第l4章：群落Chapter14 Community I.Teaching Objective: Know community.community structure,lifestyle Understand biodiversityand L.Focal Points and Difficulties in the Chapter(教学重点和难点) 1.Focus How strong are conections among species? What is the 'nature'of the community?Is it a natural unit of ecological organization? 2.Difficulties Food websand community function What changes with food web complexity? Are communities stable(in equilibrium)or transient(in non-equilibrium)? Historically:emphasis on equilibrium view Current:raises importance of disturbance and non-equilibrium view other prevail? III.Methodology Powerpoint presentation will be the main method.Blackboard will be an assistance.Case studies will be provided. IV Presentation(课堂讲解，学时分配为2学时左右) Warm-up Activity How is community structure quantified and compared? Species richness (S):number of species Biased by rarefaction:individuals/samp Species differ in abundance and thus in role in community.so Species diversity Weights species by their relative abundance Simpson's index:D=1/p Shannon-Wiener index:H=-E p log p Evenness:Ep=D/D where DS En=H/Hag Where=In S