The forest biome
Biome concepts:
1. Major biological communities, classified by predominant vegetation, physiognomy and environmental
conditions.
2. Discernible at a global scale and their distribution correlates with regional climatic patterns and
identified according to the climax vegetation type.
3. Successional communities: pops of species experiencing non-seasonal, directional and continuous
pattern of colonisation and extinction on a site.
Forest biome characteristics
Dominant vege = trees
- Trees are highly adaptable, from favourable to non-favourable regions
- Physiognomic properties (basis for biome classification):
o Buttress
o Crown
o Nature of levaes
o Nature of forest (evergreen, deciduousness)
o Position of fruit/ flowers
o Nature of bark
o Vertical stratification (3/4 layers)
Closed canopy=survival of understorey trees and ground vegetation
o Large fleshy fruits
o Cauliflory: flowers on stem/trunk
Forests in SA
- Along southern and eastern seaboard and Drakensberg
escarpment
- Highly fragmented (largest = Knysna-Tsitsikamma)
- Other larg forests = Amatole Forest, KZN midlands, Northern
Mpumalanga, Limpopo
Forest classification:
1. Afrotemperate
2. Indian Ocean Coastal Belt Forest
Status of indigenous forests:
- conserved
- Private and tribal ownership
- conservancies and natural heritage sites
- in reserves and=d wilderness = under forest act
Forest floral diversity
- Species decline w/ increasing altitude
- Forests of NE Limpopo > Cape Peninsular
- Indian ocean belt of KZN > Afrotemp at same level and
lower lats
- Coastal & montane of E and W cape < KZN
, Forest structure
Coastal, afrotemp and scarp:
- low in stature (8-25m)
- low species richness
- similar stem densities and basal areas to other African forests
- Basal area/tree = cross-sectional area of tree at breast height
- Basal area/ha = BA of all trees
What separates coastal, afrotemp and scarp?
- Abundance of multi-stemmed species that persist by repeated resprouting
- High resistance and resilience
- Coarse spatial scale/grain
- Large-scale disturbances essential to maintaining coastal forest processes
Forest dynamics:
Why should we understand the dynamics:
- Estimate sustainable levels of resource use
- Blend human impact w/ natural processes
- To answer questions:
o How much can be removed safely in one harvest
o How often can this harvesting intensity be applied
o Which plants can be harvested
o How do they respond to harvesting
o Does sustainable harvesting favour the non-harvested species
Dynamics:
- Gap dynamics
- Windthrow
- Lighting
- Old trees falling over
- Litter fall and nutrient cycling
Paleo-ecological patterns
Role of climate and fire:
Patchy dispersal over landscapes of several biomes shoes their relic-like character
Distribution limits determined by environmental factors (rainfall) w/ fires and winds
Fire does not play a role in the dynamics of the forest
Lightning and human-induced firs exacerbated by the berg winds
Ecology:
Associated with high rainfall >525mm (winter) and >725mm (summer)
Mist supplements rainfall
Found along rivers and protected gorges in areas w/ low rainfall
Biome concepts:
1. Major biological communities, classified by predominant vegetation, physiognomy and environmental
conditions.
2. Discernible at a global scale and their distribution correlates with regional climatic patterns and
identified according to the climax vegetation type.
3. Successional communities: pops of species experiencing non-seasonal, directional and continuous
pattern of colonisation and extinction on a site.
Forest biome characteristics
Dominant vege = trees
- Trees are highly adaptable, from favourable to non-favourable regions
- Physiognomic properties (basis for biome classification):
o Buttress
o Crown
o Nature of levaes
o Nature of forest (evergreen, deciduousness)
o Position of fruit/ flowers
o Nature of bark
o Vertical stratification (3/4 layers)
Closed canopy=survival of understorey trees and ground vegetation
o Large fleshy fruits
o Cauliflory: flowers on stem/trunk
Forests in SA
- Along southern and eastern seaboard and Drakensberg
escarpment
- Highly fragmented (largest = Knysna-Tsitsikamma)
- Other larg forests = Amatole Forest, KZN midlands, Northern
Mpumalanga, Limpopo
Forest classification:
1. Afrotemperate
2. Indian Ocean Coastal Belt Forest
Status of indigenous forests:
- conserved
- Private and tribal ownership
- conservancies and natural heritage sites
- in reserves and=d wilderness = under forest act
Forest floral diversity
- Species decline w/ increasing altitude
- Forests of NE Limpopo > Cape Peninsular
- Indian ocean belt of KZN > Afrotemp at same level and
lower lats
- Coastal & montane of E and W cape < KZN
, Forest structure
Coastal, afrotemp and scarp:
- low in stature (8-25m)
- low species richness
- similar stem densities and basal areas to other African forests
- Basal area/tree = cross-sectional area of tree at breast height
- Basal area/ha = BA of all trees
What separates coastal, afrotemp and scarp?
- Abundance of multi-stemmed species that persist by repeated resprouting
- High resistance and resilience
- Coarse spatial scale/grain
- Large-scale disturbances essential to maintaining coastal forest processes
Forest dynamics:
Why should we understand the dynamics:
- Estimate sustainable levels of resource use
- Blend human impact w/ natural processes
- To answer questions:
o How much can be removed safely in one harvest
o How often can this harvesting intensity be applied
o Which plants can be harvested
o How do they respond to harvesting
o Does sustainable harvesting favour the non-harvested species
Dynamics:
- Gap dynamics
- Windthrow
- Lighting
- Old trees falling over
- Litter fall and nutrient cycling
Paleo-ecological patterns
Role of climate and fire:
Patchy dispersal over landscapes of several biomes shoes their relic-like character
Distribution limits determined by environmental factors (rainfall) w/ fires and winds
Fire does not play a role in the dynamics of the forest
Lightning and human-induced firs exacerbated by the berg winds
Ecology:
Associated with high rainfall >525mm (winter) and >725mm (summer)
Mist supplements rainfall
Found along rivers and protected gorges in areas w/ low rainfall
