Evolution of fire management in Savanna Flashcards
How much of the worlds land surface do Savannas cover?
20%
How much of South Africas land area is covered in Savanna?
35%
Why are Savanna’s beneficial in South Africa?
Tourism and cattle ranching
Why is South Africa prone to fires?
Dry and warm winters combined with an abundance of grass fuels and sources of ignitions (lightning and humans)
Where do trees access water?
Deep soil horizons
Where do grasses access water?
Surface soil horizons
What is considered “stable”?
Maximum woody cover receiving mean annual rainfall of less than 650mm
What is considered “unstable”?
Where the mean annual rainfall exceeds 650mm, sufficient moisture allows trees to attain canopy closure, but is prevented by fire and herbivory
When was the deliberate use of fire introduced?
1981, but it had no guidelines and thus it was haphazard
When was the guide for intentional burning introduced?
In the 1990s
When are fires smallest? Why?
May-june as there is a small amount of fuel
When are fires larger?
August-November
What are the main causes of fire?
Human ignition
Why are unstable ares known as unstable?
The tree layer is not constrained by a lack of moisture, but is prevented from reaching closure because of repeated fires and pressure from herbivores. More rainfall and elimination of fire will result in more fuels
Why are stable areas known as “stable”?
Low rainfall prevents a large build up of fuel
