
Lecture Archive
Community Ecology: An Introduction to the Players and How to Measure Communities
Community Ecology: An Introduction to the Players and How to Measure Communities
Columbia University
Atlantic Forest, Brazil
Community Ecology
- Next step up the ecological hierarchy from populations
- Definition: A population of species co-occurring populations
- Together, they comprise the biotic component of the ecosystem
Community Function
- More than a Collective properties of participant species
- Emergent properties
- ecosystem stability
- limits to similarity of competing species
Community Drama Players
- Producers (Module 6)
- Primarily plants and bacteria
- Consumers (Module 7)
- Herbivores, Predators, Parasites, Parasitoids, Mutualists
- Decomposers (Module 8)
- Vertebrates, Invertebrates, Fungi, Bacteria
Community Features
- Richness
- Abundance
- Diversity
- Evenness
- Community Similarity
- Trophic Levels
- Feeding Guilds
- Endemism
- Vertical Structure
Community Features
- Richness
- Abundance
- number of individuals
- either per species or gross abundance
Richness and Abundance
- Most commonly used features of community for summarizing
- Most intuitive
BUT
- Could provide misleading results
- Why?
Problems w/ Richness & Abundance
- Edge species are often invasive/exotic, anthropophilic, and are everywhere
- May lead people to conserve areas that are less important
- Do not take into account endemicity
Other Community Features
- Trophic Levels
- Feeding Guilds
- Evenness of species
- Community Similarities
- Vertical & Horizontal Structuring
- Diversity (next most commonly used)
Diversity Indices
- Definition
- Combination of richness & abundance, combine these data in different fashions
- Information Theory based (assessing certainty of sampling all species present)
- Sensitivities
- Unevenness in abundance often leads to strange results (e.g., deer herbivory study)
- Unequal collecting effort
Diversity Indices
- Methodology
- enter data, calculate indices
- general comparison of relative sizes
- some advocate for parametric statistics
- Common Indices
- Shannon-Wiener
- Simpson
- Brilluoin
- Fisher's alpha
Today's Activity - Brazil
- What is the influence of plant biodiversity in home gardens on that of beneficial and harmful insects?
- Could advocate for intercropping, a more sustainable form of farming
Methods
- Sample insects using pan traps (water, salt, soap)
- Use three home gardens of different overall plant biodiversity
Methods II
- Remove insects from pan traps
- Isolate parasitoids
- Isolate homopterans
- Sort both to morphospecies
- Total richness and abundance
- Input into computer program
- Calculate diversity indices
Methods III
- Compare plots to each other
- Make bar graphs of values and indices
- Use photos: sites, process, and animals
- Write up a paper of the class
- Use PowerPoint
- IN ONE HOUR
- Football at 5:30