Course: Geograpy SSE, Topic: UNIT 9: NATURAL VEGETATION OF THE WORLD

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UNIT 9: NATURAL VEGETATION OF THE WORLD
Key unit competence: The student-teachers should be able to appreciate
the distribution of different types of vegetation in
the world.
Introductory activity

Vegetation is important to man in various ways and it acts as habitat place for
wild animals. There is need to conserve it due to its significance. The different
countries have come up with environmental campaigns aimed at protecting
natural vegetation for environment and sustainability.
1. Identify the different types of natural vegetation shown on the map
provided above.
2. Describe the factors influencing the distribution of world vegetation.
3. Why is it important to conserve natural vegetation and how can we
preserve our natural vegetation?
Vegetation refers to a community of plants which grow in an area and which
gives it distinct character. Vegetation in biological terms is known as “flora”,
that is, all vegetation types growing on land and in water.

The world vegetation communities are into categories: forests and grasslands.
They are distributed according to the vegetation zones and they include
tropical, temperate, tundra, desert, mountain and aquatic/marsh or mangrove
vegetation.
9.1. Tropical forests and their characteristics
Activity 9.1
Observe the photograph provided below and answer the questions that follow:

1. Describe the characteristics of the vegetation presented in the
illustration above.
2. What type of vegetation shown in the illustration above basing on
the characteristics described in (1) above?
3. Identify and describe different types of tropical forests.
Tropical vegetation develops within the tropics. Tropical vegetation can be
sub-divided into three but related groups. These include equatorial rainforests,
tropical monsoon forests and tropical mountain forests.

9.1.1. Equatorial forests
The equatorial rainforests grow within the tropics between 10 °N and 10 °S
of the equator. Equatorial rainforests are sometimes called “rainforests”.
Equatorial rain forests cover only a small part of the earth’s surface, which is
about 6% of the earth’s surface. They are situated in Amazon basin in South
and Central America, Congo basin in Central Africa, Malaysia, Burma, and West
African coastal belt (Nigeria, Ghana, Ivory Coast, Liberia and Central Africa
Republic).
The conditions necessary for the growth of equatorial rainforests:
• Equatorial rainforests receive rainfall throughout the year about 2000
mm per year.
• The equatorial rainforests grow in areas with good fertile soils and
well-drained soil.
• The equatorial rainforests require much sunshine to support their
dense growth.
• The equatorial rainforests require temperature about 23-24⁰c.
Equatorial rainforests are characterized by the following:
• Equatorial rainforests are evergreen, since the forests receive heavy
rainfall throughout the year with no clear distinct seasons.
• Equatorial rainforests grow buttress roots in order to support their
enormous sizes.
• The major tree species in equatorial are characterized by a long
gestation period.
• The Equatorial rainforests receive rainfall throughout the year with no
distinctive seasons.
• Vegetation in equatorial regions is comprised of four vertical layers
starting from the canopy of tree to the ferns on ground.
• Equatorial rainforests are dominated with valuable tree species such
as mahogany, ebony, green heart and redwood.
• The forest floor receives low quantity of the sunlight. This has led to
the existence of little undergrowth.
• The trees are very tall (35 m - 40 m) with a very dense and thick
canopy. The result is that the canopy blocks most of the sunlight falling
on them depriving the plants under them of sunlight Most of the trees
in Equatorial rainforests become tall in search of light.
• There are broad-leaved evergreen forests of dense and prolific growth
of flora as well as fauna.
• The major tree species do not grow in pure stands. Trees of pure stands
are scattered all over the forest.
• Beneath the tree canopy exists a well-developed layering of understory
vegetation, which is so dense and this limits light to reach the floor of
the forested area.

The Equatorial rainforests are associated with various economic activities.
These include lumbering as a major activity, provision of local materials which
are used in craft industry, provision of fuel, research and study, provide herbal
medicine, support agriculture, etc.

9.1.2. Tropical Monsoon forests
The Tropical Monsoon Forests found beyond the equatorial region between 10⁰ and 25⁰
Northand South of the equator. This type of vegetation is found in
areas such as; Burma, Thailand, the Indo-China region, parts of India, East Java,
parts of Northern Australia, small parts along the South Western coastal areas
of West Africa.
The conditions necessary for the growth of tropical monsoon forests:
• The tropical monsoon forests receive heavy rainfall, which is around
2000 mm per year. This is received mostly in summer.
• In cooler seasons such as winter, very little rainfall is received. This is
because these regions lie under the offshore trade winds.
• The tropical monsoon forest requires temperatures of about 27⁰c.
This temperature is moderately enough to support the growth of
various plants.

