StemUp: OCR A A level Biology 6.3.2 Populations and sustainability

What is succession? (1)

The variety of processes that occur over time in species that occupy a certain area

What is primary succession? (1)

The progressive colonization of bare rock or barren terrain by living organisms

What is a pioneer species' role in succession? (3)

- Colonises a barren area first

- Changing the abiotic factor

- To make the environment less hostile for other species

How do species change the environment during succession? (2)

- To become more suitable for others with different adaptations but less suitable for the previous species

- Thereby changing biodiversity

What is a climax community in succession? (2)

- When a stable state is reached

- With high biodiversity and the presence of new species

What is secondary succession? (1)

The recolonisation of an area after a previous community has been removed or destroyed

What is conservation? (3)

- The maintenance of biodiversity

- Including diversity between species, genetic diversity within species

- And the maintenance of a variety of habitats and ecosystems

What is preservation in the context of conservation? (2)

- The maintenance of habitats and ecosystems in their present condition

- Minimising human impact

Why is a balance between conservation and human needs necessary? (3)

- Necessary to sustain natural resources

- Given the increasing demand for raw materials and food

- Due to human population growth

What is coppicing in timber management? (1)

The practice of cutting tree stems close to the ground to promote regrowth

What is pollarding in timber management? (2)

- Cutting the tree stem higher from the ground

- To prevent animals from eating the shoots

What is rotational coppicing? (2)

- The process of coppicing different areas in sequence

- To allow time for regrowth

How can fish stocks be managed? (2)

- By preventing overfishing

- Using aquaculture

What is in situ conservation? (3)

- Involves conserving species within their natural habitat

- Maintaining biodiversity

- Includes creating legislations, wildlife reserves, and reintroduction programs

What are the advantages of in situ conservation? (4)

- Conserves species without removing them from their habitat

- Ecosystem integrity is also maintained as the species are able to play a vital role in the functioning of the ecosystem

- Cheaper than ex situ conservation

- ​Protects the biodiversity and the crucial elements of the ecosystem

What are the disadvantages of in situ conservation? (4)

- The habitat may be too fragmented to ensure a sustainable population

- Too much genetic diversity may have already been lost to allow the species to adapt to change in their natural environment

- Wildlife reserves may be damaged by ecotourism

- The conditions that caused the area to have a loss of species may still be present

What is ex situ conservation? (2)

- Involves conserving species outside their natural habitat

- Such as in zoos, botanical gardens, and seed banks

What are the advantages of ex situ conservation? (3)

- Protects organisms from predation and poaching

- Help attract funding and awareness

- Techniques such as artificial insemination are used to maximise reproductive success and genetic diversity

What are the disadvantages of ex situ conservation? (3)

- Limited genetic diversity

- ​It may be difficult to provide a suitable environment

- ​Many animals may also be unable to be re-introduced into the wild as they will not have learnt the necessary behaviour