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.
Ecocentrism
The ecocentric ethic was conceived by Aldo Leopold and recognizes that all species, including humans, are the product of a long evolutionary process and are inter-related in their life processes. The writings of Aldo Leopold and his idea of the land ethic and good environmental management are a key element to this philosophy.
Ecocentrism focuses on the biotic community as a whole and strives to maintain ecosystem composition and ecological processes. The term also finds expression in the first principle of the deep ecology movement, as formulated by Arne Næss and George Sessions in 1984
which points out that anthropocentrism, which considers humans as the center of the universe and the pinnacle of all creation, is a difficult opponent for ecocentrism.