Causes of Reduction of Biodiversity

Increase in human population causes the following problems:

• Land used for more buildings, growing crops, landfill sites, roads and rearing animals. As a result, habitats and food webs are being disruptted leading to a reduction in biodiversity.
• Improper dumping of waste
• Raw materials are being used up quickly.
• Over fishing is resulting in fish stock being reduced.
• Increasing amounts of industries and domestic waste are being produced. This results in more land fill sites being needed resulting in large areas of landbeing unsuitable for plant and animal life.

Water Pollution - Water can be polluted in many different ways eg, with toxic chemicals from factories, raw sewage and fertilisers.

Sewage and fertilisers can be responsible for increasing the amount of mineral ions in rivers, lakes etc, et nitrates,

Nitrates are needed byplants to make proteins for growth. As a result of incresing nitrate levels in the water, the following can occur:

• Algae in theh water reproduce rapidly so they use the extra nitrates to make proteins for growth.
• The algae form a layer over the surface of the water (algae bloom) which prevents light from entering.
• Plants, living under the water surface, die due to the lack of light for photosynthesis.
• Bacteria in the water decomposes the dead plants. As a result of them having food, they increase in number.
• The extra bacteria use up more oxygen from the water for respiration.
• The oxygen level in the water decreases resulting in the death of animals such as fish and insects as they have insufficient oxygen for respiration.

Air Pollution - Air can be polluted with smoke and gases such as nitrogen oxides and sulfur dioxide, which are both produced by burning fuels.

Acid Rain - Sulfur dioxide goes into the air and idssolves in water vapours to form dillute sulfuric acid, which makes the rain acidic which gts into ponds and lakes causing deaths of plants and animals. It washes the essential minerals ions out of soil, causing plantss to dieas they can't absorb the essential mineral ions needed for healthy growth.

Controlling Acid Rain:

• Cars are fitted with catalytic convertors which remove gases like sulfur dioxide before they are released into the air.
• Systems have been put into the chimney of power stations and factories which "clean" the gases before they enter the air.
• In power stations cleaner low sulfur fuels are being used to generate eletricity.

As a result over the last 40 years the sulfur dioxide in the air has decreased.

Indication Of Pollution:

• The presence or absence of certain invertebrate animals can indicate the amount of water pollution - bloodworms are usually found in polluted water whereas mayfly nymphs are found in unpolluted water.
• Lichens can be used to indicated the level of air pollution.

Land Pollution - Land polluted by toxic chemicals, pesticides, used when growing crops. Pesticides destroy other living organisms which prevent the crops from growing.

Types Of Pestcides:

• Inscecticides - kill inscets
• Fungicides - Kill fungi
• Herbicides - Kill weeds

Pollution Kills animals and plants, which can reduce biodiversity.

Deforestation - this involves the large scale of cutting down trees for the following reasons:

• To provide wood for manufacturing purposes.
• Provide land for buildings, rearing animals or growing crops.
• To provide wood for fuel.
• Building roads.

Consequences Of Deforestation:

• Habitats are destroyed and food sources of some animals, effecting food webs so biodiversity is reduced.
• Less carbon dioxide is being removed from the air for photosynthesis. As it is a greenhouse gas it contributes to global warming.
• As some treesare burnt this also replaces carbon dioxide into the air.
• If the trees are left to decay, decomposition is brought about by bacteris. Carbon dioxide increases when bacteria respire.

Sustainable Development - Improving the quality of life without comprising future generations. Careful planning is needed at local, regional and global levels in order to manage sustainability.