From an ecological point of view, Earth is made of the hydrosphere, the lithosphere, the geosphere and the biosphere. An assemblage of natural communities and species, within areas of ecological potential based on soil, climate and topography parameters are called ecoregions, and consitute a basic element in ecology.
Much of ecological research is concerned with the distribution and abundance of organisms and how the distribution and abundance of organisms is influenced by features of the environment. Not only are organisms influenced by the environment but the presence of organisms actually modifies the environment, in a complex two-way interaction.
Ecology includes many sub-disciplines including theoretical ecology, applied ecology, behavioral ecology, macroecology, systems ecology, ecosystems ecology, community ecology, population ecology, landscape ecology, conservation ecology, soil ecology, paleoecology, microbial ecology, ecoevolution and agroecology.
Ecology also plays important roles in the inter-disciplinary fields of ecological economics, ecological health and ecological design.
An interesting, but controversial, idea in ecology studies is the Gaia theory.
For access to a database of ecology as it relates to economic development see ELDIS.