The environment is constantly changing as a result of human disturbances, likefarming and construction, or natural disturbances, like fires, tsunamis, and volcaniceruptions. When these disturbances occur, they often destroy nearby ecologicalcommunities. Fortunately, these communities can often recover and establish anew community. In the two pictures below, you see an abandoned communitybeing taken over by plants (left picture) and the establishment of a new plantcommunity on Mount St. Helens following a volcanic eruption (right picture).
Succession – Changes in Ecosystem
When living organisms begin to invade an area without life or an area that oncesupported life, it is known as succession. Succession is also a word used to describethe transfer of power in government; for example, during royal succession a prince orprincess will replace a king or queen. There are two type of succession: primary andsecondary (see diagrams below). During primary succession, a new community oforganisms is established in a place where none existed before. In contrast, secondarysuccession describes the replacement of a natural community with a new one due tosome type of disturbance. An area of land or water may undergo secondarysuccession many times; it’s just like cycle. In both types of succession, pioneer speciesinitiate or start the community, which will eventually stabilize. Once the communitystabilizes or reaches an equilibrium, it will change very little and be classified as aclimax community.
Ecological SuccessionThe process by which organisms occupy a site and gradually change environmentalconditions by creating soil, shade, shelter, or increasing humidity
•Primary Succession- occurs when a community begins to develop on a sitepreviously ____________ by living organisms ex. island, new volcanic flowpioneer species- in primary succession, the species that _______ colonizes the newarea
•often microbes, mosses and lichens
•Secondary Succession- occurs when a community is disrupted and a new onesubsequently ___________ at the site
•disruption may be caused by natural catastrophe, human activity
•____________ community- in either primary or secondary succession, when acommunity develops that resists further change
Primary Succession
Secondary Succession
Secondary Succession
Aquatic Succession
