In ancient times people used to worship nature. In their opinion, nature is God. They worshipped mountains, lakes, trees, animals, land and also rocks. They dint know much about the nature. The only thing known to them is nature has power of destroying as well as creating. They knew that they can survive happily only if there is sufficient rainfall. They totally depended on nature. Even though importance of nature recognized by them is absolute, their methods of worshipping are non scientific and blind. Moreover it is very ancient. Even though some continue to believe it even today, defining nature as God is illogical and non-scientific.
So now, if we want to discuss about role of nature today in this world, we can take many facts into consideration which are scientific and proven. Basing on those facts, total properties and features of nature can be explained in different ways. we can consider all the facts belonging to various branches of science. Nature played important role in origin of species by changing its composition several times. Before the origin there was no oxygen in the environment. Sudden evolution of oxygen, minerals from rocks took place which brought variations in organisms, modified anaerobes into aerobes. According to life science theories, there are so many phenomenons like mutation, selection, drift, maintenance of equilibrium which are taking place every day. Nature is playing very important role in all of them. Nature has a capacity of eliminating unwanted organisms simply by killing and changing present organisms by mutating, controlling their births and deaths. It can kill whole species suddenly like how it has lead to the extinction of dinosaurs. It gives protection and at the same time it destroys living beings. It is protecting by presenting itself in several forms like ozone layer – absorbing harmful rays, seawater – absorbing corbon oxides, growing vegetation – providing food, lakes and rivers – providing water source, etc…. It destroys organisms in the form of floods, earthquakes, droughts, volcanoes, etc…
There are certain physical and chemical properties of nature which never change. Whole of scientific discoveries in physics and chemistry fields are nothing but the observations of such properties of nature. Einstein described human beings as small kids observing books in a big library without knowing the name of author and origin of those books. Some of such properties include properties of solids liquids and gases, nature of chemical reactions, motion laws, conservation of energy, etc…they all are simply observations.
So final conclusion is, Nature is everything in this universe excluding man made things which  can exist and function on its own. Nature has certain properties, certain roles and certain functions. Most part of the nature can be created by man now artificially even though its origin is not known inspite of scientific advancement. But properties present in nature cannot be altered.