The effects of terrestrialization on marine ecosystems: the fall of CO2
Published:January 01, 2010
Paul K. Strother, Thomas Servais, Marco Vecoli, 2010. "The effects of terrestrialization on marine ecosystems: the fall of CO2", The Terrestrialization Process: Modelling Complex Interactions at the Biosphere–Geosphere Interface, M. Vecoli, G. Clément, B. Meyer-Berthaud
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The rise of land plants during the early Palaeozoic had profound effects upon subsequent Earth history and evolution. The sequestration of standing biomass and carbon burial caused a primary shift in the distribution of active carbon within the biosphere and surficial Earth systems. This manifested itself in a dynamic decline in pCO2 during Silurian–Devonian time, affecting both terrestrial and marine ecosystems. We examined first-order correlations between terrestrialization and pCO2 by comparing the GEOCARB III data with time-constrained fossil events in the early evolution of land plants. We compared the same GEOCARB III data with the species/genus richness of lower Palaeozoic acritarchs. The correlation between the rise of woody plants and pCO2 is built into the GEOCARB model for the Late Devonian and later, but pCO2 begins to decline in the Cambrian long before the origin of woody trees (lignophytes). The influence of early phases in plant evolution may be seen in a two-stage pCO2 decline corresponding to fossil evidence for the origin of thalloid bryophytes in the Middle Cambrian and the origin of tracheophytes near the Ordovician–Silurian boundary. The decline of the acritarchs shows a highly correlated lag of about 10 Ma with respect to the pCO2 decline. The relation between pCO2 and acritarch species richness suggests a tight coupling between the evolution of the marine phytoplankton and atmospheric CO2, supporting previous suggestions that pCO2 was a significant causal factor in the near extinction of acritarchs by the end of the Devonian.
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The Terrestrialization Process: Modelling Complex Interactions at the Biosphere–Geosphere Interface
The invasion of the land by plants (‘terrestrialization’) was one of the most significant evolutionary events in the history of life on Earth, and correlates in time with periods of major palaeoenvironmental perturbations. The development of a vegetation cover on the previously barren land surfaces impacted on the global biogeochemical cycles and the geological processes of erosion and sediment transport. The terrestrialization of plants preceded the rise of major new groups of animals, such as insects and tetrapods, the latter numbering some 24 000 living species, including ourselves. Early land-plant evolution also correlates with the most spectacular decline of atmospheric CO2 concentration of Phanerozoic times and with the onset of a protracted period of glacial conditions on Earth. This book includes a selection of papers covering different aspects of the terrestrialization, from palaeobotany to vertebrate palaeontology and geochemistry, promoting a multidisciplinary approach to the understanding of the co-evolution of life and its environments during Early to Mid-Palaeozoic times.