Tropical monsoon forests are characterized by the following:
• The trees possess trunks that they use to store water during the dry
seasons.
• The tropical monsoon forests can grow up to 30 meters in height.
• Trees possess long tap roots that penetrate into the ground to access
groundwater. In order to sustain plants growth, especially during the
dry winter season when there is unreliable rainfall.
• Tropical monsoon forests shade off their leaves during the dry seasons
in order to minimize water loss.
• Trees have broad leaves due to sufficient rainfall (2000 mm) received
during wet season.
• Tropical Monsoon forests experience temperatures that reach 280c
especially in Summer.
• Tropical monsoon forests contain valuable hard wood tree species
such as the teak and sandalwood.
The tropical monsoon forests are associated with various economic activities
such as lumbering on the wider area, agriculture, craft industry, settlement
pattern and provide herbal medicine.

9.1.3. Mountain tropical forests
The tropical mountain forests are mainly located at a high altitude in the
mountains. These usually vary largely along the slopes of Himalayas Mountain
ranges and East African Mountain peaks of Rwenzori, Mt. Kenya and other good
examples include; Cameroon Mountains, and Ethiopia Highlands. The trees
grow in plenty between the altitude 1,500 meters to 3,500 meters. This explains
why such areas are dominated by mountain forests. These have evergreen trees
like Teak, Bamboo, and other tree species such as Pine, Fir, Oak, Maple, Deodar,
Laurel Spruce, Cedar, cedar pod carp and camphor. All these grow abundantly
and dominate the natural vegetation in the area.
The conditions necessary for the growth of mountain forests:
• Mountain forests require much and reliable rainfall;
• Mountain forests require adequate temperature for the growth of tress;
• Mountain forests need deep fertile soil for the growth of forests;

Mountain forests have the following characteristics:
• Mountain forests grow broad leaves and they are evergreen;
• Mountain forests grow thick under growth;
• The forests contain giant evergreen trees that grow on the windward
slopes of the mountain;
• The main tree species are characterized by long gestation period;
The mountain forests are associated with various economic activities such as
lumbering on the wider area, provision of local materials, hunting of animals
and provide herbal medicine.
Application Activity 9.1
1. Briefly explain the geographical conditions that determine the
location of equatorial forests.
2. It has been noted that environment is composed of varieties of
natural resources that support socio-economic development of
any country. Forests fall under such natural resources. Explain
the influence of different categories of tropical forests to the
development of Africa.
9.2. Temperate forests and their characteristics
Activity 9.2
Read the passage provided below and give feedback to the questions that follow:
Temperate forests occur in Eastern North America, North Eastern
Asia, Western and central Europe. Temperate forests are those, which
grow outside the tropics. They are divided into three categories namely
deciduous forests, Mediterranean forests and coniferous forests.
Temperate forests are located between 300 and 700 North and 30 0 and 70o
South of the equator.
1. Identify the types of forests mentioned in the passage above.
2. Compare and contrast the types of forest indicated in the passage
above.
The temperate forests are categorized into 3 categories that include: deciduous
forests, Mediterranean forests and coniferous forests.
The conditions necessary for the growth of temperate forests:
• Temperate forests need little supply of sunshine for the successful
growth.
• Temperate forests require enough fertile soil and availability of water
for growth.
• Temperate forests require amount of rainfall about to 750 mm in dry
period.

The characteristics of temperate forests
• With high levels of precipitation, humidity, temperate forests have a
variety of deciduous trees.
• Trees shed their leaves in fall in winter and bud new leaves in spring
when warmer temperatures and longer hours of daylight return.
• Temperate forests have tall evergreen trees dominating the regions.
• They have Redwood trees which are the tallest in the world, the most
prominent tree type in temperate forest is Douglas.
• Temperate forests have epiphytes species such as mosses and ferns
that live on the branches and trunks of trees, especially the broadleafed maples.

