme", Georg-August- Universität Göttingen Korreferent: Dr. Lutz Kunzmann, Sektion Paläobotanik, Senckenberg Naturhistorische Sammlungen Dresden Prof. Dr. Hermann Behling, Abteilung Palynologie und Klimadynamik, Georg- August-Universität Göttingen PD Dr. Dirk Gansert, Abteilung Plfanzenökologie und Ökosystemforschung, Georg- August-Universität Göttingen Prof. Dr. Jouko Rikkinen, Finnish Museum of Natural History, University of Helsinki Dr. Leyla Seyfullah, Abteilung Geobiologie, Arbeitsgruppe "Evolution der Landpflanzen und Entwicklung der terrestrischen Ökosysteme", Georg-August- Universität Göttingen Tag der mündlichen Prüfung: 14.06.2017 i Content Appendices ................................................................................................................. iv List of tables and figures ............................................................................................ v Summary ..................................................................................................................... 1 1. Introduction ............................................................................................................ 3 1.1. What is amber? ...................................................................................................... 3 1.2 Amberization and the formation of an amber deposit ........................................... 3 1.3 Amber deposits worldwide and in the Baltic area ................................................. 4 1.4 Amber classification .............................................................................................. 5 1.5 Abundance and formation of inclusions from Baltic amber ................................. 6 1.6 The Baltic amber mysteries ................................................................................... 9 1.6.1 Geographical location of the ‘Baltic amber forest’ and the age of Baltic amber .................................................................................................................. 9 1.6.2 Putative source plants of Baltic amber .............................................................. 11 1.6.2.1 Morphological-anatomical implications from Baltic amber inclusions ........ 15 1.6.2.2 Chemical analyses for inferring the Baltic amber tree ................................... 15 1.6.2.3 Succinic acid – key component or diagenetic product? ................................. 16 1.6.3 The enigmatic ‘Baltic amber forest’ .................................................................. 17 2. Aims of this thesis ................................................................................................ 20 3. Material and methods .......................................................................................... 21 3.1 Specimens investigated......................................................................................... 21 3.2 Preparation, microscopy and imaging .................................................................. 21 3.3 Permanent preparation .......................................................................................... 22 4. Plant inclusions: their contribution to the understanding of vegetation, palaeoecology and habitat structure of the ‘Baltic amber forest’ ........................ 24 4.1 Conifers ................................................................................................................ 24 4.1.1 Unexpected conifer diversity of the Baltic amber flora .................................... 24 4.1.2 Indeterminable conifers – challenges and preliminary results .......................... 27 4.1.3 Conifer inclusions revise our understanding of the Baltic amber source area .. 40 ii 4.1.4 New candidates for the Baltic amber source plant ............................................ 41 4.2 Angiosperms ......................................................................................................... 46 4.2.1 Angiosperm diversity of the Baltic amber flora ................................................ 46 4.2.2 Angiosperm inclusions and their potential as palaeoecological key taxa .......... 54 4.3 Indicators for life forms and microhabitat complexity ......................................... 58 5. What is new about the picture of the ‘Baltic amber forest’? ........................... 64 5.1. Habitat heterogeneity and stratification of the ‘Baltic amber forest’ .................. 64 5.2. Palaeoclimatic estimations of the ‘Baltic amber forest’ ...................................... 66 5.3. Wheeler’s dilemma, the Eridanos river and the quest for mountains in the ‘Baltic amber forest’ ................................................................................................... 68 5.4. Geoflora concept – does it apply to the ‘Baltic amber forest’? ........................... 72 6. Conclusions and outlook ...................................................................................... 