| The
ecosystem
By
Marjorie Henry, Contributor  | | | Source:
Certificate Physical and Human Geography by Goh Cheng Leong. | |
For
the past few weeks, the focus of the lessons has been on the ecosystem. Some
of the things that we have learnt about the ecosystem are that it is "a community
of plant and animals within a particular physical environment", and it is
greatly influenced by climate, soil and human activity. The
topic of soil has already been discussed. I would now like to turn our attention
to specific climatic types as I continue the study on ecosystem. The equatorial,
tropical continental and tropical marine ecosystems are to be done. In reference
to the geography syllabus, we are required to know the following about these climatic
types: - Describe
the characteristics of the climate, vegetation and soil of equatorial, tropical
marine and tropical continental regions.
- Locate
areas where tropical rainforest and tropical grasslands can be found.
- Explain
the relationship between the climate, vegetation and soil of equatorial and tropical
continental regions.
How
much do you know about the equatorial ecosystems? Before you begin to respond
to this, I think I should ask - where can the equatorial ecosystems be found?
The equatorial climate is found between 5 degrees and 10 degrees north and south
of the equator. Its greatest extent and best examples occur in the lowlands of
the Amazon and Zaire basins as well as Malaysia and the East Indies. These areas
are indicated on the world map diagram. May
I encourage you to be familiar with these areas and also practise to outline them
on a blank map of the world. You can be tested on this in the examinations. In
the lesson on latosols, one of the major soil types studied, it was stated that
"latosols develop in humid tropical and equatorial latitudes as a result
of excessive leaching under heavy rainfall and continuous high temperatures."
This, in essence, has informed you about the characteristics of the equatorial
climate, the climate that is most important for the development of latosols. Let
us look in more detail at the temperature and precipitation of this climate. In
reference to the geography textbooks, the characteristics of the temperature for
this climate type are as follows: - It
has a mean monthly temperature of about 27 degrees Celsius (80 degrees F) with
very little variation.
- There
is great uniformity of temperature throughout the year.
- Cloudiness
and heavy precipitation help to moderate the daily temperature.
- The
diurnal range of temperature is small, between 6 degrees C (11 degrees F) and
8 degrees C (15 degrees F) and so is the annual range which is about 3 degree
C (5 degrees F).
The
characteristics of precipitation in the equatorial climate are as follows: - It
takes the form of rain fall between 1524ml and 2540ml (60 and 100 inches).
- It
is usually the convectional type often occurring in the afternoons and accompanied
by lightening and thunder. Mountainous regions also experience much orographic
or relief rain.
- The
rainfall is well distributed throughout the year as there is no month without
rain.
- There
are two periods of maximum rainfall in April and October which occur shortly after
the equinoxes.
- The
least rain falls at the June and December solstices.
- The
relative humidity is constantly high.
In
the next lesson, I will share information on the characteristics of the vegetation
of the equatorial ecosystem. As usual, I am encouraging you to do some reading
on the topic. The
responses to the questions given in the lesson last week are as follows: 1.
The major factor influencing the development of rendzians is the nature of the
parent material. 2.
The parent material, such as chalk and limestone, release large amounts of calcium
when they are weathered. This causes rendzians to be rich in calcium carbonate.
3. Rendzians
develop on the upland plateaus of Jamaica. 4.
Rendzians are dark in colour from the decayed plants mixed in with weathered limestone.
Marjorie
Henry teaches at Glenmiur High School. | 