The temperate forests are associated with various economic activities. These
include tourism which is supported by the presence of many different species
of birds such as like broad-winged hawks, cardinals, snowy owls, and pileated
wood peckers that attract very many people from different parts of the world.
There is also hunting due to different types of animals such as white-tailed deer,
raccoons, opossums, porcupines and red foxes.
9.2.1. Mediterranean forests
The Mediterranean forests are located mainly in South West America, Spain, Italy,
France, Australia, Algeria, Morocco, Tunisia, and Central Chile. Mediterranean
forests grow also well in South Africa near Cape Town.
• Mediterranean vegetation is characterized by open and evergreen woodlands.
• Mediterranean vegetation has deciduous tree species with long
gestation period and thicket with thin and waxy leaves.
• They are composed of broadleaf trees, such as the oak and mixed
sclerophyllforests.
• Mediterranean vegetation has dense foliage composed of broadleaved
evergreen shrubs, bushes, and small trees. There is inadequate undergrowth.
Tall trees grow in regions lying between 30° and 40° North and South latitudes
• There are woody, evergreen shrubs or small trees that have developed
various strategies of growth and usage of available water during the dry period.
• Mediterranean plants have long taproots to reach underground water,
called “Xerophytic Plants”.
• Mediterranean trees adapt themselves to dry summers with the help
of their thick barks and wax coated leaves. These reduce the rate of transpiration.
The Mediterranean forests are associated with various economic activities
such as mining of oil, tourism, and very limited population settlement. There is
also rearing of sheep and growing of crops such as wheat, oats and cultivation
of chestnuts.
9.2.2. Coniferous forests / Taiga Forest
The coniferous forests are located across North America, Europe, and Asia.
These forests are found within the extent of 50˚ to 60˚N. The coniferous forest
is the largest terrestrial vegetation covering about 17% of Earth’s land area.
Countries such as Canada, Russia, and Scandinavia are almost entirely covered
by these coniferous forests. The vegetation is identified by its climate, which
occurs almost exclusively in the high latitudes of the Northern hemisphere.
Coniferous forests are favoured by the following environmental conditions:
• The coniferous forests require inadequate supply of sunlight.
• The coniferous forests need medium fertile soil with availability of water.
• The coniferous forests grow well with an average temperature of
below 43⁰ F during the winter season.

The characteristics of coniferous forests are:
• The coniferous forests consist of tall, straight and softwood evergreen
trees with few branches.
• There are limited species of trees. The existing trees are evergreen and grow apart.
• The type of trees in these coniferous forests grow in pure stands, to a
height of over 30m.
• Trees are conical shaped with needle-like leaves. These include firs,
pine and cedar which are important variety of trees in these forest.
• Coniferous tree species grow shallow roots and can collect enough
water from top soil;
• They have shallow roots used to absorb the nutrients and water from
the top soil;
• The coniferous vegetation has adapted to harsh conditions associated
with winter season.
• Leaves are small, narrow with the capacity of reducing transpiration.
The coniferous forests are associated with various economic activities
which include lumbering, tourism, apiculture (bee keeping), hunting, herbal
medicines, fruit gathering and Research and study.

9.2.3. Deciduous forests
Deciduous forests grow well within the latitude of 40° N and 60°N and 30° S and
50oS of the equator. Deciduous forests can be found in the Eastern half of North
America, and the middle of Europe. There are many deciduous forests in Asia.
Some of the major areas having deciduous forests include, Southwest Russia,
Japan, and Eastern China. South America has two big areas of deciduous forests
in Southern Chile and Middle East coast of Paraguay. These are also located in
New Zealand and South Eastern Australia also.
The conditions necessary for growth of deciduous forests:
• Deciduous forests require moderately distributed rainfall.
• Deciduous forests need low sunshine supply.

The characteristics of deciduous forests:
• Trees shed their leaves in the dry season to conserve water.
• Deciduous forests are characterized by existence of epiphytes, which
include mosses.
• They contain hard wood trees like sandalwood, maple, oak, beech,
teak, ebony, bamboo, etc. which are the common trees found here.
They require low sunshine supply.
• Deciduous forests grow in pure stands, have a short growing gestation.
The deciduous forests are associated with various economic activities which
include lumbering, tourism activity, hunting, herbal medicines and fruit gathering.

Application Activity 6.2
Identify the characteristics of Mediterranean forests.
9.3. Grasslands in tropical zone and their characteristics
Activity 9.3
Observe the photograph provided below and answer the questions that follow:

1. Referring to your observation, describe the characteristics of the
grassland shown above.
2. Suggest two world areas where such presented vegetation is found.
3. Distinguish savannah humid from savannah dry grasslands.
Tropical grasslands are commonly known as savannah vegetation. Tropical
grasslands grow well within altitude of 5⁰ N and 15^o N and 5⁰ S and 15^o S of
the equator. Tropical grasslands grow well in Africa, South America specifically
in Campos in Brazil”. They can also be found in Guyana, Australia, Eastern
Madagascar and India. Tropical grassland is divided into two groups: Savannah
and steppe.
9.3.1. Savannah humid vegetation
Savannah humid forests grow well in regions experiencing the average total
rainfall of 1000 mm per year. Miambo woodlands of central Tanzania is one
of the examples of savannah woodlands in East Africa. Other examples of
savannah humid are found in Madagascar, Indian subcontinent, South East Asia
and New Guinea.
The conditions necessary for the growth of Savannah humid vegetation:
• The savannah humid can grow well in regions experiencing
temperatures ranging between 25⁰C to 32⁰C.
• Savannah humid vegetation grows well in areas which experience
rainfall about 750 mm to 1000 mm per annual.
• Savannah humid needs maximum sunshine and light necessary for the
plants to make chlorophyll.

