European Journal of Scientific Research - EuroJournals

416 N'guessan K. Edouard, Kouassi K. Edouard and Sangne Y. Charles
4. Discussions
The flora of the grid (400 ha) is rich of 463 species, in a fast inventory in 7 days working. KOUADIO
(1999) in Mopri and BAKAYOKO (1999) in Bossématié respectively obtained 162 and 308 vegetable
species during their study that take 6 months. Mopri forest covers a surface of 32 500 ha and that of
Bossématié extends on 22 200 ha. These 2 forests are located the same semi décidious field as that of
Téné Observing the results, the grid method presents better output than the surfaces methods of
KOUADIO (1999). It is the same in the association of surface and linear methods applied by
BAKAYOKO (1999). This good output is the consequence of the good site of the grid, witch is located
in several environments, where human actions are different. Like SOMÉ et al. (2002), the age landings
are replaced by the continuous, recent or old human action in the biotopes. Also it knows that, human
action an environment is synonymous of a floristic restructuring. By visiting several environments, we
increase our chances to meat several species. The method of the grid has the advantage of maximizing
the number of species in a short time.
The results obtained show that in a total way, species numbers (abundance) and diversities in
the biotopes are proportional (figure 5). But that are the accidental species which have an evolution
more similar to that of diversity.
The degree null of anthropisation is logically in the primary forest formations. The forest flora
of the grid is dominated by, Griffonia simplicifolia, Mansonia altissima, Motandra guineensis,
Nesogordonia will papaverifera, Sterculia rhinopetala, Marantochloa leucantha, Trachyphrymium
braunianum… A these constant species, we can add the other accidental ones for better characterizing
the forest vegetation of the grid. This species are Acridocarpus alternifolius, Baphia bancoensis,
Culcasia liberica, Musseanda elegans, Rinorea longicuspis and Xylopia acutiflora. The creation of
plantations brings destruction of the vegetation in place. It is replaced by another flora having diversity
lower than that of the primary forest (figure 7 and 8). In the 2 cycles define in the top, in the case of
Teak 2000 (figure 7) or in the food crops (figure 8), there is a fall of floristic diversity. In the 2 cases,
human action consists in a voluntarily elimination of useless species and favoured some others planted
species. This maintains of cultivated species, involves a fall of the number of species in general. The
cultivated taxa and the adventitious species, most resistant constitute the dominant new flora artificially
installation by men. The most abundance species of this new flora are Chromolaena odorata, Laportea
aestuans, Manihot esculenta, Croton hirtus, Euphorbia heterophylla, Mucuna pruriens, Parquetina
nigrescens, Theobroma cacao, Solanum erianthum, Centrosema pubescens, Tectona grandis and
Panicum maximum. Aside the cocoa-trees (Theobroma cacao) and Teak (Tectona grandis) which is
cultivated, the others taxa are the adventitious ones (AKOBUNDU and AGYOKWA, 1989). The few
residual forest species are found in the group of accidental and some times in the accessories. It’s a
matter of Deinbollia pinnata, Griffonia simplicifolia, cnestis ferrugenea, Dalbergiella welwitschii,
Baphia bancoensis, Mallotus oppositifolius, Sterculia rhinopetala…
After 3 or 4 years of maintains, the food crops become cocoa plantations. When Teak planted
into 2000 are replaced by the Teak reforestations 1994. We still attend a fall of diversity in the new
biotopes. This reduction is still made the weedings. For that it is necessary to add the effect of shade
creates by the increasingly significant foliages of the cocoa trees and the Teak. Under the seedlings
(Cocoa trees and Teak), the micro climate of shade will eliminate little by little the heliophilous species
from the preceding flora witch is dominated by the adventitious ones. The new flora is form by the
species of the crop plants, the certain adventitious ones and pioneer woody species: Theobroma cacao,
Tectona grandis, Chromolaena odorata, Nephrolepis biserrata, Cyathula prostrata, Panicum laxum,
Centrosema pubescens, Parquetina nigrescens, Pouzolzia guineensis, Millettia zechiana, Albizia zygia,
Clerodendrum buchholzii, Mondia whitei, Synedrela nodiflora, Deinbollia pinnata, antiaris toxicaria,
Blighia unijugata.
And then, when the Cocoa plantations of are abandon, they are transformed into Fallow. Some
years later, the fallow will transformed in secondary forests and cycle of manual action is finish. In the
cycle of mechanic action, the following environment are the multispecific reforestations composed of
the seedlings of Terminalia superba (Fraké) and Gmelina arborea (Gmelina). These multispecific