Week of 4/13/2020
Please watch the following video: https://www.youtube.com/watch?v=uqEUzgVAF 6g Ecological Succession • Ecological succession: the process of ecological change in an ecosystem where one community is replaced by another community over time *Think back on what constitutes a community* • Two types of succession: – Primary succession: formation of a brand new ecosystem. – Secondary succession: recovery of an old ecosystem. Primary Succession • Primary succession occurs when a community forms in an area that has not been previously occupied Ex. Exposed rock, lava, melted ice, eroded sand Primary Succession • Occurs over a LONG period of time • Pioneer Species = the first organisms to grow in a new environment – Ex. Lichens and mosses in primary succession – These organisms can grow in areas where others cannot – Over time these organisms decompose and release nutrients to form a layer of soil that larger, more complex plants can grow in Primary Succession • Once enough soil has been generated to retain nutrients, small plants, flowers, ferns, and shrubs can begin to grow. Primary Succession • These plants can further break down the rock, allowing more soil to be formed and retained. • The seeds from other plants, even trees become able to grow, and over time large plants become able to inhabit the area. Primary Succession • As new species of plant move in, new animal species become able to inhabit the area. • Organisms growing in each stage may even hinder their own survival, but pave the way for future organisms. Primary Succession • Eventually, a mature community results, in which there is little change in the composition of species. Climax Community = a mature and stable community of plants and animals This is reached towards the END of succession!! Secondary Succession • Secondary succession occurs in an area that was previously occupied by living organisms, but the community was destroyed by a disturbance. Ex. Fire, farming, hurricane, etc. Secondary Succession • Established community is destroyed but soil is still intact therefore it takes less time than primary succession – Pioneer Species for secondary = weeds and grasses
• Process typically begins with weeds and grasses that are able to grow quickly, and proceeds until a Climax Community is reached Think About It • Where in succession you would expect to find organisms and stages that last for short periods of time? Long? – Short periods at the beginning, long at the end • Why might secondary succession tend to occur more quickly than primary? – Because you don’t have to make soil from scratch in secondary succession like you do in primary • What kinds of organisms would you expect to find in an area where disturbances are frequent, or intense? – Pioneer species like lichens, mosses, short grass Succession Summary
Definition Analogy Example Pioneer Result Species
Building a Baking Volcano Mosses and Mature and brand new cookies erupts, lichens stable Primary ecosystem from glacier climax Succession (because from scratch melts community they can scratch; no with flour, make soil!!) soil butter, sugar, etc.
Recovering Baking Forest fire, Weeds and Mature and a previously cookies hurricane, grasses stable Secondary existing with pre- farming (maybe some climax Succession ecosystem made moss and community after a dough lichens, but disturbance; soil is there) soil intact