All organisms such as plants, animals, microorganisms and human beings as well as the physical surroundings interact with each other and maintain a balance in nature. All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem.
Thus, an ecosystem consists of biotic components comprising living organisms and abiotic components comprising physical factors like temperature, rainfall, wind, soil and minerals.
In a garden there are many varieties of plants and animals, all of them are interconnected with each other.
Reproduction and other factors are affected by the abiotic components of the ecosystem.
Therefore a garden is an artificial ecosystem because it is man-made.
Ponds, lakes, forests are natural type of ecosystem.