Ecosystem
The term ecosystem was first used in 1935 in a publication by British ecologist Arthur Tansley. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as "The whole system, ... including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment". Tansley regarded ecosystems not simply as natural units, but as "mental isolates". Tansley later defined the spatial extent of ecosystems using the term ecotope.
Stephen Alfred Forbes
Stephen Alfred Forbes (May 29, 1844 – March 13, 1930) was the first chief of the Illinois Natural History Survey, a founder of aquatic ecosystem science and a dominant figure in the rise of American ecology. His publications are striking for their merger of extensive field observations with conceptual insights. Forbes believed that ecological knowledge was fundamental for human well being. Forbes was important to the development of ecological theory. He was acknowledged by the National Academy of Sciences as "the founder of the science of ecology in the United States".