Arthur Tansley (July 1935), “The Use and Abuse of Vegetational Concepts”, in Ecology‎^[1] (in English), volume 16, issue 3, archived from the original on 2016-10-06:

Our natural prejudices force us to consider the organisms (in the sense of the biologist) as the most important parts of these systems, but certainly the inorganic “factors” are also parts – there could be no systems without them, and there is constant interchange of the most various kinds within each system, not only between the organisms but between the organic and the inorganic. These ecosystems, as we may call them, are of the most various kinds and sizes. [ from https://en.wiktionary.org/wiki/ecosystem ]