Environmental Engineering Reference
In-Depth Information
The rather high rank of
V. paradoxa
in Ghana could be due to the fact that the
species has economic value for the production of shea butter for commercial
purposes, and is therefore left protected in place so that its fruits may be harvested
for sale.
The absence of pole-size classes of the different woody species encountered in
the sample plots at Kouroussa-Moussaya may be due to the use of fire in the
early-burning vegetation management practice.
Abundance diversity and Shannon-Wiener index
The observed small numbers of a large number of species in the plots studied in
both countries are characteristic of the natural heterogeneous ecosystem globally.
However, the observed abundance diversity of
D. oliveri
in Guinea, which is three
times higher than in Ghana (0.34 and 0.11, respectively), can be attributed to the
protection of the study area as a reserve in Guinea. In the same way, the several-
fold higher abundance diversity for
V. paradoxa
in the plots in Ghana can be
attributed to the protection accorded to this species due to its economic value for
shea butter production as noted above. The observed similarity in the values of
abundance diversity of
P. clappertoniana
for Guinea and Ghana may be due to the
similarity of protection of the species as an important food condiment.
Girth, height-class distribution, and utility
The observed high representation of individuals of each of the larger girth
(200-250 cm) and height classes (20-25 m) in the plots in Guinea appears to be
related to the type of management practice, which, in Guinea, involves the pro-
tection of the study area as a reserve, unlike in Ghana where no such protection
occurs. Consequently, the high demand for woody species to supply household
energy requirements either as fuelwood or charcoal has led to the denuded state
of the vegetation in the study areas in Ghana.
Aside from use as fuelwood, most of the species encountered in the plots stud-
ied in the two countries have value as medicine, dyestuff, or food colour, besides
being commercial sources of edible fruits.
While fencing of the household was not a common feature of the settlements in
the vicinity of the plots studied in Ghana, it was a major feature in such settlements
in Guinea.
In Ghana, the high population density and a concomitant high demand for fuel-
wood and charcoal as a domestic energy source may be contributing to defor-
estation and adverse changes in the microclimate.
It is arguable that the savanna woodland can turn into forest when protected (Eyre,
1968; Bourlière and Hadley, 1983). However, vast areas of this woodland, particu-
larly in the case of Ghana, are becoming thinned and impoverished as a consequence
