Examine the influence of altitude on vegetation zonation in the highlands of East Africa. 

• Candidates are expected to define vegetation zonation, identify the highlands of East African then illustrate the vegetation zones on the highlands of East
• Candidates should identify the vegetation types; describe their characteristics and explain the conditions for their existence at the given altitude

 

Vegetation is a continuous plant cover.

Vegetation changes from the bottom to the top of highlands in such a way that the types of vegetation can be identified.

Highlands of East Africa include Mt. Kenya, Mt. Rwenzori, Mt. Kilimanjaro, etc.

Role of altitude on vegetation zonation on highlands of East Africa

Vegetation zones on the above highlands can be illuslr8ted as follows.

Attitude influences the above vegetation zonation in the following ways:

At the height of between 1000m-1800m above sea level, there is savanna vegetation e. grassland vegetation and woodland.

Savanna grassland is characterized by:­

• Tall grass e.g. elephant grass
• scattered trees
• grass dries during the dry season
• there is a lot of scrub, bush and thickets with stunted vegetation.

This is because at this altitude there is:

• low rain fall of less than 750mm
• low humidity of less than 40%
• hot temperatures of about 29°C
• Fairly fertile soils
• human interference like mining cultivation, settlement etc.

This is followed by savanna woodland characterized by :

• More trees which are umbrella shaped
• Trees are deciduous,
• Trees are drought resistant with swollen trunks , small leaves to control water loss etc.

This is due to the following conditions:

• moderate rain fall of about 1000mm
• Hot temperatures of about 27°- 29°C moderate humidity
• fairly fertile soils and well- drained soils
• At an altitude of between 2000m- 2500m above sea level, rain forest exist.

This is characterized by:

• tall trees of about 50m,
• evergreen trees with broad leaves
• buttress roots , climbing plants like lianas etc.

This is due to the following conditions:

• heavy rain fall of between 1500 -2000mm
• hot temperatures of about 27°C
• deep and fertile soils
• less human interference
• well drained soils .

At an altitude of between 25000m-3000m above sea level; temperate forests exist although not common to all highlands of East Africa

They are characterized by:

• soft wood trees like pine, camphor trees
• have small leaves
• trees are evergreen
• trees are conical in shape
• needle shaped leaves etc.

This is due to:

• reducing rain fall totals
• cool temperatures
• shallow/ thin soils
• well drained soils.

At an altitude of 3000m 3500m above sea level, bamboo forests exist.

These are characterized by:

• segmented stems that are hollow
• small tough pointed leaves, evergreen trees
• have prop roots
• appear in single layers

This is due to the following conditions

• cold temperatures /cool temperatures
• reduced rainfall
• thin soils
• well drained soils

Between 3500m -4500mabove sea level. Heath and moorland exists.

These are characterized by short grass

• Alpine shrubs /bushes
• Everlasting green flowering plants.
• Plants like groundsel, lobelia

At an altitude above 4500m above sea level mosses, lichens exist

This is due to the following conditions

• cold/ cool temperature
• extremely low rain fall or no rain fail
• very thin soils
• Poorly drained soils due to melting of snow