The branch of science known as ecology has to do with the study of the distributions and relationships of living organisms, including humans, within their surrounding environments. Ecologists refer to the system of interdependence between organisms and their environments as the ecosystem, and understanding the dynamics of the world's ecosystems is an important aspect of ecology.
Ecological research occurs on many different levels, from the behavior of microscopic bacteria to the large-scale interactions between thousands of different organisms within a rain forest. Other practical applications of ecological research include the process of evolution and adaptation, the abundance and distribution of species within an ecosystem, the dynamics of energy exchange between organisms and the movement of materials through a living community.
There are various sub-branches of ecology, each dealing with a specific set of research. For example, urban ecology deals with city planning on an environmental scale, while human ecology emphasizes the study of human social interaction within an environment. Other specialties within the wider field of ecology include statistical ecology, marine ecology and vegetation ecology. These and the many other branches of ecology provide important information for managing natural resources, protecting the environment, and understanding the complexity of the world in which we live.