Ecology is the study of organisms and their relationship to the environment. The field was born in 1866 when German biologist and philosopher Ernst Haeckel (1834-1919) created the precursor to the modern word "ecology" by combining the Greek words oikos, meaning "home," and logos, meaning "study," to create the word "oecology." Haeckel used this word to summarize the concept of natural selection and the struggle for existence that English naturalist Charles Darwin (1809-1882) had outlined in his ground-breaking work on evolution, On the Origin of Species.

In the early twentieth century, even before the modern word ecology had been invented, interest in what is now called plant ecology began to grow. American botanist and ecologist Frederic Clements (1874-1945) and others conceived the idea that plants would develop in an orderly succession of formations from pioneer species to a well-defined and stable group of species called a climax community. Clements...