ABSTRACT

This chapter deals with the plant CO2-fixation processes that, in a variable environment, underpin primary production, interact with numerous environmental cycles, and need to be managed and/or supplemented to enable sustainable human habitation of Earth. CO2 is the primary carbon source for the organic compounds of terrestrial ecosystems. It was discovered in the eighteenth century as “fixed air” released when plant material, for example, was combusted. The process of carbon assimilation, often referred to as “CO2 fixation,” underpins the primary production of biomass. The carboxylase activity of rubisco is greater than its oxygenase activity, but overall fixation depends on the CO2:O2 ratio at the active site. The effects of sustained increases in CO2 concentration on plant growth exemplify why an understanding of the effects of spatial and temporal variation in interacting abiotic factors is vital to understanding plant–environment interactions. CO2 fixation in multicellular plants is the primary provider of biomass in terrestrial ecosystems.