Explanation:
The term ecosystem was first coined by Arthur G. Tansley in 1935. He defined the ecosystem 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 was an English botanist who was interested in the interactions between living organisms and their environment.

Tansley's definition of the ecosystem emphasized the importance of studying the interactions between organisms and their physical environment as a whole system, rather than studying them in isolation. He believed that understanding these interactions was essential for understanding the functioning of natural ecosystems.

Tansley's work laid the foundation for modern ecosystem ecology, which is the study of how energy and materials flow through ecosystems, and how the different components of ecosystems interact with one another.

Other Important Contributors to Ecosystem Concept:
- E.P. Odum: He is considered the father of modern ecosystem ecology. He developed the concept of ecosystem energy flow and introduced the idea of trophic levels.
- E. Warming: He was a Danish botanist who introduced the concept of plant communities and their interactions with the environment.
- E. Haeckel: He was a German biologist who first proposed the concept of the biosphere, which refers to the part of the Earth's surface where life exists.

Conclusion:
The term ecosystem was first coined by Arthur G. Tansley in 1935. His definition emphasized the importance of studying the interactions between organisms and their physical environment as a whole system. Tansley's work laid the foundation for modern ecosystem ecology, which is the study of how energy and materials flow through ecosystems, and how the different components of ecosystems interact with one another.