An ecosystem is a dynamic complex of plant, animal, and microorganism communities and the nonliving environment, interacting as a functional unit. 
An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere). In an ecosystem, each organism has its' own niche, or role to play. The agricultural ecosystem. An ecosystem is defined as all the organisms (animals, plants, microbes) in a certain habitat, plus also the environment that they live in (such as the soil, a pond, or a mountainside). Natural ecosystems usually contain hundreds or thousands of species of organisms and are thus very complex in their functioning. Life In A Pond-Under Water Ecosystem. A pond, a large earth depression where water collects, often has a serene, shallow depth composition to it. The ponds shallowness allows sunlight to penetrate to the bottom, which allows plants to grow. Pond plants either grow entirely underwater or partially on the surface. Pond Ecosystem An ecosystem is a dynamic complex of plant, animal, and microorganism communities and the nonliving environment, interacting as a functional unit. Remember that the organisms living in an ecosystem are broken down into categories: producers, consumers, and decomposers. An ecosystem is a large community of living organisms (plants, animals and microbes) at a particular place or area. The living and physical components are linked together through nutrient cycles and energy flows. Ecosystems can be of any size, but usually they are in particular places. What is an Ecosystem? An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere). In an ecosystem, each organism has its' own niche, or role to play.
http://eschooltoday.com/ecosystems/what-is-an-ecosystem.html http://sustainablesr.org/food/agricultural-ecosystem/ http://www.thewaterpage.com/pond-ecosystem.htm http://www.caryinstitute.org/sites/default/files/public/downloads/curriculum-project/1B3_pond_ecosystem_reading.pdf https://simple.wikipedia.org/wiki/Ecosystem http://eschooltoday.com/ecosystems/what-is-an-ecosystem.html
define pond ecosystem