A: Washington, District of Columbia, United States
In 1916 American plant ecologist Frederic E. Clements published from the Carnegie Institution in Washington, D.C. Plant Succession: An Analysis of the Development of Vegetation. This was a seminal work of ecological science, establishing a dynamic model of species succession toward an eventual "climax" equilibrium under the influence of climate and other factors in a given habitat.
"From his observations of the vegetation of Nebraska and the western United States, Clements developed one of the most influential theories of vegetation development. Vegetation cover does not represent a permanent condition but gradually changes over time. Clements suggested that the development of vegetation can be understood as a sequence of stages resembling the development of an individual organism. After a complete or partial disturbance, vegetation grows back (under ideal conditions) towards a mature "climax state," which describes the vegetation best suited to the local conditions. Though any actual instance of vegetation might follow the ideal sequence towards climax, it can be interpreted in relation to that sequence, as a deviation from it due to non-ideal conditions" (Wikipedia article on Frederick Clements, accessed 01-19-2009).