Plant Biodiversity and Responses to Elevated Carbon Dioxide

The general assumption, in the first phase of elevated carbon dioxide (CO2) research, was that increasing atmospheric CO2 concentration would act as a fertilizer for plant systems. Under this “large-plant-scenario” (Fig. 9.1), increased photosynthesis at elevated CO2 would lead to higher plant biomass which would induce a negative atmospheric feedback loop that would offset anthropogenic carbon (C) emissions. A second general assumption in early research was that the effects of elevated CO2 on plant community structure could be predicated using a C-based perspective with clear “winners” and “losers” based on species’ ability to take advantage of the increased atmospheric CO2 concentration (e.g., plant with C3 vs. C4 photosynthetic pathways). The reality unveiled by a decade of research proved more complex and the “large plant scenario” largely untenable.