Agricultural ecosystems (or agro-ecosystems) are those "ecosystems that are used for agriculture" in similar ways, with similar components and similar interactions and functions. Agro-ecosystems are determined by three sets of factors: the genetic resources, the physical environment and the human management practices, which exhibit genetic, spatial and temporal variation, as well as by their interactions.
Agro-ecosystems may be identified at different levels or scales, for instance, a field/crop/herd/ pond, a farming system, a land use system or watershed. These can be aggregated to form a hierarchy of agro-ecosystems. Agro-ecosystems comprise polycultures, monocultures, and mixed systems, including crop-livestock systems, agroforestry, agro-silvo-pastoral systems, aquaculture as well as rangelands, pastures and fallow lands. Their interactions with human activities, including socio-economic activity and sociocultural diversity are determinant.