FTTS F04 Paul’s Lecture 11/8/04 Page 1 of 3Succession- Central concept in ecologyDefinitionLegacy DistributionsCurrent species could be adapting to changing conditions that aren’t readilyapparent.Current condition of a soil does not necessarily reflect the current ecosystemThree major categories of change1. 2. 3. Disturbance is a constant in most ecosystemsVary in severityVary in size and frequencyDisturbance/succession are two sides of the same coinPrimary successionSecondary succession“Climax Community”Species distributions within ecosystemsFTTS F04 Paul’s Lecture 11/8/04 Page 2 of 3Generalized Successional PatternMechanisms of SuccessionTwo major types of forcesAllogenic-geologic/climatic forces change the environment which causes a bioticshift. e.g.Autogenic-modify environment to make it less favorable to selfProcessesa. b. c. Autogenic forcesColonization—invasion and survivalrate depends on:Pioneer species—different strategies for primary and secondary successionModification of physical characteristics—many species modify the site to make itless favorable to themselves. E.g.Displacement of speciesInteractions between plant speciesa. Facilitationb. ToleranceFTTS F04 Paul’s Lecture 11/8/04 Page 3 of 3c. Competition/inhibition i. Competition ii. Inhibit seed dispersal/establishment iii. Alteration of soil organic chemistry1. Allelopathic chemicalsLegaciesGuildsSpecies within a given community form guilds based on common interests in mycorrhizalfungi and perhaps other beneficial soil organismsEarly colonizers in secondary succession facilitate colonization by members of sameguild and inhibit colonization by members of other guilds. May also include animals thatare dependent on the mycorrhizal fungi for food, e.g. voles, flying squirrels, northernspotted owl.Succession workshop (30 minutes total)Form groups of three students.There is currently a big pile of glacial till soil that was excavated for the Seminar IIbuilding foundation over near the Child Care Center. One possible fate of this soil is tospread it out over the field to form a layer about 2 feet thick. Your work is to designate asuccessional plant sequence for this soil that ultimately results in a forest. List the plantsyou would use and what they would contribute to the ecosystem. Pay close attention tothe cycling of nutrients in the cycle and note how these would
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