Biodiversity Measures

1
Biodiversity Measures

• Mean rarity
• Rarity can be by area or by ecosystem
• Would populations with low rarity or high rarity
  be more diverse?

2
Mean geographic rarity of five plant families in
Central and South America
3
Diversity

• Sample A 10 species in a square meter
• Sample B 5 species in a square meter
• Sample A is more diverse right?
• But what about the distribution?

4
Sample A
Sample B
5
Shannon-Weaver Index

• If a species makes up a fraction p of the
  population, you can calculate
• -p x log(p)
• Add that up for all species, and you have the
  index.
• Takes the proportions into account.