Ecology is a broad science which can be subdivided into major and minor sub-disciplines. The major sub-disciplines include (in a nested series from the smallest to the largest in scope):

• Behavioral ecology, which studies the ecological and evolutionary basis for animal behavior, and the roles of behavior in enabling animals to adapt to their ecological niches;
• Population ecology (or autecology), which deals with the dynamics of populations within species, and the interactions of these populations with environmental factors;
• Community ecology (or synecology) which studies the interactions between species within an ecological community;
• Landscape ecology, which studies the interactions between discrete elements of a landscape;
• Ecosystem ecology, which studies the flows of energy and matter through ecosystems;
• Global ecology , which looks at ecological questions at the global level, often asking macroecological questions.

Ecology can also be sub-divided on the basis of target groups:

• animal ecology , plant ecology , insect ecology ;

or from the perspective of the studied biomes:

• arctic ecology (or polar ecology ), tropical ecology , desert ecology

(temperate zone ecology could also exist as a distinct sub-field, but ecology as a whole has an overwhelmingly temperate bias, so the sub-field is redundant).

Other specialized branches of ecology include:

• marine ecology , and aquatic ecology;
• Applied ecology, the practice of employing ecological principles and understanding to solve real world problems (includes agroecology and conservation biology);
• chemical ecology, which deals with the ecological role of biological chemicals used in a wide range of areas including defense against predators and attraction of mates;
• ecological succession;
• conservation ecology;
• systems ecology and biogeochemistry which focus on the flow of energy and nutrients within and among ecological units;
• ecophysiology which studies the relations between a single type of organism and the factors of its environment;
• ecotoxicology , which looks at the ecological role of toxic chemicals (often pollutants, but also naturally occurring compounds);
• evolutionary ecology or ecoevolution which looks at evolutionary changes in the context of the populations and communities in which the organisms exist;
• fire ecology , which looks at the role of fire in the environment of plants and animals and its effect on ecological communities.
• macroecology;
• molecular ecology, which attempts to address ecological questions at the molecular level, usually through by looking at DNA or allozymes;
• paleoecology, which seeks to understand the relationships between species in fossil assemblages, and in so doing gain insight into the way these species might have been shaped by their interactions with other species;
• restoration ecology , which attempts to understand the functioning of ecosystems in order to restore human-impacted sites;
• soil ecology and microbial ecology;
• theoretical ecology is a broad term which generally refers to any approach to ecological questions which are addressed primarily in theoretical terms, usually through simulation and modelling;
• urban ecology.

Ecology also plays important roles in many inter-disciplinary fields:

• ecological design and ecological engineering.
• ecological economics.
• human ecology and ecological anthropology .
• social ecology, ecological health and environmental psychology .

Finally, ecology has also inspired (and lent its name to) other non-biological disciplines such as

• industrial ecology.
• software ecology and information ecology.