Ecological Hierarchy

As organisms interact with their surroundings, they naturally fall into a nested series of organisational levels called the ecological hierarchy (or levels of ecological organisation). The smallest, most basic unit is a single individual organism. A group of individuals of the same species living together in one area forms a population. Multiple populations of different species sharing the same area and interacting with one another form a community. A community together with its non-living (abiotic) surroundings — soil, water, air, sunlight — constitutes an ecosystem, the functional unit where energy flows and nutrients cycle between living and non-living components. Zooming out further, the landscape is a mosaic of interacting ecosystems across a stretch of land, and a biome is an even larger regional grouping of ecosystems that share a similar climate and dominant vegetation type (for example, all the world's tropical rain forests, taken together, form one biome regardless of which continent they sit on). At the very top sits the biosphere — the thin globa …