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Unlock This CourseHumans affect every ecosystem they touch. Some of these interactions are negative, because they lower biodiversity. Others are positive, because they protect or increase it.
Taking land for building and farming, cutting down forests, producing waste and pollution, and adding carbon dioxide to the air. These shrink habitats and make it harder for species to survive. They were covered in the two lessons before this one.
Programmes that protect species and habitats, and that cut down the harm humans do. Scientists and concerned citizens have put these programmes in place, and this lesson looks at five of them.
The programmes below all have the same aim: to reduce the negative effects of humans on ecosystems and so to protect biodiversity.
An endangered species is one that is at risk of dying out completely. If too few of them are left, the species could become extinct.
Key terms:
In a breeding programme, the animals or plants are kept somewhere safe, such as a zoo or a nursery, and are helped to reproduce. The young that survive can then be used to build up the population. This stops the species dying out and keeps it as part of the ecosystem, which protects biodiversity.
Many species can only live in one type of habitat. If the habitat disappears, so do they. Two things help here:
Protecting a habitat protects every species living in it at the same time, which is why this is such an effective way to keep biodiversity high.
In some farming areas, farmers grow only one type of crop over huge fields. Hedgerows and field margins were removed to make the fields larger. This leaves very little living space for wild species.
A hedgerow is a line of shrubs and small trees between fields. It gives shelter, food and nesting places for birds, insects and small mammals.
A field margin is a strip of uncultivated land left around the edge of a field. Wild flowers and grasses grow there and support insects and other animals.
Reintroducing field margins and hedgerows gives species a habitat again in farmland, so the number of different species in the area goes up.
Some governments have taken action on a large scale.
Only governments can make laws and agreements that cover a whole country, which is why their action matters so much.
Waste that is dumped in landfill takes up land and can pollute it. Recycling means turning used materials, such as glass, paper, metal and plastic, back into new products.
Both of these ease the pressure on habitats, so more land is left for wildlife.
Question: A farmer plants a hedgerow along one edge of a field of wheat. Explain how this could increase biodiversity.
Answer: The hedgerow is a new habitat. It provides food, shelter and nesting places, so more species of insects, birds and small mammals can live on the farm. More different species means higher biodiversity.
Protecting biodiversity is not always simple, because different groups want different things. These are called conflicting pressures.
To evaluate a conflict, give the benefits and the costs for each side, then reach a conclusion that you can justify from the information given.
Writing that a programme "saves the environment" is too vague. Always say what changes: the habitat is kept, the population goes up or less land is taken. Another mistake is to mix up protection (keeping a habitat as it is) with regeneration (helping a damaged habitat to recover).
A conservation charity wants to protect a rare species of butterfly that lives only in a small area of wetland. Some local farmers want to drain the wetland to grow crops.
(a) Suggest two ways the charity could help the butterfly. [2 marks]
(b) Give one reason the farmers might disagree with the charity. [1 mark]
(c) Explain how reintroducing hedgerows on farmland could help biodiversity. [2 marks]
(a) Protect the wetland, for example as a nature reserve, so it cannot be drained (1). Run a breeding programme to increase the number of butterflies (1).
(b) The farmers need the land to grow crops and earn money (1).
(c) Hedgerows give a habitat, food and shelter (1), so more species can live on the farm and biodiversity goes up (1).
In part (b), say what the farmers need, such as land, food or income. Do not just say they "do not care" about the butterfly.