Ecosystem Types and Diversity (L5 - Guest Lecture)

Question 1

Why is biological diversity important

Answer 1

• associated with increased productivity and resilience of ecosystems
• forms basis of economic products (food,, fiber, medicines etc)
• “species rights”, “ecosystem rights”
• extinction :(
• is measured by number of types of organisms and the equitability in distribution

Question 2

How do trees help biodiversity

Answer 2

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

Question 3

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

Answer 3

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 4

Some species enhance biodiversity. What are they and how do they do so

Answer 4

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

Indicator - serves as measure of environmental conditions (eg, mayflies used as indicator of stream water quality)

Foundation - directly provide habitat for other species (eg trees in a forest)

Umbrella - if protected, will protect other species (this species shares a lot of needs as other species, therefore protecting their needs will protect other species)

Flagship species - used in conservation as ambassador, large and charismatic for advertising purposes (eg, falcon, tiger, gorilla, elephant etc)