Systems Ecology is the field of study that arose from the union of General Systems Theory and ecology. General Systems Theorists observe that the same laws and principles have been separately derived in many disciplines through isolated study of systems in those fields; whereas, these same laws and principles have already been discovered and are commonly used in other disciplines. This is wasteful duplication that prevents a holistic understanding of natural phenomena. When ecology is defined broadly to include multiple scales of biotic and abiotic processes from the realms of bacteria to the scale of environment and humanity within landscapes, the application of General Systems Principles within ecological studies becomes a powerful way to increase our knowledge and understanding of the dynamics of all natural phenomena observed within Earth's systems.
I consider that talking about Systems Ecology is a way to promote this idea, this is why I also use this term, insisting on the principles of Systems Theory and especially on the notion of "emerging properties", that I like to illustrate with the recycling processes.