Ecosystem: biological community of interacting organisms and their physical environment.
Habitat: environmental area that is inhabited by a particular species of animal, plant or other type of organism.
Niche: the position or function of an organism in a community of plants and aniamls. The particular area within a habitat occupied by an organism.
Population: all the same organisms living in the same area.
Community: a number of different organisms from populations that interact in the same area. Vary in species.