The characteristics include the following:
• The tree species are deciduous, and shade leaves during the dry periods.
• The Savannah vegetation is mostly characterized by undergrowth
dominated by shrub and short grasses.
• The species of trees such as baobab and acacia are mostly common in area.
• The grass can grow very tall, about 3 to 4 meters in height. The common
type of grass is known as “elephant Grass.
• Most tree species in the savannah woodlands form small umbrella.
• The non-thorny trees such as baobab, candelabra, and the Jackal berry
are found in savannah grasslands
The Savannah humid vegetation is associated with various economic activities
such as; hunting, herbal medicine collection, fruit gathering, rearing of animals
and subsistence farming, settlement, mining and gazetting of national park and
game reserves.

9.3.2. Steppe/ Savannah dry vegetation
Savannah dry covers almost half the surface of Africa (central Africa) and large
areas of Australia, South America, and India. Climate is the most important
factor in creating a savannah dry vegetation. Savannahs are always found in
warm or hot climates where the annual rainfall is from about 508 to 1270 mm
per year. These regions receive rainfall for about 6 to 8 months. This is followed
by prolonged dry period that is usually affected by fire out-breaks.
The conditions necessary for growth of Savannah dry/steppe vegetation:
• The soil which is dry and porous, with rapid infiltration of water.
• Dry climatic conditions that support the growth of different grasses
due to disparities in rainfall and soil conditions.
• Availability of average annual rainfall of 762-1016 mm.
• Presence of soils that are too thin. Trees require the existence of
termite mounds where they grow.

The main characteristics of Savannah dry vegetation are:
• The trees and grass grow through direct competition for water, light and nutrients.
• The open canopy allows sufficient light to reach the ground to support
an unbroken herbaceous layer consisting primarily of grasses.
• Annual herbaceous plants die completely at the end of the growing
season or when they have flowered and fruited. These grow again
from seed when the wet season sets in.
• The vegetation consists of tall grasses of two high or more and scattered
trees.
• The trees lose their leaves in dry season and are mainly found near
watercourses. The main types of tree species are acacia.
• Some plants have thick barks and thorny leaves to reduce water loss.
The Savannah dry /steppe vegetation is associated with various economic
activities including hunting, fruit gathering, rearing of animals, settlement,
agriculture and gazetting of national park and game reserves.
Application Activity 9.3
1. Describe savannah grasslands with reference to South Africa.
2. With reference to Rwandan context, explain the importance of
savannah grasslands in the economic development.
9.4. Temperate grasslands and their characteristics
Activity 9.4
Study the picture provided below and answer the questions that follow:

1. Observe the picture provided and explain the conditions necessary for
the growth of the vegetation shown above.
2. Suggest any two-world areas where the vegetation presented above is found.

Temperate grasslands are known by different names in various regions.
“Prairies” in North America; “Pampas” in South America (Argentina), “Downs”
in Australia “Velds” in South Africa and “Steppes” in Europe. These are found
in the mid- latitudinal zones and in the interior part of the continents. The
Temperate grasslands are found in Central Asia from Black Sea to Central Russia,
North Central USA and Southern Canada, South-East Australia, Southern Africa
and Argentina.
The conditions necessary for growth of temperate grasslands:
• Temperate grasslands require minimum light for the plants to make their own food.
• The temperate grasslands require moderate fertile, fine drained and humid soil.
• Temperate grasslands need average sunshine in dry and cool winter time.
• Temperate grasslands require moderate rainfall of about 500 mm -
750 mm for best growth of grasslands.

The characteristics of temperate grasslands are:
• Grasslands found here are short and juicy which is suitable for cattle feed.
• The region is known of growth of maize and wheat in large amount.
This explains why, the area is known as “bread basket” of the world.
• The perennial temperate grasses mostly belong to the family of “Gramineae.”
• The steppes form the largest segment of the temperate grassland
biome. Steppes are divided into: Forest steppes, Meadow steppes and grasses.

The temperate grasslands are associated with various economic activities which
include: hunting, fruit gathering, rearing of animals, settlement, agriculture and
gazetting of national park and game reserves.
Application Activity 9.4
Assess the contribution of Temperate grasslands to the economy of the
countries where they are found.
9.5. Desert vegetation and its characteristics
Activity 9.5
Observe critically the photographs provided below and answer the
questions that follow:

1. Identify the nature of the types of vegetation in these two figures above.
2. Compare and contrast the geographical conditions shown on both figures.

