ABSTRACT
Organisms in ecosystems are roughly divided into three groups with very distinctive functions: producers (e.g. plants), consumers (e.g. birds) and decomposers (e.g. dung beetles). In physiological terms producers perform anabolic functions, consumers metabolic functions and decomposers katabolic functions. In ecosystems terms human beings are involved in metabolism so they are consumers. Of course people produce goods like cars and take them apart again when they are no longer useful. Yet car producers essentially transform raw materials and energy and the same holds for car drivers and car scrappers. During the human production-use-recycle and waste-handling phases, environmental resources like metal, water, space and fuel maintain their quantity but change quality.
