We all know the age-old process of plants capturing the sun's solar energy, creating chemical energy which animals then consume to generate waste etc etc. To add to this we've just read about how it's actually the order or energy 'quality' that is consumed in cyclic process where energy is radiated in, used then radiated out (See Diagram 1.2).
My question is, if the Earth consisted of only plants, would the 'biosphere' still be maintained?
One could argue that we evolved simply to soak up this excess 'ordered' energy that the plants produce; that we in fact are responsible for maintaining the Earth in a stable cyclic system. We consume the plant products and generate more radiative heat that escapes the Earth. In doing so not only are we maintaining the carbon dioxide supply that plants also rely on but also preventing the planet from becoming first an overgrown jungle followed by a dead rock depleted of the necessary supplies for life.
On the other hand we could be considered as parasites that consume the energy wealth of plants; and without our interference that they would be perfectly able to maintain the ordered biosphere of the planet.
Of course considering egotism the former option would be preferrable. Considering evolution however it is doubtless that plants would have become equipped to complete this energy cycle if animals did not exist.
But it comes down to whether this energy cycle is necessary for life to be maintained. Are we actually completing a vital and elegant process or are we providing a redundant service? Would life on Earth still be balanced without the usage of plant matter and the production of animal waste?