Desert vegetation grows in the Western margins of the continents between 15°
– 30° North and South of Equator. Biggest deserts are: Sahara and Kalahari in
Africa, Thar in India, Arabia desert covering the countries of Saudi Arabia, Iraq,
Iran, Syria and Israel, Atacama Desert (Peru and Chile), Southern California in
USA, Sonora in Mexico and Victoria in Australia. Desert Vegetation is divided
into two types, namely hot desert and cold desert vegetation or Tundra.
9.5.1. Hot desert vegetation
Hot deserts are located between the latitudinal belts of 15°-30° North and South
of the equator. These deserts can be found in North America, South Asia, South
and Central America, Africa and Australia. Hot desert vegetation experiences
hot climatic conditions throughout the year. The rainfall is unreliable. This is
caused by the dry winds that blow over the area, leading to arid conditions.
Such conditions leave behind very poor vegetation in the desert region.
The conditions necessary for growth of hot desert vegetation:
• The presence of poor quality and infertile soils.
• Availability of rainfall total of about 250mm or less per year.
• The prevailing of high temperatures ranging between 29⁰c and 31⁰c to
support the growth of plants associated with arid areas like deserts.

Hot desert vegetation is characterized by the following:
• There are a few plants with succulent stems, long roots and leaves.
• The desert trees shed off their leaves occasionally primarily to
minimize on water loss from the excessive temperature.
• Desert vegetation types especially the tree species grow long tap roots
to have access to water that is found deep in the underground water table.
• The main vegetation growing here is mainly thorny acacia, bushes,
euphorbia and turfed coarse grasses.
• Some desert vegetation types grow no leaves in order to avoid excessive
water loss through evapotranspiration.
9.5.2. Cold desert vegetation
The cold vegetation is located in high flat areas called plateaus. It is also common
in mountainous areas in temperate regions of the world. Temperate regions lie
between the Polar Regions and the tropics. Like other types of deserts, cold
deserts get very little rain or snow and are mainly in the Northern part of
Canada, North Russia, North Sweden and Finland islands in Arctic Ocean.
The conditions necessary for growth of cold desert vegetation:
• Cold desert vegetation needs low sunshine for its successful growth.
• It requires a combination of freezing temperatures, poor soil quality,
lack of moisture and sunlight.
• This vegetation requires soils associated with relatively high soil salinity.
• Cold desert vegetation needs very little rain fall of about 250 mm
during the summer season and snowfall during the winter.
• It requires areas characterized by frost conditions.

The major characteristics of cold desert vegetation include the following.
• The main plants are deciduous widely scattered and most having spiny leaves.
• The cold desert vegetation grows in areas with large amount of
snowfall in winter (and sometimes in summer).
• The cold desert vegetation experiences short and wet moderately
warm summers.
• This vegetation receives a mean annual precipitation that ranges from
90 mm to 260 mm, and the mean average winter temperature ranges
from -2 to 4 degrees.
• The cold desert vegetation does well in areas with good drainage that
facilitates leaching of most of the salts.

The cold desert vegetation is associated with various economic activities that
include tourism, mining and agriculture on small scale and establishment of
national park and game reserves.
Application Activity 9.5
Referring to Sahara Desert, describe the impact of desert vegetation and
climatic conditions on the population settlement in any country around it.
9.6. Tundra vegetation
Activity 9.6
Observe the provided picture below and answer the following questions

1. Identify the type of vegetation shown on the photograph above.
2. Explain the characteristics of the vegetation identified in (1) above
Tundra vegetation is found in coldest regions of the world. The term tundra is
derived from the word “tunturi” (from Finnish language) which means “treeless
plain.” This vegetation is found in the arctic region on top of mountains where
climate is cold, windy and with limited rainfall. The tundra vegetation is found
in regions that cover the areas of Alaska, parts of Russia, Northern Scandinavian
countries and some parts of Canada.