75 7. Acknowledgements ............................................................................................... 76 8. References ............................................................................................................. 77 Versicherung ............................................................................................................... 97 Declaration about own contributions to the papers included in this thesis ................. 98 Appendices ................................................................................................................ 101 iii Appendices [1] Seyfullah, L. J., E.-M. Sadowski, and A. R. Schmidt. 2015. Species-level determination of closely related araucarian resins using FTIR spectroscopy and its implications for the provenance of New Zealand amber. PeerJ 3:e1067, doi: 10.7717/peerj.1067. [2] Kettunen, E., H. Grabenhorst, C. Gröhn, H. Dörfelt, E.-M. Sadowski, J. Rikkinen, and A. R. Schmidt. 2015. The enigmatic hyphomycete Torula sensu Caspary revisited. Review of Palaeobotany and Palynology 219:183-193. [3] Sadowski, E.-M., A. R. Schmidt, L. Kunzmann, C. Gröhn, and L. J. Seyfullah. 2016a. Sciadopitys cladodes from Eocene Baltic amber. Botanical Journal of the Linnean Society 180:258-268. [4] Sadowski, E.-M., A. R. Schmidt, P. J. Rudall, D. A. Simpson, C. Gröhn, J. Wunderlich, and L. J. Seyfullah. 2016b. Graminids from Eocene Baltic amber. Review of Palaeobotany and Palynology 233:116-168. [5] Sadowski, E.-M., A. R. Schmidt, L. J. Seyfullah, and L. Kunzmann. 2017a. Conifers of the ‘Baltic amber forest’ and their palaeoecological significance. Stapfia (in press). [6] Sadowski, E.-M., L. J. Seyfullah, C. A. Wilson, C. L. Calvin, and A. R. Schmidt. 2017b. Diverse early dwarf mistletoes (Arceuthobium), ecological keystones of the Eocene Baltic amber biota. American Journal of Botany 104: 1-25. doi:10.3732/ajb.1600390. iv List of tables and figures Tables Tab. 1: Classification system for ambers ......................................................................... 6 Tab. 2: Suggested source plants of Baltic amber ........................................................... 14 Tab. 3: Perceptions of the ‘Baltic amber forest’. ........................................................... 19 Tab. 4: Baltic amber collections examined for this thesis ............................................. 21 Tab. 5: Updated list of coniferous inclusions from Baltic amber .................................. 25 Tab. 6: Preliminary results of morphotypes of cupressaceous twig fragment inclusions from Baltic amber .......................................................................................... 31 Tab. 7: Preliminary results of cupressaceous pollen cone types from Baltic amber ..... 36 Tab. 8: Arguments for and against different suggested source trees of Baltic succinite .......................................................................................................................... 45 Tab. 9: Current list of angiosperms from Baltic amber ................................................. 47 Tab. 10: Angiosperm families described from Baltic amber and their suggested geographical affinity, after Czeczott (1961). .................................................................. 55 Figures Fig. 1: Cupressaceous twig fragment inclusions from Baltic amber, assigned to shoot type 1 ............................................................................................................................... 30 Fig. 2: Cupressaceous twig fragment inclusion from Baltic amber, assigned to shoot type 2 ............................................................................................................................... 33 Fig. 3: Cupressaceous twig fragment inclusions from Baltic amber, assigned to shoot type 3 ............................................................................................................................... 34 Fig. 4: Cupressaceous pollen cone inclusions from Baltic amber, assigned to pollen cone type 1 to 3 ............................................................................................................... 38 Fig. 5: A carnivorous leaf inclusion from Baltic amber and extant Roridulaceae ......... 49 Fig. 6: Inclusions of fagaceous male inflorescences from Baltic amber ........................ 51 Fig. 7: Inclusions of ericoid twig framgents from Baltic amber .................................... 53 Fig. 8: Extant dwarf mistletoe species (Arceuthobium spp., Viscaceae) from the United States ................................................................................................................... 