Deforestation

Question 1

Nature and spatial distribution of forests

Answer 1

The worlds forested areas total around 40 billion hectares - approximately 31% of the worlds surface

Slightly more than half of forests are found in the tropics whereas the rest are found in temperate regions

Question 2

Define forest

Answer 2

Forests are dynamic biomes that change and adapt over time, and are usually classified by the climate in which they are found

Question 3

Classifications of forests

Answer 3

Primary forest - Virtually untouched containing all natural species
Secondary forest - Partially interfered with containing mostly native species
Plantations - native or non native trees planted for commercial production or for environmental protection

Question 4

Changes over geologic time scales: Last Glacial Maximum - 18,000 - 21,000 years ago

Answer 4

• Less extensive distribution
• Biomes such as grasslands and tundra were more widely distributed
• Forests tended closer to equatorial regions (low latitudes) due to extensive ice sheet cover
• Northern EU had no forests due to ice, Southern EU has mainly grasslands, North America and Japan were dominated by forest, Central Asia was too dry and hot

Question 5

Changes over geologic time scales: Holocene Climatic Optimum - 8000 years ago

Answer 5

• Temperatures and sea levels rose, allowing for the latitudinal expansion of forests
• However, existing forests in coastal regions flooded
• Forest cover expanded such that around 47% of the earths surface was covered

Question 6

What is deforestation?

Answer 6

• The FAO defines it as the long term loss of tree canopy cover to below 10-30%
• Forest degradation occurs when there is loss but it remains above 10-30%
• Afforestation is when forests are formed on land that did not previously have forests

Question 7

Different types of deforestation

Answer 7

• Clearfelling: when select areas are completely removed
• Selection: when certain trees are felled but the understorey remains intact
• Group selection: When a particular group called a coupe is completely removed
• Shelterwood: When only mature trees are felled at intervals
• Seed-tree retention: When trees are cleared however some are left in tact as to not destroy the land

Question 8

Global distribution: Cultivation of land

Answer 8

The agricultural revolution has lead to large scale loss of forest cover from 47% to only 31% of the earths surface
Cultivated land constitutes around one quarter of the earths surface

Question 9

Global distribution: Current trends (poor regions)

Answer 9

• Globally, deforestation peaked in the last two decades of the 20th century as a result of accelerated rates in poorer regions
• For example South East Asia lost more than 30% of its forests during this period

Question 10

Global distribution: Current trends (developed nations)

Answer 10

• Many developed nations have increased their net forest cover through arresting deforestation and/or afforestation
• For example, China have planted approximately 80 million trees in the last 60 years

Question 11

Global distribution: Current trends (quality of cover)

Answer 11

• Globally forest cover quality has declined with 6 million hectares per year of primary forest being downgraded to secondary
• Year on year growth of plantation forest is around 2.8 million hectares