Fragile Environments Flashcards
What are fragile environments
Natural environments that are sensitive to and are easily abused by human activity
How to measure environmental fragility
- closely related to the pressure we put on them
- ecological footprint is a measure of the mark that humans make on the natural world
- the ecological footprint of a country shows us where we can expect environments to be made fragile
Characteristics of desertification
- absence of surface water and dried up water courses and ponds
- lowering of water table
- vegetation become degraded and lost
- increased soil erosion as bare soil is exposed
Characteristics of deforestation depend on
Type of felling
- clear felling- forest is completely cut down
- selective felling- only best trees have been extracted
How long the deforestation took place
- freshly sown trunks and burnt saplings vs large fields surrounded by a fringe of trees
Where does deforestation usually take place
Most severe in the deciduous forests of the warm temperate parts of Europe, China and the USA
Where does desertification usually take place
In semi arid places and on the edges of existing hot deserts
How does desertification take place
- starts with a usually semi arid area
- some natural change or human activity leads to vegetation being degraded
- the lack of vegetation leads to reduced transpiration and bare soil being exposed - soil erosion
- over time the land becomes drier and the soil becomes less fertile - desert like landscape
Causes of desertification- droughts
- rain is less predictable and there are droughts
- vegetation dies
- the lack of vegetation leads to reduced transpiration and bare soil exposed
- increases soil erosion
- land becomes drier and soil quality decreases
Causes of desertification- changing intensity of rainfall
- intense rain
- soil cant absorb the water as it is too saturated
- depletes the local water sources
- vegetation dies
- the lack of vegetation leads to reduced transpiration and bare soil being exposed - soil erosion
- over time the land becomes drier and the soil becomes less fertile - desert like landscape
Causes of desertification - population growth and pressure
- rapid population growth put more pressure on the land to grow more food
- can lead to overgrazing
- too many cattle/goats can destroy the vegetation by trampling and eating it
eg. waterholes in Sahel
Factors affecting ecological footprint
- rate of population growth
- level of consumption of resources per person
- type of technology
Causes of desertification - migration
- as desertification takes hold in one area, people may migrate elsewhere in search of food and water
- this leads to population growth in another area
- again leading to overgrazing
Countries in the Sahel
Chad, Nigeria and Ethiopia
Causes of deforestation - commercial timber extraction
(globally 26 percent)
- selective logging (only valuable trees) - timber extraction
- as they fall they damage other trees
- even more damage in clear feeling for pulp
Causes of deforestation - agriculture
- areas of rainforest cleared for plantations
- grow single crops like rubber or coffee
- grassland is grown which huge herds of cattle graze on before another area is cleared
Causes of deforestation - hydroelectric power
- rivers are dammed
- huge areas of forest are flooded as a result
Causes of deforestation - transport (road building)
- roads have been built to enable minerals, timber, cattle and crops to be moved easily
- roads also bring in new settlers who clear areas to farm
Causes of deforestation - mining
- large areas of forest are cleared for the open cast minerals
eg. iron, gold, copper
Causes of climate change - Milankovitch cycles
Variations in the earths orbit around the sun
These affect the amount of sunlight the earth is receiving and therefore its climate
Causes of climate change - volcanic activity
Ash ejected into the earths atmosphere blocks solar Radiation (sunlight)leading to a decreased temperature