Ecology is the branch of biology that studies the interactions between living things and their biophysical environment, which includes both living organisms and non-living components. Topics of interest include biodiversity, distribution, biomass and groups of organisms, as well as cooperation and competition within and between species. Ecosystems are a dynamic interaction between the systems of living organisms, the communities that make up them, and the nonliving components of their environment. Ecosystem processes, such as primary production, soil formation, nutrient cycling, and the habitat-building process, regulate the flow of energy and materials through an environment. These processes are supported by organisms with specific life history traits.