Measuring Diversity: Richness, Evenness and Turnover Between Sites · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Beyond counting species

Science · Ecology & Conservation · ages 21-22
Name ______________________   Date ____________

  1. What is species evenness?

    • How the heights of individuals vary among species
    • How evenly individuals are distributed among species
    • How widely the sampling locations are spaced across a site

  2. What is species richness?

    • The number of different species present
    • The total number of individuals present
    • The number of sampling visits to the site

  3. A survey records 12 English oaks, 3 sugar maples, 7 silver birches and 1 American beech. Each name identifies a different species. What is the recorded species richness? Type the number.

    Answer: ______________

  4. Use D = 1 - sum(p²), where p is a species' share of all individuals. A sample has 8 plants of species A and 2 of species B. What is the Gini-Simpson index D?

    • 0.32
    • 0.68
    • 0.80

  5. Two forests each have 8 tree species. One has equal numbers of trees of each species. In the other, 80% of trees belong to one species. Which has greater species diversity?

    • The dominated forest, because abundance determines richness
    • They have equal diversity, because having 8 species fixes their evenness
    • The even forest, because it has less dominance by one species

  6. Two lakes share no species at all. What does that say about turnover?

    • Turnover is low
    • Turnover is high
    • Turnover cannot be judged

  7. Counting species alone is enough, because equal richness always means equal diversity.

    Circle one:   True   False

  8. Two lakes have equal richness, evenness and habitat condition. Each can be protected equally well. One has a threatened species found nowhere else; the other has only widespread species. Which has the stronger claim if the aim is to prevent extinction?

    • Either lake, because equal richness means their species face the same extinction risk
    • The widespread-species lake, because species with large ranges face greater extinction risk
    • The lake with the threatened, restricted species, because its loss could cause extinction
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Beyond counting species W1-mt_d_iIiIArWZ-s1

  1. How evenly individuals are distributed among species · Evenness describes abundances ranging from perfectly balanced to dominated by one species.
  2. The number of different species present · Richness counts species; it does not describe their relative shares.
  3. 4 · The counts describe 23 individual trees belonging to four species. Richness counts species, so the answer is 4, not 23.
  4. 0.32 · The shares are 0.8 and 0.2. Their squares total 0.64 + 0.04 = 0.68. Subtracting from 1 gives D = 0.32.
  5. The even forest, because it has less dominance by one species · Both forests have richness 8. The forest with equal abundances has greater evenness and therefore greater species diversity.
  6. Turnover is high · Zero shared species means complete turnover between the sites.
  7. False · Two sites can each contain three species but have different abundance distributions. Equal richness therefore does not establish equal evenness or equal species diversity.
  8. The lake with the threatened, restricted species, because its loss could cause extinction · The prompt gives a threatened species whose entire range is one lake. With the other stated conditions equal, protecting that lake better addresses the goal of preventing extinction.
Worksheet · LightMySky