Land Plants in Phanerozoic Biogeochemical Cycles: The Evolving Global Balance

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The genetic evolution and changing geographical ecology of land plants (phytogeography) has been important in the Phanerozoic history of the biogeochemical cycles in which plants massively participate, especially the cycles of carbon, oxygen, nitrogen, phosphorus, and soluble bases. The relationship is bi- directional, with the atmosphere and substrate both shaping, and being shaped by, the evolution and distribution of plants. Support is sought to: (A) Integrate information from numerous disciplines toward more complete and more quantitative descriptions of the mechanisms by which land plants have interacted with the physical and chemical Earth system over Phanerozoic time; (B) Initiate work on a structure to track the spatial distributions of the evolution of the land biota and to deduce the geochemical ramifications of phytogeographic distributions; and (C) Undertake simple experiments on the effects of atmospheric composition, especially O2 level, on the combustion and decomposition of plant tissues. The proposed research will elucidate Phanerozoic trends in the creation, decomposition, and burial of refractory Corg; improve specifications of the effect of atmospheric O2 level on fire, and thereby, on the organization of the land biota and on geochemical balances; improve the representation of the land biota in one dimensional geochemical models; and lay a foundation for incorporation of vegetative cover into a three dimensional linked geochemical-climate model.