Population, community, and ecosystem ecologists study structure and process. How

A population ecologist might study the distribution and abundance, rates of population growth, rates of reproduction, or dispersal of a particular species in the forest, such as birch. A community ecologist would be more focused on patterns of species diversity, food web structure, and how keystone species or physical disturbance influences species diversity and composition. An ecosystem ecologist studying the same forest would be concerned with processes such as primary production, energy flow, and nutrient cycling (integration of the species with their abiotic environment).