4 Deforestation and peat destruction

p.270

Objectives

• Students should learn:• that large-scale deforestation affects

atmospheric carbon dioxide directly and methane levels indirectly

• that loss of forest leads to reduction in biodiversity

• that the destruction of peat bogs and other areas of peat releases carbon dioxide into the atmosphere.

Outcomes

• Most students should be able to:• define deforestation• describe the ways in which deforestation affects carbon

dioxide and methane levels in the atmosphere• describe the impact of deforestation on biodiversity• explain why the use of peat-free compost should be

encouraged.• Some students should also be able to:• explain in detail the effects and consequences of

deforestation.

Specification

a) Large-scale deforestation in tropical areas, for timber and to provide land for agriculture, has:

■ increased the release of carbon dioxide into the atmosphere (because of burning and the activities of microorganisms)

■ reduced the rate at which carbon dioxide is removed from the atmosphere and ‘locked up’ for many years as wood.b) Deforestation leads to reduction in biodiversity.c) Deforestation has occurred so that there can be increases in cattle and in rice fields to provide more food. These organisms produce methane and this has led to increases in methane in the atmosphere.d) The destruction of peat bogs and other areas of peat releases carbon dioxide into the atmosphere.

Biology B3 4.4 Deforestation and peat destruction

Answers to in-text questions

a Deforestation is the cutting down of large areas of forest and burningor removing the trees. There is no replacement planting. b Rice growing in paddy fields and cattle reared to produce cheap beef.Summary answers

1 Deforestation: the cutting down of large areas of forest. Slash-and-burn: cutting down trees and then burning the whole area. Biodiversity: the range of different species or and the number of oganisms in a area. Peat: substance made when plants decompose slowly and incompletely in an acidic, low oxygen environment. 2 Carbon dioxide produced by burning of trees; carbon dioxide produced by decomposition; less carbon dioxide removed from atmosphere by growing plants. 3 a i Rice fields are increasing because there is a population explosion; rice is the staple diet for many people, so more rice is needed. Cattle are increasing because there is a demand for cheap beef to supply burgers. Increased standards of living also means a greater demand for animal products generally. ii Peat bogs decreasing as peat is used as a fuel and for compost for gardeners.

b Rice and cows lead to increased levels of methane in the atmosphere. Methane is a greenhouse gas. Loss of peat bog leads to increase in carbon dioxide levels as peat is burnt or used as compost.

 

Compulsory slides you must complete and use;

large-scale deforestation affects atmospheric carbon dioxide directly

• Describe how• http://

rainforests.mongabay.com/deforestation_alpha.html for deforestation rates in different countries

• Could use http://www.worldlandtrust.org/ to help

Biodiversity

• Get the class to write down what this is

large-scale deforestation affects methane levels indirectly

• P.271 give detail

loss of forest leads to reduction in biodiversity

• P.271

destruction of peat bogs and other areas of peat releases carbon dioxide into the atmosphere

• P.271

‘fun’ activity

• Find, show and tell some pictures of ‘bog bodies’

• Get the class to answer why they think they did not decompose

Other slides you may use to help you

Forests cover 10% of the Earth but are home to 50% of all animal and microbial species, and 70% of higher plants.

An important habitat

As the human population increases, more forests are being destroyed to make room for houses, factories and farmland. This is called deforestation.

What effect is this having on the environment and the wildlife that forest habitats support?

Deforestation destroys habitats, but wood can still be harvested in a sustainable way by:What is sustainable forestry?

replanting – new trees are planted to replace those that are cut down.

coppicing – harvesting the stems of young trees and allowing them to regrow.

However, developing countries may not have enough money to invest in sustainable forestry. How could these countries be helped?