So we all know that there is a heirarchical structure within our world. Atoms make up molecules. Molecules make cells. Cells make tissues. Tissue make organs. Organs make organ systems. Organ systems make organisms. But It doesn’t stop there!
When we get organisms of the same type, with a common gene pool which can interbreed to produce fertile offspring, we have a species. When they live in a particular place, they are a ‘population’. For example, humans are a species, but each city or town has it’s own population of people. So we have organisms making populations. When many species or populations interact in a given area, it is known as a community (living organisms only). For a community, we could look at a corner of your garden, where bugs and grasses and small mammals like mice are interacting, either through predation (hunting), symbiosis (mutualism, commensalism or parasitism) or competition (for resources). The ecosystem is the sum of all biotic (living) and abiotic (non-living) factors in a particular area. These include animals, plants, wind, rain, sun, soil, and nutrient availability. Common habitats that may be considered to hold a single population of a species are savannas, grasslands or woodlands in a given area. Within these places there would also be a community. When considering the abiotic environment it would also be seen as a whole ecosystem. Communities are often defined by the form of vegetation that is most abundant, such as a “river red gum” community.