L5 Tosh - Quantifying and measuring Biodiversity Flashcards Preview

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Flashcards in L5 Tosh - Quantifying and measuring Biodiversity Deck (11)
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1
Q

What 2 major factors control diversity?

A

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

Competition - grazing, plant competition

2
Q

How would adding fertilizer cause a reduction in biodiversity?

A

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

3
Q

What is the Plant Dominance Index?

A

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

4
Q

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

A
  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

5
Q

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

A

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

6
Q

What is the Diversity Index?

A

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

7
Q

What is Shannon’s diversity and evenness?

A

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

8
Q

What is Simpsons Dominance Index?

A

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

9
Q

Give the methods of colonisation on the Hawaiian Islands

A
  • Sea dispersal
  • Wind
  • Animal dispersed plants
10
Q

How do mountains have a varied habitat?

A

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

Alpine flora evolved separately - 91%

11
Q

Why are some animals absent from the Hawaiian Islands?

A

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