L5 Tosh - Quantifying and measuring Biodiversity

Question 1

What 2 major factors control diversity?

Answer 1

Environmental factors - physical structure, nutrition, resources (competition allows animals to grow at lower nutrient levels)

Competition - grazing, plant competition

Question 2

How would adding fertilizer cause a reduction in biodiversity?

Answer 2

Adding fertilizer increases resources, this encourages dominant species to out compete smaller species, ending with a reduction in biodiversity

Question 3

What is the Plant Dominance Index?

Answer 3

Aggressive plants need high resources (light, water, nutrients).
Quantifying the competitive ability of the plant species, calculated by 4 categories, scored 1-5 for each. The sum is then divided by 2 to give a score out of 10

Question 4

What are the 4 categories in the PDI? Give an example

Answer 4

1. Growth rate
2. Potential height
3. Potential for lateral spread
4. Litter production

E.g. Stinging nettle scored: 5, 5, 5, 2
DI = 8.5

Question 5

What kind of diversity is usually seen in communities with low dominance scores and why?

Answer 5

Usually, areas with high diversity have low dominance scores. So species with high dominance indexes control diversity, and in turn are controlled by the resources available

Question 6

What is the Diversity Index?

Answer 6

This is the measure of the number of species/families/genera, and the number of individuals of each

Richness: number of species
Evenness: dominance of species

Question 7

What is Shannon’s diversity and evenness?

Answer 7

This is commonly used in ecology, and is the proportion of all individuals that belong to each species. It assumes:

• individuals are randomly distributed and sampled
• that all species in the community are sampled

Natural communities generally fall between H’ = 1.5-3.5

Question 8

What is Simpsons Dominance Index?

Answer 8

This measures the degree of dominance by a few species in the sample.
As D decreases, dominance increases and therefore richness and evenness decrease

Question 9

Give the methods of colonisation on the Hawaiian Islands

Answer 9

• Sea dispersal
• Wind
• Animal dispersed plants

Question 10

How do mountains have a varied habitat?

Answer 10

Alpine environment is split into:
- cool peaks surrounded by lower warm climates

Alpine flora evolved separately - 91%

Question 11

Why are some animals absent from the Hawaiian Islands?

Answer 11

many animal groups are absent - freshwater fish, amphibians and reptiles.

There are only 1 mammal - bats

This is because the ocean is a filter/ barrier