1. A specialist in biogeography, or someone who studies the distributions of living things: Tom's father was a biogeographer who was an expert in plant and animal life in the earth's environment and knew a lot about the biological and historical factors that produced such distributions.
2 .A scientist who studies the spacial distributions of individual organisms in biotic communities: The biotic communities that a biogeographer is concerned with are composed of plants and animals and of ecosystems, or environmental systems, which are associations of biotic communities interacting with their environments.

An ecosystem may be defined and studied at sites in areas ranging from a small pond to a global biome, such as prairies or tropical rain forests.