Green Roofs and Species Diversity

Green Roofs

• Space for biodiversity

• Eliminate urban heat island effect

• Reflect light from trees and absorb radiation

• Evapotranspiration (sweating)

• Absorb rainwater

• Adds insulation to buildings

Challenges on Green Roofs

• Shallow media depth

• Limited water availability

• Intense sunlight

• Limited space 

Dian Center Green Roof

• Sibyl Levy Golden ‘38 Ecological Learning Center

• Was an ecological learning center

• At first houses many plants separately

• Then native plants took over

Species Diversity

• The number of each species (richness)

• Abundance of individuals per species (evenness) 

Simpsons Index

• Measurement of species dominance from 0-1

• Finds the chance that two individuals randomly selected from an ecosystem are the same species

• low Simpsons index indicated high diversity

Weaknesses of Simpson Index

• Sensitive to changes of abundance in the dominant species

  • So researchers pair it with something sensitive to species richness

• Affected by sample size

Simpsons Reciprocal index

• The reciprocal of the Simpson index

• 0 means a population of 1