The following are conditions necessary for the growth of tundra vegetation:
• The Tundra vegetation requires winters that are cold, long and dark.
• It does well in regions that experience about 6 to 10 months with
monthly temperatures below 32° F or 0° c.
• This vegetation needs limited precipitation and existence of strong and dry winds.
• It requires snowfall conditions that support the survival of plants and
animal life. At the sometimes, acts as a protection layer on the surface of the ground.
The characteristics of tundra vegetation are the following.
• The vegetation arrangement is simple and there is limited variety of trees.
• The season of growth and reproduction is short.
• The drainage system is nearly limited.
• The nutrients and energy here is in form of dead and organic material.
The tundra vegetation is associated with various economic activities that
include tourism which is associated with the following tourist attractions: Birds
like ravens, falcons, snowy owls and snow geese and animals such as foxes,
wolves and some smaller mammals like the lemmings and snowshoe rabbits.
These areas also, support hunting, oil exploitation and research and study.
Application Activity 9.6
For either Russia or Canada, describe the necessary geographical
conditions for the growth of tundra vegetation in that country.
9.7. Mountain vegetation and its characteristics
Activity 9.7
Using your previous knowledge and geographical sources, answer the
following questions:
1. Describe mountain vegetation in tropical zone.
2. Describe the characteristics of mountainous vegetation with
reference to East Africa.
Mountain vegetation is categorized into two types; namely, tropical mountain
vegetation and temperate mountain vegetation.

9.7.1. Tropical Mountain vegetation
Mountain vegetation has a variety of vegetation ranging from tropical to
temperate types. On typical Mountain slope, various vegetation types show
clear demarcation zones. The savannah vegetation grows from the foothills,
followed by the layer of tropical rainforests, bamboo forests, mountain heath
and moorland. The rest is bare rock. This type of vegetation is traced in areas
such as: Mt. Kenya, Mt. Aberdares, Mt. Kilimanjaro, Mt. Meru, Mt. Elgon, Mt.
Cameroon, Mt. Ruwenzori, Mt. Virunga, Mt. Simien and Mt. Bale.
The conditions necessary for growth of mountain vegetation
• This type of vegetation requires the steep gradient.
• It needs well distributed rainfall characterized by humid conditions.
• It grows well in areas which generally are associated with strong
seasonal differences.
• It requires temperature ranges of about 20° C at 900 m and 4°c in the
summit region.
• It requires the annual precipitation of around 900 mm on the foothills,
around 2000 mm at 1500 m and well above 3000 mm between 2000
and 2300 m on a windward side.
• It requires fertile soils that are well-developed with moderately acidic
soil pH values, such as Andisol.

The characteristics of mountain vegetation
• The vegetation on the mountain slope grows in clearly demarcated
zones from the foothills to the summit.
• Mountain vegetation is dominated by tussock grasses and stands of
giant rosette.
• The mountain heath and moorlands grow between the bamboo forests
and the snow-line or bare rocks.
• The tree species, mainly of the lower canopy are the wild olive.
• Soils in the mountains are mostly young and fertile which favours the
growth of trees.
• Above snow-line, plant life is always impossible. This is attributed to
low temperature and the presence of eroded bare rocks that makes it
hard for plant growth.
• In mountainous areas, the decrease in temperature with increasing
altitude leads to the corresponding change in natural vegetation.
• The wet temperate forests are suitable between 1000 and 2000 mm.
• Temperate forests containing coniferous trees like pine, deodar, silver
fir, spruce and cedar are found between 1500 and 3000 mm.
The mountain vegetation is associated with various economic activities. These
include gazetting of national park and game reserves, tourism etc.

9.7.2 Temperate mountain vegetation
Temperate mountain vegetation grows well in High Mountain of temperate
regions. This grows best between 35⁰ N and 60⁰ N of the equator.
Temperate mountain vegetation is in the Alps, in Western Europe, in Norway,
Sweden and Finland. Other traces of temperate mountain vegetation can be
found in California on the Rocky Mountain slopes, British Columbia and Andes
in South America.
The characteristics of temperate mountain vegetation
• Temperate mountain vegetation contains both deciduous and
coniferous plant species such as poplar, birch, oak and elm.
• Some trees species grow a thick bark in order to store enough water to
be used in winter season.
• Tree species shed-off their leaves in winter when temperature drops below 6° c.
• Tree species especially the coniferous forests adapt themselves to the
climatic conditions by growing tiny needle-like leaves.

Application Activity 9.7
1. Explain the use of mountainous vegetation with reference to Northern Rwanda.
2. Critically examine the role of temperate mountain vegetation to the
economy of Switzerland
9.8. Aquatic, marsh and swamp vegetation and their characteristics
Activity 9.8
Make a critical analysis of the photo below to answer the questions that follow:

1. Identify the type of vegetation shown on the photograph above.
2. From your own observation describe the environmental conditions
that influence the location and growth of the identified vegetation above.

1) Mangrove vegetation
This is the type of vegetation that grows in marshy and swampy areas along the
coast of West Africa and East Africa. The Mangrove vegetation is evergreen and
grows along the coastal margins between 5^o N and 5^oS of the equator.

