SEE-U 2000: Black Rock Forest - Lecture

## Lecture Archive

## 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
  - number of species
- 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