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Towards the development of a Palaeo UV-B proxy from fossil land plants
18/12/2004 00:00 | Durée 00:14:15

Intervenants : B.H. Lomax , Department of Animal and Plant Sciences, University of Sheffield, UK .  

Changes in atmospheric oxygen, major volcanic eruptions and impact events have the potential to induce short- and long-term changes to the stratospheric ozone layer. However, detecting the interaction between these events and the expected increase in terrestrial UV-B flux has proved elusive. Recent laboratory investigations suggest that the spores and pollen of land plants may respond to variations in the UV-B radiation by increasing investment in UV-B screening pigments. However, it is not known if this response is replicated in natural settings. Here, we report an increase in UV-B protecting pigments from the spores of plants growing in South Georgia (54° 20'S, 36° 40'W) and exposed to a progressive thinning of the Antarctic ozone hole since the 1950s. Our data records a strong three fold linear increase in the concentration of UV-B protecting pigments of Lycopodium. magellanicum spores in response to a 14% thinning of the ozone column. Our results were obtained using high temperature FTIR analysis of sporopollenin, a decay-resistant biomacromolecule readily preserved in the fossil record. Therefore, this newly identified response of extant plants to modern day climate change offers the exciting possibility for the development of a potential tool to investigate palaeo changes in stratospheric ozone layer and UV-B flux.