The conditions necessary for growth of mangrove forests:
• They need average temperatures of the coldest month higher than
20°C. The seasonal temperature range should not exceed 5°C. They
can tolerate temperatures of 5°C, but the development will be affected.
This is because they are not resistant to freezing.
• They need a large tidal range. This causes limited erosion and
deposition of sediments.
• They need a fine-grained substrate. However, there could be some
exceptions. This is the case in Papua New Guinea and Kenya, where
the mangroves grow on corals.
• The shores must be free of strong wave action and tidal current.
• Mangrove vegetation requires swampy and marshy areas with deep
soils which must be salty in nature.
• Mangrove vegetation requires high temperature necessary for
chlorophyll making.

The characteristics of mangrove forests:
• Mangrove vegetation has broad branches and leaves and they are
evergreen, dominated by trees.
• They are associated with saline soils with poor drainage.
• The mangrove vegetation grows butters root.
• This type of vegetation has a long gestation period.
• They exist in areas with poor drainage and sufficient water supply. Such
areas are waterlogged that are hypoxic (oxygen deficient) waterlogged soil strata.
• Mangrove forest species, survive under temperatures above 66°
F (19°C). They do not tolerate temperatures below 18° F (10° C).
However, temperatures below freezing should not occur for a long time.

2) Aquatic plants:
The aquatic plant vegetation is referred to as hydrophytes or macrophytes.
These plants require special adaptations for living submerged in water, or at
the water’s surface. Aquatic plants can only grow in water or in soil that is
saturated with water.

The following are Characteristics of aquatic plants:
• These have reduced and shallow roots. The primary function of these
roots is to anchor the plant to the ground.
• Plants that normally are submersed typically form their flowers raised
above the water surface.
• Some of the aquatic plants float on the surface of water with no
attachment to the mud or bottom. These have inflated portions of
leaves, stems, or special hairs that enable the plant to remain floating.
• Plants rooted in the mud have immersed leaves with photosynthetic
stems. They also have relatively small leaves similar to those of typical
leaves of terrestrial plants living nearby?
Marsh vegetation:
A marsh is a wetland that is dominated by herbaceous rather than woody plant
species. Marshes can often be found at the edges of lakes and streams. In such
places they form a transition between the aquatic and terrestrial ecosystems.
Marsh vegetation is dominated by grasses, rushes or reeds. Familiar examples
of marsh vegetation include cattails, sedges, papyrus and sawgrass.

The following are characteristics of a marsh
• The marsh vegetation is a common characteristic of wetlands areas
and grows in poorly drained water.
• The marsh vegetation grows in both fresh and salty waters.
• The marsh vegetation is found along the rivers and lakes.

Swamp Vegetation
Swamp vegetation occurs along large rivers where they are critically dependent
upon natural water level fluctuations. When a swamp vegetation is dominated
by forest, it is called a wetland. Some swamps have hammocks, or dry-land
protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic
inondation.

Characteristics of swamp vegetation are:
• They are characterized by poorly drained soils and different plant life
dominated by trees.
• The later characteristic distinguishes a swamp from a marsh, in which
plant life consists largely of grasses.
• They grow in waterlogged areas where there is sufficient supply of
water, that allows or stimulate decay of organisms and prevent the
accumulation of organic materials.
• They are often found in lowlands associated with rivers that supply
the water to some lakes.
• The number of plant species in swamps is less. While the one found
in areas associated with well-watered conditions and no waterlogged
land, has more plant species.

All the swamp vegetation such as mangrove, marsh, wetlands and aquatic
forests, are associated with various economic activities. These include tourism,
hunting and fishing of crayfish and mudfish. They are also used for research
and study purposes. These support art and craft making.
Application Activity 9.8
1. Explain the conditions that favour the growing of mangrove
vegetation in West Africa.
2. Examine the economic importance of mangrove vegetation to man.
9.9. Factors influencing natural vegetation
Activity 9.9
Make a field trip in your home area and observe types of vegetation. Use
the results of your observation to explain the factors influencing their
distribution.

There are various factors that influence the growth and distribution of natural
vegetation. There is no single factor that plays a key role alone, but rather a
combination of two or more factors. These factors include the following:
• Rainfall: Growth of vegetation depends on amount of rainfall. For
example, Equatorial rainforests have evergreen and dense vegetation.
On the other hand, places with low rainfall have scattered vegetation.
This explains why there is little vegetation in deserts.
• Temperature: Forests found in cool areas have fewer tree species.
Those in hot areas have more species. The cold mountain tops have
heath and moorland.
• Relief and altitude: It has been noticed that with a rise in the altitude,
the plants in the region show a stunted growth. Trees such as pine,
silver fir, birch, and juniper fall in this category of vegetation. These
contribute to variation in vegetative zonation along the slope.
• Slopes: Areas on the opposite sides of mountains have different
vegetation. Steep slopes have more runoff. Gentle slopes allow water
to sink into the soil. Plants use this water.
• Soil types: This factor provides basis for different types of vegetation.
The sandy soils in the desert support cactus and thorny bushes. Wet,
marshy or delta soils support mangroves and other deltaic vegetation.
• Human activities: These include settlement, mining, farming and
livestock keeping. For example, vegetation is cleared to create space
for building houses. Trees are cut for firewood and timber. New or
artificial vegetation is planted.
• Drainage: It determines the vegetation of a place. There are plants
that grow best in areas of good drainage while others grow well in
swampy conditions for example papyrus which only grows in swampy area.

