The Effects of Spatial Scale on Vegetation Dynamics across the Triassic – Jurassic Boundary in East Greenland

The Triassic/Jurassic boundary (TJB) is marked by the third greatest ecological catastrophe in the history of life, with the loss of 23% of marine families and 22% of terrestrial families. This mass extinction event coincided with major environmental upheaval, highlighted by a perturbation of the global carbon cycle. Analyses of stomatal indices suggest a fourfold increase in paleoatmospheric carbon dioxide levels across the TJB, and results of modeling studies imply a maximum 16˚C regional climatic warming. Local studies of the plant macrofossil record in the Jameson Land region of East Greenland have provided evidence of ecosystem instability millions of years prior to, and following, peak extinction at the TJB, demonstrating that terrestrial vegetation was profoundly disrupted by climatic changes around the TJB. It is presently unclear however, exactly how these changes scale-up to the wider Jameson Land region. To explore this issue we have undertaken a palynological analysis of the TJB in East Greenland. Samples have been collected from the Kap Stewart Group at Astartekløft, Jameson Land and we have employed Quaternary-style analytical techniques incorporating abundance data. The vegetation history of the East Greenland region, as recorded by fossil pollen, has been directly compared with paleoecological studies based on macrofossil leaves to build a more comprehensive picture of regional versus local vegetation change at the Triassic – Jurassic transition. It has been demonstrated previously that the ecological and taxonomic effects of ancient biotic crises in the marine ecosystem are decoupled. Ecological changes among terrestrial plant associations have been set against taxonomic turnover across the TJB in East Greenland, to examine whether a similar decoupling is apparent among the terrestrial flora.