4.6.2 Species Richness

Measuring Species Richness

• Species richness only considers the number of species and does not account for the abundance of individuals within each species.
• It can be determined using random sampling methods:
  1. Divide the area into a grid or use transects.
  2. Use a quadrant or sampling frame to randomly sample different locations.
  3. Record the species found within each sample.

Factors Affecting Species Richness

1. Habitat Size: Larger habitats generally support more species due to increased resources and niches.
2. Environmental Stability: Stable environments can support a wider range of species.
3. Human Activity: Deforestation, pollution, and urbanisation often reduce species richness.
4. Invasive Species: Non-native species can outcompete or displace native species, reducing richness.

Species Richness vs. Species Diversity

• Species richness counts the number of species only.
• Species diversity considers both species richness and the relative abundance of individuals within each species.