Ecosystem assembly and terrestrial carbon balance under elevated CO2

Research aimed at understanding how the global carbon balance will change with elevated CO2 has largely ignored the responses of individual species and genotypes. Yet, plant traits strongly influence the biogeochemical cycling of carbon. Here, we illustrate how differences in inter- and intraspecific responses to elevated CO2 affect not only physiology and growth, but also higher order biotic interactions and lifetime fitness, ultimately leading to new ecosystem assemblages. We assert that the unique combination of inter- and intraspecific traits in these ecosystem assemblages ultimately determine how ecosystems respond to elevated atmospheric CO2. Thus, the identity of species and genotypes in an ecosystem is a crucial element to consider in forecasts of global carbon balance.