The environment is constantly changing as a result of human disturbances, like farming and construction, or natural disturbances, like fires, tsunamis, and volcanic eruptions. When these disturbances occur, they often destroy nearby ecological communities. Fortunately, these communities can often recover and establish a new community. In the two pictures below, you see an abandoned community being taken over by plants (left picture) and the establishment of a new plant community 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 once supported life, it is known as succession. Succession is also a word used to describe the transfer of power in government; for example, during royal succession a prince or princess will replace a king or queen. There are two type of succession: primary and secondary (see diagrams below). During primary succession, a new community of organisms is established in a place where none existed before. In contrast, secondary succession describes the replacement of a natural community with a new one due to some type of disturbance. An area of land or water may undergo secondary succession many times; it’s just like cycle. In both types of succession, pioneer species initiate or start the community, which will eventually stabilize. Once the community stabilizes or reaches an equilibrium, it will change very little and be classified as a climax community.

Ecological SuccessionThe process by which organisms occupy a site and gradually change environmental conditions by creating soil, shade, shelter, or increasing humidity

•Primary Succession- occurs when a community begins to develop on a site previously ____________ by living organisms ex. island, new volcanic flowpioneer species- in primary succession, the species that _______ colonizes the new area

• often microbes, mosses and lichens •Secondary Succession- occurs when a community is disrupted and a new one subsequently ___________ at the site

• disruption may be caused by natural catastrophe, human activity•____________ community- in either primary or secondary succession, when a community develops that resists further change •Aquatic Succession-process or succession taking place in a body of __________

•Comparing Primary and Secondary Succcession

•Primary Succession

Primary Succession

Secondary Succession

Secondary Succession

Aquatic Succession