An ecosystem is a natural unit consisting of all plants, animals and micro-organisms(biotic factors) in an area functioning together with all of the non-living physical (abiotic) factors of the environment.Christopherson, RW (1996) Geosystems: An Introduction to Physical Geography. Prentice Hall Inc.

Overview

Central to the ecosystem concept is the idea that living organisms are continually engaged in a set of highly interrelated relationships with every other element constituting the environment in which they exist. Eugene Odum, one of the founders of the science of ecology, stated: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (ie: exchange of materials between living and nonliving parts) within the system is an ecosystem."Odum, EP (1971) Fundamentals of ecology, third edition, Saunders New York The human ecosystem concept is then grounded in the deconstruction of the human/nature dichotomy, and the emergent premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.

Ecosystems can be bounded and discussed with tremendous variety of scope, and describe any situation where there is relationship between organisms and their environment. If humans are part of the organisms, one can speak of a 'human ecosystem'. As virtually no surface of the earth today is free of human contact, all ecosystems can be more accurately considered as human ecosystems, or more neutrally as human-influenced ecoystems.

Examples of ecosystems

• Aquatic ecosystem
• Chaparral
• Coral reef
• Desert
• Greater Yellowstone Ecosystem

• Human ecosystem
• Large marine ecosystem
• Littoral zone
• Marine ecosystem
• Rainforest

• Savanna
• Subsurface Lithoautotrophic Microbial Ecosystem
• Taiga
• Tundra
• Urban ecosystem

Biomes

Classification