BiodiversitySpec 4.7.3.1
- Biodiversity
- The variety of all the different species of organisms on Earth, or within an ecosystem.
A great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.
The future of the human species on Earth relies on us maintaining a good level of biodiversity. Many human activities are reducing biodiversity, and only recently have measures been taken to try to stop this reduction.
The next sections explain how waste, land use, deforestation and global warming each have an impact on biodiversity.
Waste managementSpec 4.7.3.2
Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced. Unless waste and chemical materials are properly handled, more pollution will be caused.
| Where | Causes |
|---|---|
| In water | Sewage, fertiliser or toxic chemicals |
| In air | Smoke and acidic gases |
| On land | Landfill and toxic chemicals |
Pollution kills plants and animals, which can reduce biodiversity.
Land useSpec 4.7.3.3
Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste.
Peat bogs
The destruction of peat bogs and other areas of peat to produce garden compost reduces the area of this habitat. This reduces the variety of different plant, animal and microorganism species that live there (biodiversity).
The decay or burning of the peat releases carbon dioxide into the atmosphere, which contributes to global warming.
There is a conflict. People want cheap, available compost to increase food production, but peat bogs and peatlands need to be conserved as habitats for biodiversity and to reduce carbon dioxide emissions.
DeforestationSpec 4.7.3.4
Large-scale deforestation in tropical areas has occurred to:
- provide land for cattle and rice fields
- grow crops for biofuels.
| Implication | Why |
|---|---|
| Loss of biodiversity | The habitat is destroyed, so many species lose their food and shelter and die out |
| More carbon dioxide in the atmosphere | Fewer trees means less photosynthesis, so less carbon dioxide is removed. Decay and burning of the trees release carbon dioxide |
| Contribution to global warming | Higher carbon dioxide levels contribute to global warming |
Cleared land can provide food and fuel crops, so there is a conflict between the economic needs of people and protecting the environment.
Global warmingSpec 4.7.3.5
Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to 'global warming'.
Some biological consequences
- Loss of habitats, for example as ice melts or as sea levels rise and flood low-lying areas.
- Changes in the distribution of species, as organisms move to cooler areas or cannot survive where they were.
- Changes in the migration patterns of animals.
- Some species may not be able to adapt or move, and may die out, which reduces biodiversity.
The evidence
The scientific consensus about global warming and climate change is based on systematic reviews of thousands of peer reviewed publications.
In a complex context the evidence can be uncertain or incomplete. The climate depends on many factors, and predictions use models, so scientists may not agree on exactly how much the temperature will change.
Maintaining biodiversitySpec 4.7.3.6
Human interactions in an ecosystem can be negative or positive. You need to describe both and explain their impact on biodiversity.
| Negative interactions | Positive interactions |
|---|---|
| Building, quarrying, farming and dumping waste reduce the land available | Breeding programmes for endangered species |
| Pollution of water, air and land | Protection and regeneration of rare habitats |
| Destroying peat bogs and clearing forest | Reintroduction of field margins and hedgerows in agricultural areas where farmers grow only one type of crop |
| Releasing more carbon dioxide and methane | Reduction of deforestation and carbon dioxide emissions by some governments |
| Dumping waste in landfill | Recycling resources rather than dumping waste in landfill |
Scientists and concerned citizens have put in place programmes to reduce the negative effects of humans on ecosystems and biodiversity.
| Programme | How it helps biodiversity |
|---|---|
| Breeding programmes for endangered species | Increase the numbers of a species so it does not die out |
| Protection and regeneration of rare habitats | Keeps the habitat and the species that depend on it |
| Reintroducing field margins and hedgerows | Gives shelter and food for wildlife in fields where only one crop grows, so more species can live there |
| Reducing deforestation and carbon dioxide emissions | Protects forest habitats and slows global warming |
| Recycling instead of landfill | Uses less land for dumping waste and reduces pollution |
Conflicting pressures
Maintaining biodiversity is not always easy. There are conflicting pressures. Farmers want land for crops and animals, people need food, fuel and homes, and conservation costs money. Reducing emissions or protecting habitats may reduce profits or jobs.
Quick check
Define biodiversity.
Show answer
The variety of all the different species of organisms on Earth, or within an ecosystem.
Name three ways humans reduce the land available for other organisms.
Show answer
Any three of: building, quarrying, farming, dumping waste.
Why does destroying peat bogs add to global warming?
Show answer
The decay or burning of peat releases carbon dioxide into the atmosphere.
Which two gases are increasing in the atmosphere and contributing to global warming?
Show answer
Carbon dioxide and methane.
Give two programmes that help maintain biodiversity.
Show answer
Any two of: breeding programmes, protecting rare habitats, hedgerows and field margins, reducing deforestation and emissions, recycling.