Fire
Fire acts as a large herbivore with similar vegetation dynamics
The difference is that fire competes with, replaces and facilitates vertebrate herbivory
Fire prone vegetation
- Arid savanna
- Arid grassland
- Mesic grassland
Fire determinants
- Amount of fuel load (grassy = savanna/grassland, woody = fynbos)
- Composition & structure of plants
o Moisture content
o Oils, terpenes
o Fine leaves
o Species composition
o Shape and arrangement of plants
- Climate (hot/ dry weather w/ wind)
- Ignition (lightning, rock fall, humans)
Fire regime
Consists of:
1. Fire frequency
o Depends on fuel accumulation, climate and ignition
o Time since last burn (grasslands = 1-3 years, savanna = (BL) 3 years and >5 years
(arid), fynbos = 15-50 years)
2. Fire type
o Savanna and grassland = surface fire
o Fynbos = crown fire
o Ground fires absent in SA
3. Fire intensity
o Determine vegetation recovery
o Depends on rate of spread and available heat combustion
o Grassland < savanna < fynbos
o Flame length = predictor of tree-kill
4. Fire seasonality
Fire acts as a large herbivore with similar vegetation dynamics
The difference is that fire competes with, replaces and facilitates vertebrate herbivory
Fire prone vegetation
- Arid savanna
- Arid grassland
- Mesic grassland
Fire determinants
- Amount of fuel load (grassy = savanna/grassland, woody = fynbos)
- Composition & structure of plants
o Moisture content
o Oils, terpenes
o Fine leaves
o Species composition
o Shape and arrangement of plants
- Climate (hot/ dry weather w/ wind)
- Ignition (lightning, rock fall, humans)
Fire regime
Consists of:
1. Fire frequency
o Depends on fuel accumulation, climate and ignition
o Time since last burn (grasslands = 1-3 years, savanna = (BL) 3 years and >5 years
(arid), fynbos = 15-50 years)
2. Fire type
o Savanna and grassland = surface fire
o Fynbos = crown fire
o Ground fires absent in SA
3. Fire intensity
o Determine vegetation recovery
o Depends on rate of spread and available heat combustion
o Grassland < savanna < fynbos
o Flame length = predictor of tree-kill
4. Fire seasonality
