Ecological succession:change in community structure following a disturbance Primary succession(原生演替)begins in a virtually lifeless area where soil has not yet been established. Example:Glacier Bay in Alaska retreating glaciers mosses and lichens are pioneering plant leave moraines堆石. species are next first macroscopic autotrophic bacteria are autotrophs.soil forms first colonizers. gradually 1616 Ecological succession: change in community structure following a disturbance Primary succession Primary succession (原生演替 ) begins in a virtually begins in a virtually lifeless area where soil has not yet been established. lifeless area where soil has not yet been established. Example: Glacier Bay in Alaska Example: Glacier Bay in Alaska retreating glaciers retreating glaciers 冰川 leave moraines leave moraines 堆石. autotrophic bacteria are autotrophic bacteria are first colonizers. first colonizers. mosses and lichens are mosses and lichens are first macroscopic first macroscopic autotrophs. soil forms autotrophs. soil forms gradually gradually pioneering plant pioneering plant species are next species are next