L6 Ecosystem Types and Diversity

Question 1

How do trees help biodiversity

Answer 1

Forest with higher tree species diversity show higher productivity and resilience to environmental stress

Question 2

What is the Shannon-Wiener Index and Simpson Index and what are they used for

Answer 2

Shannon - Wiender
H = -∑(from i = 1 to s)pilnpi
s = number of species
pi = proportion of the ith species

Simpson
D = [∑(from i = 1 to s)pi(pi-1)]/S*(S-1)
S = number of species
- D lower = more diverse

These are used to measure species diversity
See TUT 1 and L5 Slides for examples

Question 3

What enhance biodiversity.

Answer 3

Predation - competitive species don’t get the chance to dominate an area, predators eating them gives other organisms a chance

Keystone - enhances by its ecological interaction: predators that keep potentially over dominant species in check etc