Biodiversity keeps ecosystems functioning
Definition
Biodiversity
The number of different species that live in an area.
- High biodiversity gives a food web more feeding links, so the loss of one population is less likely to collapse the whole ecosystem.
- Different species provide pollination, decomposition, nutrient cycling, soil formation, water purification and control of pest populations.
- Genetic variation within wild populations provides alleles that may help species survive disease or environmental change.
- Wild species are possible sources of foods, medicines and genes for breeding disease-resistant or climate-tolerant crops and livestock.
- Habitats and wildlife also support recreation, tourism, scientific study and cultural value.
Example
- If one pollinator population falls, a diverse ecosystem may contain other pollinator species that continue fertilising flowering plants.
- Seed and fruit production can continue, which supports both plant populations and the animals that feed on them.
Animal conservation prevents extinction
Definition
Conservation
The protection and careful management of species and habitats to maintain biodiversity.
- Protecting and restoring habitats gives animals food, shelter, breeding sites and space to maintain viable populations.
- Legal controls can restrict hunting, collection and trade, while protected areas reduce disturbance and habitat destruction.
- Captive-breeding programmes pair individuals to retain genetic variation, then reintroduce offspring when threats in the wild have been reduced.
- Monitoring population size and genetic diversity shows whether conservation action is working and whether inbreeding is becoming a risk.
- Preventing extinction keeps the conserved species in its food web as a predator, prey, competitor, pollinator or seed disperser.
Example
- A captive-breeding programme increases the number of an endangered predator before animals are released into protected habitat.
- The species is less likely to become extinct, and its prey population remains under predation pressure, helping to preserve the food web.
Reforestation rebuilds habitats
Definition
Reforestation
The replanting of trees in an area where forest has been removed.
- Planting a mixture of native tree species creates varied food sources and habitats for microorganisms, plants and animals.
- As the woodland develops, more niches become available and local species richness can increase.
- Trees remove carbon dioxide from the atmosphere during photosynthesis and store carbon in wood, roots and soil organic matter.
- Photosynthesis releases oxygen, so reforestation can lower atmospheric carbon dioxide and raise oxygen over time.
- Roots bind soil and tree canopies reduce the force of rain, which limits erosion and protects soil habitats and nearby aquatic ecosystems from sediment.
- Connected woodland can form wildlife corridors, allowing animals to move between populations and maintain gene flow.
Common Mistake
- A single-species plantation provides fewer habitats and is more vulnerable to one pest or pathogen than a mixed native woodland.
- Newly planted trees do not replace the biodiversity or carbon store of a mature forest immediately.
Conservation works at two scales
- Local action protects particular habitats and populations, while coordinated action across countries protects migratory species, shared seas and global gene pools.
- Maintaining biodiversity requires continued habitat management because protected populations can decline again if the original pressure returns.
Self review
- Give two biological benefits of high biodiversity.
- How can captive breeding reduce extinction risk?
- How does reforestation change atmospheric carbon dioxide and oxygen?
- Why does mixed native woodland usually support more species than a single-species plantation?
