29/09 Séminaires Européens: Jennifer McElwain (University College Dublin)
(à ENS amphi L, du 29/09/2014 14:00 au 29/09/2014 15:00)
de 14:00 à 15:00
+33 (0)4 72 43 12 64 33
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Impacts of global warming on plant biodiversity and ecosystem function: A 200 million year old case study form East Greenland
The functioning of modern terrestrial ecosystems has been shaped by an evolutionary legacy of four mass extinction events, multiple geologically driven global warming and cooling events, meteorite impacts, the evolution of advanced plant reproductive grades and plant extinction. Studies from the fossil plant record have revealed that global environmental change of a magnitude similar and greater to that predicted by the year 2100, can result in the collapse of terrestrial ecosystems, resulting in high species level turnover and extinction. In the case of the Triassic-Jurassic boundary (~200 million years ago), ecosystem collapse was preceded by prolonged ecological degradation. A common response of fossil plant communities to global environmental perturbation includes increasing dominance, decreasing evenness, loss of biodiversity and likely reduced productivity. High resolution records of fossil leaves and pollen indicate that ecosystem diversity can be maintained in response to major climatic change via continental scale migration and recruitment of immigrant taxa, yet the functional consequences of these changes are difficult to evaluate. Return of global environmental conditions to pre-excursion norms usually results in a rebound in plant diversity but with drastically altered ecological composition and evidence for ecosystem instability for hundreds of thousands to millions of years. The presentation will focus on the ecological and evolutionary consequences of a global warming event at the Triassic-Jurassic boundary and the feedback effects of plant adaption on fire ecology and marine biodiversity.