Lesson 22- What is the global distribution of wildfires and why is this the case?

Question 1

Why is climate a reason for the distribution of wildfires?

Answer 1

• El Nino means that less evaporation occurs in North and South America therefore more wildfires
• La Nina means that more evaporation occurs in North and South America therefore less wildfires here

Question 2

Why is weather a reason for the distribution of wildfires?

Answer 2

• Local wind patterns for example the Santa Ana winds can aid fire spread
  -Creates ideal conditions for wildfires to form
• The Sanat Ana winds are winds that blow south from a high pressure system that normally sits over Nevada
• Change in topography towards the coastline
  -Pushes dry air towards cities like LA increasing wildfire risk

Question 3

Why is a fuel characteristics a reason for the distribution of wildfires?

Answer 3

• Size, shape, moisture (more moisture descreases risk), arrangemnent (more dense)

Question 4

Why is the vegetation type a reason for the distribution of wildfires?

Answer 4

• Chaparrall-Shrubland-less fire as they are more spread out
• Boreal forest-crown fires
• Savannah-Grassland-Surface fires
• Peatlands-moorlands-ground fires

Question 5

Why is urbanisation a reason for the distribution of wildfires?

Answer 5

• Urbanisation brings more people within a closer proximity to wildland
• Construction can start fires
• Can acctually change the climate

Question 6

Why is Forest Clearence a reason for the distribution of wildfires?

Answer 6

Reduced vegetation cover, fewer trees, shrubs and other plants that wouldotherwise act as a barrier against wildfires

Question 7

Why do we need wildfires?

Answer 7

• The natural fire cycle
• Aids growth of ecosystems as they kill insects and diseases that harm trees
• By clearing the underbush, fires can make way for new grasses, herbs and shrubs that provide food and habitats for crimals and birds
• If they are low intensity, they can clean up debris, add nutrients to soil and open up space to let sunlight on the ground

Question 8

Role and propcesses of fire within an ecosystem?

Answer 8

• Natural forst fires are usuallly started by lightening strikes and once ignited their spread is dependant on weather patterns
• Once the fire has burned itself out succession begins, can take 300 years
• The third stage is characterised by the absence of larger trees and denser ground vegetation due to the increased light
• The trees get bigger and competition for light and other resouces tends to thin out. Means fires are uncommon as there is reduced vegetation on the ground so its more difficult to ignite the tree tops
• Forest canopy becomes uneven and pines die. This final succession persists until a fire brings it back to the first stage

Question 9

What are the patterns in global distribution of wildfires?

Answer 9

• Majority of wildfires occur within the Northern Hemisphere
• More specifically, a great proportion occur within North america as they are more susceptible to droughts which mean that vegetation has less moisture

Question 10

How do fires create wind?

Answer 10

• The hot air generated will rise and create an updraft

Question 11

Why do fires move uphill more quickly?

Answer 11

• They move faster uphill as they need fuel, oxygen and also heat rises so therefore the speed it spreads at is further accelerated by this force

Question 12

Why do fires spread so quickly?

Answer 12

• The heat from the fire drys surrounding fuel sources and therefore makes them more flammable

Question 13

Why would fires spread fastest on a south facing slope?

Answer 13

• South facing slopes have more sunlight energy

Question 14

North American fires

Answer 14

• Usually caused by lightning except for Mexico where 97% are for agriculture
• Climate means that fires can start at any time during the year
• US fire season starts early spring through to October and peaks in July, August and September

Question 15

Impacts of fires in North America

Answer 15

• Social- Wildfires contribute to 25-50% of PM 2.5 exposure in the US, kills 500 elderly in the US per year
• Environmental- in 2020 Californias Castle Fire destroyed 10% of the worlds mature giant sequoias

Question 16

South American Fires

Answer 16

• Studies have shown that 50-90% of uncontrolled fires began as agricultural that then grew out of control
• However, the vast majority of forest fires in Brazil are began intentionally

Question 17

Impacts of fires in South America

Answer 17

• A prolonged megadrought has affected Chile since 2010, leading to decreased cloud cover and glacier shrinkage in the Chilean Andes.
• Threatening the biodiversity of the Amazon and indigenous tribes that live within the forest.
• Creating environmental concerns from the excess carbon dioxide (CO2) and carbon monoxide (CO) within the fires’ emissions.

Question 18

European fires

Answer 18

• Russias boreal forests are remote and contain large amounts of accumilated fuel matter, 95% of fires in Russia are in boreal zone
• Across Europe, many forest managers are using prescribed fires to maintain forest ecosystems and to also preventing the encroachment of bush vegetation

Question 19

Impacts of fires in Europe

Answer 19

• Very large source of carbon emmisions
• The carbon stored in the boreal forest accounts for approximatley 37% of the total global carbon pool

Question 20

African fires

Answer 20

• 90% of fires are human-caused
• They are set during the dry seasons to remove any dead vegetation that acciumilates after harvesting as the fires promote new, high-quality growth
• African savannahs contribute to 70% of global fires
• Widespread annual patterns of burnings in the West, East and South of the continent
• Wet African forests have seen a doubling of active fires over 18 years, particularly in the Congo Basin.

Question 21

Impacts of fires in Africa

Answer 21

• Many African plant species and animals have growth and reproduction cycles linked with the fire seasons. Lack of fires harms these species

Question 22

Asian fires

Answer 22

• Fires in SouthEast Asia are affected by El Nino which occurs every year and provides either prolounged dry or wet seasons. If sustained drought occurs, many of the forest vegetation types in SouthEast Asia become vulnerbale to forest fires
• Many fires burn in Chinaeach year even though forests only account for 16.5% of the countries land mass as more than 95% of its fires are attributed to farmers or human carelessness

Question 23

Impacts of fires in Asia

Answer 23

• El Nino was responsible for a massive Southeast Fire which occured in Kalimantan 1997-1998. Economic losses were estimated at $9.3 billion

Question 24

Oceanian fires

Answer 24

• A very fire-prone continent with a diverse range of vegetation types which many are unique to the continent
• Australia is very flat, dry and warm at all times of the year
• Most fires here begin naturally though some Australian afrmers and aboriginal tribes practice some controlled agricultural burning

Question 24

Impacts of fires in Oceania

Answer 24

• Over 18 million hectares have burned in the Australian bushfire season 2019–2020 as of mid-January according to media reports, destroying over 5,900 buildings including over 2,800 homes. In addition to human fatalities, many millions of animals are reported to have been killed.