Application Activity 9.9
Describe the influence of human activities on vegetation distribution in Rwanda.
9.10. Importance of the natural vegetation
Activity 9.10
Make a field trip in your home area, observe nature of vegetation and explain
the significance of it to man.
The following are the significance / importance of vegetation to man:
• Plants that form vegetation are the main source of food for humans.
These foods are in form of vegetables, fruits, grains, cereals, leaves,
seeds and they comprise of carbohydrates, oils, proteins, vitamins and
minerals. Vegetation also provide foods for domestic and wild animals.
• Provide construction materials for example, trees are used for the
construction of houses, bridges and poles.
• Vegetation helps to regulate the flow of numerous biogeochemical cycles
in the atmosphere. Most critically those of water, carbon, and nitrogen. It
also contributes in the local and global energy balances.
• Vegetation plays an important role in our ecosystem. Whereby, plants
are known as the primary producers since they can manufacture their
own food through the process of photosynthesis using sunlight.
• The natural vegetation provides man with a variety of products which
include flowers, stems, roots, oil and many others. These are used to
meet man’s needs such as in making of perfumes, cosmetics and aesthetic purposes.
• Vegetation has contributed hugely to the world economy, particularly in
the use of fossil fuels as an energy source. It provides biomass and some
vegetation residuals are used to produce biogas.
• Vegetation provides timber for furniture. Items as beds, chairs and tables
are made from timber. Timber is also used in construction activities.
• Vegetation plays a key role in the formation of soils. Their roots facilitate weathering.
• Dead vegetation becomes humus, which makes the soil fertile.
• Vegetation is also a natural resource, which provides number of uses to
man. That is to say, products such as ropes, rubber, gum, papers, and wood
are obtained. These are used in manufacturing of materials like books, rope,
tyres, and seats.
• Some plants have medicinal content. These herbs are used in treatment of
various diseases that threaten human lives as well as those of domesticated animals.
• Vegetation is source of materials such as cotton. This is used in textiles and
fabric materials used in making of clothing for human use.
• Vegetation such as forests and grasslands attract tourists. These pay
(money) when they visit to see the animals and a variety of flora. The money
is used to develop the social facilities such as schools, hospitals etc.
• Vegetation helps to clean or purify air through harvesting carbon dioxide
from the atmosphere. Again, trees produce oxygen that human beings and
animals use for survival.
• Places with forests receive more rainfall. This is through the process of transpiration.
• Areas with forests act as sources of rivers. These are called water catchment areas.
• Many people get jobs. They are employed as researchers, forest guards and
forest officers.
• Vegetation makes the landscape beautiful.
• Tree and plant roots hold the soil together. Therefore, forests protect the
ground (soils) against soil erosion, mass wasting and the general impact of
heavy rainfall.

Vegetation has also negative influences to man which are the following:
• Vegetation is associated with some pests such as tsetse flies and ticks
which put the lives of people and animals at great risk, since they cause diseases.
• Some plants are thorny-leaved and they are harmful to human beings
and animals.
• Vegetation is a habitant place for dangerous animals which may attack
or harm human being.
• Some plants are poisonous and may kill human being and animals when eaten.

Application Activity 9.10
Examine the value of natural vegetation for sustainable development of
the country.
Skills lab
Vegetation plays a great role in daily life. Identify any type of vegetation and
link it with the appropriate economic activity in the local community.
End unit Assessment
1. Discuss the distribution of natural vegetation in the world.
2. Describe the relationship between vegetation and land use.
3. Draw a map of the world and on it, show the following vegetation types:
• Savannah humid
• Mediterranean vegetation
• Desert vegetation
• Mountain vegetation
4. How do the following factors influence the distribution of vegetation in Africa?
• Variation in temperature.
• Variation in relief

Geograpy SSE

General

UNIT 9: NATURAL VEGETATION OF THE WORLD

UNIT 9: NATURAL VEGETATION OF THE WORLD

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