A wildlife charity is monitoring two woodland habitats: Habitat A, which has been managed to support a wide variety of plant, insect, bird and mammal species, and Habitat B, a monoculture plantation containing only one species of conifer tree. Explain why Habitat A is likely to be more stable than Habitat B, and outline two ways in which human activities could reduce the biodiversity of Habitat A in the future.

Pearson Edexcel A-Level Biology A (9BI0) — 2.5 Biodiversity · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Habitat A is a managed broadleaf woodland containing hundreds of different species. Habitat B is a commercial conifer plantation containing a single tree species. Both habitats cover the same area of land.

Model answer (5 marks)

Habitat A has a higher level of biodiversity than Habitat B, meaning it contains a greater variety of species and a larger number of different species.

Because of this diversity, if one species in Habitat A is lost or its numbers fall, other species can fulfil similar ecological roles; food chains remain intact and the ecosystem stays stable.

In contrast, Habitat B is a monoculture of a single conifer species. If that species is affected by disease, pest or other disturbance, the whole habitat is destroyed and all species that depend on it are lost.

Human activities that could reduce the biodiversity of Habitat A include deforestation or land clearance for agriculture or housing, which removes habitat and species.

A second distinct human activity that could reduce biodiversity is the introduction of invasive species or the use of pesticides/herbicides, which kill non‑target species and alter community structure.

Examiner tips

  • Use the word ‘biodiversity’ and explain the link between species richness and stability. Show the two contrasting scenarios (loss of one species vs loss of all species). Give two different human activities, each with a brief explanation of the impact.

Common mistakes

  • Confusing ‘species richness’ with ‘species diversity’ without linking to stability. Listing the same activity twice or giving a non‑distinct activity such as ‘climate change’ without specifying its effect on biodiversity.

Mark scheme (5 marks)

  1. Habitat A has greater biodiversity than Habitat B, meaning it contains a greater variety of species / a greater number of different species
  2. In Habitat A, if one species is lost / decreases in number, other species can fulfil similar roles / food chains are not broken, so the ecosystem remains stable
  3. In Habitat B, loss of the single tree species / a disease or pest affecting the one species would destroy the entire habitat / all dependent species would be lost
  4. One valid human activity that could reduce biodiversity of Habitat A, e.g. deforestation / land clearance for agriculture or housing / pollution of soil or waterways / introduction of invasive species / use of pesticides / herbicides killing non-target species
  5. A second distinct valid human activity that could reduce biodiversity of Habitat A (different from point 4)

Key terms in this question

biodiversity · species · monoculture

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