Ecosystem
An ecosystem is a functional unit of nature in which living organisms, biotic components interact with one another and with the non-living environment, abiotic components through the flow of energy and cycling of nutrients.
The idea of ecosystem, as definition was given by British ecologist Arthur G Tansley in 1935.
However, the concept of ecology i.e. study of ecosystem(interaction between living and non-living) was Ernst Haeckel in 1866.
Environment
Environment is sum total of everything which is around us in nature like temperature, humidity, sunlight, soil, mountains, valleys, forests, agricultural lands, etc.
The Relationship Between Human Being and Physical Environment
It has been defined as a central theme of geographical thought. Three major approaches emerged to explain this relationship which are known as determinism, possibilism and neo-determinism
Determinism
Natural controlled human activities
Determinism argues that human life, culture, economy and societal development are largely determined by the physical environment. According to this approach factors such as climate, relief, soil, vegetation and location strongly influence human behaviour and development. The founder and supporters of this perspective were Aristotle, Ptolemy, Strabo, Ratzel, EC Semple, Huntington etc. Famous biologist Charles Darwin also believed in the same idea.
Possibilism
Nature provide opportunities, human choose.
Possibilism emerged as a partly reaction against the environmental determinism. It said that the environment sets certain limits and opportunities, but human use culture, technology and knowledge to modify and utilize the environment. Its founder was Vidal-de-la-Blache, a French scholar. Good example to support this argument we have use of technology, aeroplanes, reclamation of land from the sea by Netherland, success of green revolution by using groundwater or irrigation water, etc.
Neo-determinism
Stop and go determinism.
It was given by Griffith Taylor, Australian geographer. His argument was that nature does not completely determine human activities, nor can humans freely do anything they want. Rather nature sets the broad limit within which human development can take place. Taylor compare nature to a traffic. Humans may be able to cultivate semi-arid region using irrigation but excessive exploitation of groundwater shall create problem. Thus the humans should accept the dictate of nature.
Gradually the same idea evolved into the idea of sustainable development.