Paper No. 5
Presentation Time: 9:05 AM
TIPPING POINTS, TAPHONOMY AND GLOBAL BIOGEOCHEMICAL FEEDBACKS: A REVIEW OF THE TRIASSIC–JURASSIC MASS EXTINCTION INTERVAL FROM ASTARTEKLøFT, EAST GREENLAND
Our understanding of the complex sequence of environmental and biological changes that occurred during the transition from the Triassic to Jurassic period in Earth history has blossomed over the past decade. Insights from terrestrial basins around the globe have matched those from marine sequences providing a truly earth system perspective on the pace and nature of climatic and atmospheric change and how biological systems responded. Triassic–Jurassic research has also provided fundamental data to test modern ecological theory on the relationship between biodiversity –productivity–stability, ecosystem resilience, limits of phenotypic and physiological plasticity, tipping points, invasive species and ecosystem function to name a few. Palaeobotanical, geochemical and sedimentological investigation of Kap Stewart Group strata, Astartekloft, East Greenland have shown that the Triassic-Jurassic interval was characterized by super greenhouse conditions forced by elevated CO2 and punctuated by episodes of high SO2. The nature of biotic response to such environmental perturbations was found to be dependent on the palaoobotanical archive studied and the unique set of taphonomic factors associated with the pollen and spore versus macrofossil leaf records. Plant communities responded to environmental change at Astartekløft with a sudden decrease in generic diversity and evenness, high species-level extinction and turnover but long term persistence of the majority of plant families which contrasts sharply with coeval faunal records. Physiological and physiognomic responses of terrestrial vegetation to TJ environmental change likely had an equally significant impact on ecosystem function as biodiversity loss, via their effect on the hydrological cycle and fire ecology. These and other research findings from Astartekløft, East Greenland will be explored and their relevance in the context of current global challenges, such as climate change, tipping points and ecosystem services will be discussed.