Bio1b Summer 2008 Eric Harris Ecology Lecture 6 Page 1 of 2 ECOLOGY LECTURE 6 COMMUNITY ECOLOGY II STRUCTURE DYNAMICS Reading 7th ed 1165 1175 1185 1194 8th ed 1204 1214 1224 1230 A Community Structure i Richness the number of species evenness the relative abundance of different species ii Techniques for assessing community structure iii Relative Impacts of Different Species within a Community Dominant species Keystone species e g Pisaster Sea otter Ecosystem engineers B Food Webs and Trophic Levels i Types of food web Connectedness Energy flow Functional ii Energy budgets iii Trophic Structure the feeding relationships between organisms iv Gross primary productivity vs net primary productivity Primary and secondary productivity v Ecological efficiency Pyramid of numbers vi Patterns in food webs Length generally short 3 or 4 links from bottom to top Why Inefficient energy transfer limits them Size or design constraints Or why are they so long vii Bottom up vs Top down controls viii Use of food webs Predicting pollutant movement and concentration Predicting community effects of introductions or extinctions Designing artificial communities Updated on 06 30 08 Bio1b Summer 2008 Eric Harris Ecology Lecture 6 Page 2 of 2 C Succession i Types of succession Primary succession vs secondary succession Degradative succession Use of succession in forensic science ii Mechanisms of succession Facilitation Tolerance Inhibition iii The influence of animals iv The climax community v Intermediate disturbance hypothesis vi Practical applications Management of nature reserves recovery from disturbance e g fire reclamation of land Updated on 06 30 08
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