The gradual replacement of one community by another is called ecological succession . When a community begins where another community already exists, secondary succession occurs. For example, a(n) forest can gradually replace a farm. When a community begins where there are few, if any, living things, primary succession occurs. Such places include land swept clean by a volcanic eruption or forest fire. The first species to be living in an otherwise lifeless area is a(n) pioneer species. A new community is also known as a(n) pioneer community.