differ in an average lower height and in a scanty density. It
shows a pale-grey tone, a coarse texture and an irregular structu
re owing to the presence of some big plants spaced by numerous
smaller other plants.
- Swamp grassland: this type of vegetation appears in zones sub-
ject to very frequent overflows and where water often stagnates
for long periods of time. It is formed by a grassy vegetation
having a regular height of about 35/40 cm. and without continuity.
The tone is very pale-grey, the texture thick and the look very
homogeneous.
Secondary growth:
It is present in lands where the original vegetation has
been cut since a short time, and is formed by very young plants
lower than 2 mt. The tone is easily distinguishable from the sur-
rounding vegetation for the different height.
Cultivations:
Limited lands mainly cultivated with maize, manioc, rice and
kapok. They are easily distinguishable for the geometric arrange-
ment of the fields. A
Second phase: Campaign surveys and division into topographic and
morphologic sections by means of photo-plotting.
The campaign surveys were mainly carried out along signifi-
cant sections previously defined on the basis of the maps drawn-
up during the first phase and of the practicability and accessibi
lity ascertained through the air photograph interpretation.
Along said sections were executed traverses and field checks,
which, besides to verify what found with the interpretation of air
photographs, permitted also to supply more precise information
about the type of vegetation, the physiographic course, the drai-
nage characteristics and soil type. During each survey along each
section, the most possibly uniform data were collected, thanks
also to the use of a form conveniently prepared. In order to point
out the morphology of the examined area in details, and not only
through an aerial but flat representation as is the land-units
map, but also through a tridimensional vision, which supplies a
real representation of the relief, it was deemed advisable to
realize two representative topographic sections.
No reliable and comparable topographic data were available,
due to the difficult accessibility to the zones and the consequent
scantily knowledge; a certain trustworthiness had only the heights
along the riversides Segah and Kelai, respectively 7 and 16 meters
above the sea level, with a difference in height comprised between
9 and 10 meters, between the two rivers, in the examined zone.
It resulted therefore that the sections, besides crossing
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