60 v Summary Amber is fossilized resin that was excreted by conifers or angiosperms. Plant and animal remains which got caught inside of these ancient resin flows are called ‘inclusions’ and are often preserved with high fidelity. Amber deposits which are remarkably rich in inclusions mainly occur in Cretaceous and Cenozoic sediments. The Eocene Baltic amber is a prominent example which constitutes the largest amber deposit worldwide and is famous for its plenitude of inclusions that mainly comprise arthropod taxa. This thesis, however, focuses on plant inclusions from Baltic amber, which are rare, and less studied than the arthropod inclusions. Despite their rareness, plant inclusions are significant for the reconstruction of the palaeoecosystem from which the amber derives, the so-called ‘Baltic amber forest’. Up to now, knowledge about the ‘Baltic amber forest’ is mainly based on historic descriptions of plant inclusions from the 19th century and on the interpretation of animal inclusions. Contradictory pictures of the ‘Baltic amber forest’ exist, ranging from tropical lowland rainforests with neighbouring subtropical to temperate mountain forests to steppe forests and pure, dense conifer stands that only intermingled with angiosperm trees along their margins. The topography of the Baltic amber source area is mainly interpreted as mountainous, but also theories about a plain landscape exist. Further debates are related to the age of Baltic amber, as well as the locality of its source forests and its botanical origin. These questions were summarized as ‘Baltic amber mysteries’. The primary focus of this thesis is to achieve a new picture of the ‘Baltic amber forest’ by predominantly using plant inclusions. Amber inclusions from museum and private collections were used to revise described historic specimens and to identify undescribed plant taxa from Baltic amber. Identified plant taxa were then compared to their fossil and extant analogues. This comparison served to reconstruct the potential palaeoecology of plant taxa, as well as their habitat preferences and palaeoclimatic requirements. With this information, plant diversity, habitat types and their structure were reconstructed, thus synthesising a new picture of the ‘Baltic amber forest’. In this thesis, ten conifer genera were identified from Baltic amber: Calocedrus, Quasisequoia and Taxodium (Cupressaceae), Cupressospermum (Geinitziaceae), Abies, Cathaya, Nothotsuga, Pseudolarix and Pinus (Pinaceae), and Sciadopitys (Sciadopityaceae). The diversity of Cupressaceae is actually higher, since three morphological complexes of Cupressaceous twig fragments and pollen cones were also classified. The majority of all identified conifers has not been verified from Baltic amber before; thus, new candidates for a Baltic amber source plant should be restudied. In addition, newly discovered or revised angiosperm inclusions confirm the presence of Poaceae, Cyperaceae (Rhynchospora), Roridulaceae, Myricaceae (Comptonia), Viscaceae (six species of Arceuthobium), Ericaceae (Cassiope or Calluna), and Fagaceae (quercoid and castaneoid taxa) in the 1 ‘Baltic amber forest’. The named conifers and angiosperms allowed the reconstruction of several habitat types with their respective plant communities from the Baltic amber source area: coastal lowland swamps under brackish-water influence, raised bog habitats, non-brackish inundated back swamps and riparian forests, non-inundated mixed-mesophytic angiosperm-conifer forests with both open habitat patches (such as meadows) and canopy gaps. Moreover, different life forms could be reconstructed, such as parasitic (dwarf mistletoes, Arceuthobium) and carnivorous (Roridulaceae) plants. Previous studies about ferns, bryophytes, liverworts, fungi and lichens from Baltic amber were also considered in the interpretation of the microhabitats of the ‘Baltic amber forest’. They indicated complex and highly diverse communities with epiphytic, terrestrial, saprophytic and parasitic components. From a palaeobotanical perspective, there is neither evidence of a (sub)tropical ‘Baltic amber forest’, nor of an altitudinal stratification of the source area. This is supported by previous geological studies of the Baltic amber deposit, which suggest a local amber formation and deposition in the Baltic region during the late Eocene. No orogenic events took place in the Baltic region, precluding the presence of mountains in the Baltic amber source area. Comparisons of the Baltic amber flora with fossil assemblages from the central European Palaeogene showed clear differences to (sub)tropical fossil floras. Instead the Baltic amber flora indicates a warm-temperate palaeoclimate with affinities to the extant warm-temperate to temperate floras of East Asia and North America. The thorough analyses of available plant inclusions from Baltic amber reveal a heterogeneous mosaic-like landscape of the Baltic amber source area in a coastal setting. This heterogeneity allowed the existence of diverse animal and plant taxa with different habitat preferences in close proximity to each other. 2