Meso-ecosystems are sub-divided into micro- ecosystems which depart with respect to a certain component (a low land, mountain, or sub-alpine cold broad leaf forest with its fauna). Nano-ecosystems are further small ecosystems which are spatially contained within larger ecosystems and that show a certain individuality of their own.
Natural and Artificial Ecosystems:
Different types of ecosystems like the pond, lake, river, stream, spring, sea, ocean, estuary, forest, grassland, desert, coral reef, cropland, city, etc., differ from each other not only in productivity but also in their species composition. All of them have a similar fundamental plan of their gross structure and function as have been already stated earlier.
However, some ecosystems like pond, lake, river, stream, spring, sea, ocean, estuary, forest, grassland, desert, coral reef, etc., are self-regulating systems without much direct human interference and manipulations, and are called natural ecosystems. On the other hand, the city and cropland ecosystems are man-made (or man-engineered)-ecosystems, so are called artificial ecosystems.
In these ecosystems man plans manipulations (e.g., addition of fertilizers to increase the yield, use of chemicals to control diseases, proper irrigation, etc.) in the physico-chemical environment of the cropland ecosystem to get more food, cloth, timber, medicines and other useful plant products.
There are certain ecosystems which do not contain all the four basic components of ecosystem (i.e., abiotic substances, producers, consumers and decomposers) and they may lack one or more basic components of an ecosystem. Such ecosystems are called incomplete ecosystems (Southwick, 1976).
For example, certain incomplete ecosystems such as abyssal depths of the sea and caves lack producers but contain only consumers and decomposers. As in the realm of complete darkness green plants cannot survive.