Biodiversity within a community：練習題

An ecologist is comparing the biodiversity of two different fields. Field A has a total of 120 individuals across 8 species. Field B has a total of 120 individuals across 8 species. In Field A, the populations are evenly distributed, while in Field B, one species makes up 110 of the individuals.

What can be concluded about the index of diversity (\(d\)) and species richness of these two fields?

An ecologist used random sampling to compare the biodiversity within a community of two different meadows. The following data was collected:

Meadow 1: Total individuals \( (N) = 150 \), \( \sum n(n-1) = 4,200 \)
Meadow 2: Total individuals \( (N) = 150 \), \( \sum n(n-1) = 7,100 \)

Using the formula \( d = \frac{N(N-1)}{\sum n(n-1)} \), what is the calculated index of diversity for Meadow 1 and what does it indicate compared to Meadow 2?

A farmer decides to remove several hedgerows and replace a multi-crop system with a monoculture of wheat. How will these specific changes most likely impact the index of diversity (\(d\)) of the local insect community, and what is the primary ecological reason?

What is the primary definition of species richness within a community?

An ecologist sampled a community and found 4 species with the following number of individuals (\(n\)):
Species A: 20
Species B: 10
Species C: 5
Species D: 5

Calculate the index of diversity (\(d\)) using the formula:
\(d = \frac{N(N-1)}{\sum n(n-1)}\)

A community was found to have 10 individuals of species A, 15 individuals of species B, and 25 individuals of species C. Using the formula \(d = \frac{N(N-1)}{\sum n(n-1)}\), calculate the index of diversity for this community to two decimal places.

Distinguish between the terms species richness and index of diversity, and explain why the index of diversity is considered a more useful measure of biodiversity within a community.

Compare the biodiversity within a community of an ancient woodland to a modern monoculture farm, using the concepts of species richness and index of diversity to justify which would be more stable against environmental change.

An ecologist is investigating the impact of intensive farming on the biodiversity of a local habitat. The following data shows the number of individuals of three different species found in a hedgerow (Habitat A) and a wheat field (Habitat B).

Habitat A: Species 1 (25), Species 2 (20), Species 3 (15)
Habitat B: Species 1 (58), Species 2 (1), Species 3 (1)

a) Calculate the index of diversity \( (d) \) for Habitat B using the formula: \( d = \frac{N(N-1)}{\sum n(n-1)} \). Show your working. (3 points)
b) Both habitats have the same species richness. Explain why the index of diversity is a more useful measure of biodiversity in this comparison. (2 points)
c) Suggest two farming practices that could lead to a decrease in the index of diversity in Habitat B. (2 points)