Give two examples of artificial or man made ecosystems. List the salient features by which they differ from natural ecosystems. 

Explanation

Aquarium and farm house, are artificial or man made ecosystem. In artificial ecosystem biotic and abiotic component are maintained artificially like cleaning, 'feeding and supply of oxygen to fishes in aquarium and irrigation in crop or farm house. 
While abiotic and biotic component of natural ecosystem are maintained naturally like nutrient cycle, self sutainability, prevention of soil erosion, pollutant absorption and reduction of threat to global warming (ecological servicer), etc.