SEE-U 2000: Atlantic Forest - Module 5:Exercise 5

## Exercise 5: Similarity of Home Gardens
Module 5: Community Ecology: An Introduction to the Players and How to Measure Communities

### Your Questions

1. How similar are home garden communities?

### Background

A community is composed of a group of species, in the same taxa, that is found in the same area. Communities have certain characteristics, such as structure (vertical, horizontal and species composition), species diversity (richness and relative abundance) and trophic interactions (food chains and food webs) that can be used to distinguish different types.

One of the important aspects of community ecology is the comparison of two or more communities. This type of comparison is done by calculating a coefficient of similarity or beta diversity value and can be done either qualitatively or quantitatively. The values for similarity range from 0%, when no species are common to 100% when both communities have exactly the same compositon, in my ecological studies a value of greater than 50% indicates a high similarity between communities. When more than two communities are compared, another type of analysis, multivariate, is used. There are two main types of multivariate analysis. One is classification, in which groups are formed based on the presence or absence of certain species. The other is ordination in which groups are formed based on a mathematical algorithm. In both types, the results need to be interpreted, using ecological knowledge of where the samples were collected.

An aspect of development, especially in regard to agricultural practices, is the transformation of natural communities into artificial ones, with a substantial loss of species diversity. When done on a large scale, a monoculture might be the result. On a smaller scale, such as in a home garden, it is possible to encounter a slightly higher level of diversity.

In this exercise, the objective is to compare the diversity of home gardens. This will involve collection of data on what kinds of plants are used in these gardens. Different gardens will be compared to determine if there is a high or low degree of similarity between different families and also a multivariate analysis, using classification techniques will be done to determine if it is possible to form groups.

### Your Assignment

1. Compare beta diversity among home gardens and run a cluster analysis

### Methodology

1. Task A—Selection of sampling sites
   - Choose sampling sites
2. Task B—Data collection
   - Establish sampling sites
   - Collect data
3. Task C—Data analysis and write up
   - Data entry into computer
   - Estimate local diversity in each community type
   - Compare beta diversity among community types
   - Run a simple classification (Cluster analysis)
   - Summarize results for presentation (written and oral)

### Objectives

1. Introduce concepts of beta diversity
2. Introduce concepts and methods of multivariate analysis

### Key Skills

1. Collection techniques for community level data
2. Learn methods for comparing communities
3. Familiarity with different techniques of multivariate analysis

### Timetable

Total time—1 day

1. Morning
   - Locate the sampling sites
   - Establish sampling units
   - Collect data on number and type of species present
2. Afternoon
   - Terminate data collection, if necessary
   - Data entry and analysis
   - Write up report

### Materials Needed

1. Field notebook and writing equipment
2. Material for marking quadrats — stakes, string, hammer
3. Tape measures (50 m)
4. Compass and GPS
5. Programs for similarity analysis (from Brower, Zar & von Ende)
6. Program for multivariate analysis (PC—ORD ver. 4.0)