An ecosystem is a group of animals and plants living in a specific region and interacting with one another and with their physical environment．Ecosystems include physical and chemical components，such as soils，water，and nutrients that support the organisms living there．These organisms may range from large animals to microscopic bacteria．Ecosystems also can be thought of as the interactions among all organisms in a given area；For instance，one species may serve as food for another．People are part of the ecosystems where they live and work．Human activates can harm or destroy local ecosystems unless actions such as land development for housing or business are carefully planned to conserve and sustain the ecology of the area．