Conservation and sustainabilityIB MYP Biology: Revision notes

Conservation means protecting living things and their habitats so that biodiversity is not lost. Humans cause species to become endangered by hunting, destroying habitats, overfishing and pollution. Conservation matters because once a species is extinct it is gone for ever, and every species is part of food webs that other organisms depend on.

Sustainability means using resources at a rate that can be replaced, so that they are still available for future generations.

Protected areas such as national parks and nature reserves are places where hunting, logging and building are banned or controlled. Rangers enforce the rules. Animals and plants can survive and breed in their habitat without human damage.

Replanting (reforestation) means planting new trees to replace those that were cut down. It restores habitats, binds the soil and takes in carbon dioxide. In sustainable forestry, every tree that is harvested is replaced.

Captive breeding is breeding endangered animals in zoos or wildlife centres. The offspring can later be released into protected habitats, as happened with the Arabian oryx. Its limit is that a small starting population has little genetic variation, so inbreeding and genetic disorders are risks.

Seed banks store seeds of many plant species (often at about -18 °C in dry, sealed containers) so that plants can be regrown if wild populations are lost. Cold, dry conditions slow the reactions in the seeds so they stay alive for a long time.

Overfishing happens when fish are caught faster than they can breed, so the population falls and may collapse. Ways to stop it:

• Quotas limit the number or mass of each species that can be caught.
• Minimum mesh sizes let young fish escape so they can grow and breed.
• Banning fishing in breeding areas or in breeding seasons.

Quotas can reduce fishers' income and are hard to police, but without them the stocks could collapse and the industry would end.

Sustainable farming produces food while protecting the environment so that farming can continue in the future. Methods include:

• Crop rotation and leaving some land unused, to keep the soil fertile.
• Using fewer chemical fertilisers and pesticides, and using natural predators instead.
• Keeping hedgerows and strips of wild plants for wildlife.
• Growing trees among crops to protect the soil.

These methods may give a lower yield or cost more, but they protect soil and biodiversity.

In MYP questions you often have to evaluate conservation methods. For each one, give a benefit, a drawback and a conclusion:

• Consider the effect on wildlife, on local people (jobs and income) and on cost.
• Remember that conservation fails if local people cannot earn a living, so solutions that include them are often more successful.
• Finish with a clear decision and a reason, such as 'Plan 2 is best because...'.