| Tropical
continental ecosystem
By
Marjorie Henry, Contributor
 |
| Jamaica
College students walk past this saxophonist who was performing at Matilda's Corner
recently. - Nathaniel Stewart/Freelance Photographer | In
the last lesson, I began to review the tropical continental ecosystem. The location
and climatic characteristics were looked at in that lesson. Remember that the
ecosystem is influenced by climate, and also that the plant life is an integral
link in it. So, today, the vegetation associated with this ecosystem will be the
focus of the lesson. Before doing this, however, let me give the expected responses
to the questions given in the previous lesson. These are as follows: 1.
The tropical continental climate is best developed in The Sudan, in Africa. 2.
The names of the tropical continental climate in South America are the llanos
of the Orinoco Basin and the campos of the Brazilian highlands. 3.
The climate is characterised by an alternate hot, rainy season and cool, dry season.
4. The
'Harmattan' refers to the dry, hot, dusty winds that blow from the Sahara Desert
during the dry season. They are particularly noticeable in West Africa. 5.
The climate experiences the highest temperatures just before the onset of the
rainy season. 6.
The clear sky that promotes intense heating during the day also causes rapid radiation
in the night. This results in an extreme diurnal range of temperature. I
do trust that you made the effort to go through the questions and that you were
able to find the correct responses to them. Let
us now turn our attention to the vegetation of the region. Since the tropical
continental climate is characterised by an alternate hot, rainy season and cool,
dry season, the vegetation found there must be able to survive in this climatic
condition. The text informs us that the vegetation that do well in this climate
have features, which help them to make good use of the limited water in the dry
season; or have a seasonal pattern of growth, and become dormant during the annual
drought. The
characteristics of the vegetation include the following: -
One common type of vegetation is tropical grassland or savanna.
-
Tall grass and short scattered trees, transitional between that of the hot desert
and the tropical forest, typify the vegetation.
- Trees
are always present amongst the luxuriant tall grasses, and the terms, 'parkland'
or 'bush veld', are often used to describe the natural vegetation.
-
Equatorwards, the trees increase in size and density owing to an increase in annual
rainfall and a less distinct dry-wet climatic rhythm. But, desertwards the vegetation
merges into scrub and thorny bushes.
Mention
was already made of the nature of the vegetation that would do well in the tropical
continental ecosystem. The question can then be asked, how are the trees and plants
adapted to the savanna climatic rhythm of long winter drought and short summer
rain? Several ways have been identified. -
Trees and plants are deciduous in nature, shedding their leaves in the cool dry
season to prevent excessive loss of water through transpiration and lying dormant
during the long drought.
-
They have long roots (e.g. acacias) to search for groundwater or broad trunks
(e.g. baobabs and bottle trees) to store excessive water.
-
Trees are mostly hard, gnarled and thorny, and may exude gum (e.g. gum Arabic).
-
Many trees are umbrella-shaped to shield their roots from the scorching heat and
to expose only a narrow edge to the strong trade winds that blow all year round.
-
The grasses are usually tall and coarse, growing two to four metres (six to 12
feet) high, and they grow in compact tufts. They have long roots, which reach
deep down to the moist rock layers in search of water.
In
the next lesson, I will go on to the tropical marine ecosystem. As usual, I encourage
you to do some reading on the topic. References:
General
Geography in Diagrams by R. B. Bunnett
Certificate
Physical and Human Geography by Goh Cheng Leong
The
Caribbean Environment by Mark Wilson Marjorie
Henry teaches at Glenmiur High School. | 
