Communities vary in the number of species they contain. Knowledge of this number is important to understand the structure of the community. The number of species in a community is referred to as species The relative abundance of species is also important. For example, two richness. communities may both contain the same number of species but one community may be dominated by one species while the other community may contain large numbers of all species. The relative abundance of species is called Communities dominated by one or a few evenness. species have a low evenness while those that have a more even distribution of species have a high evenness. Species includes both species richness and evenness. diversity Describe how species and are different. richness evenness Describe the species and for each stream. richness evenness Identify which stream you expect to be the most diverse and defend your choice. Next you will learn how to measure the macroinvertebrate diversity for each stream using Shannon’s Diversity Index. It is calculated using this equation: H’ = pi (ln(pi)) where = the proportion of individuals of species pi i – ∑ Number of Species ln(pi) pi Individuals Beech 32 Maple 18
Communities vary in the number of species they contain. Knowledge of this number is important to understand the structure of the community. The number of species in a community is referred to as species richness. The relative abundance of species is also important. For example, two communities may both contain the same number of species but one community may be dominated by one species while the other community may contain large numbers of all species. The relative abundance of species is called evenness. Communities dominated by one or a few species have a low evenness while those that have a more even distribution of species have a high evenness. Species diversity includes both species richness and evenness. Describe how species richness and evenness are different. Describe the species richness and evenness for each stream. Identify which stream you expect to be the most diverse and defend your choice. Next you will learn how to measure the macroinvertebrate diversity for each stream using Shannon’s Diversity Index. It is calculated using this equation: H’ = – ∑ pi (ln(pi)) where pi = the proportion of individuals of species i Species Number of Individuals pi ln(pi) Beech 32 Maple 18
Insects%20as%20Bioindicators%20of%20Stream%20Health.docx