Marcel R. B. HOUINATO (2001). Phytosociology, ecology, production and carrying capacity of rangelands surrounding Monts Kouffé (Benin). Free University of Brussels, Belgium. 264 pages.
Promotor: Prof. Jean LEJOLY.
Abstract: Between 1996 and 1998, floristical surveys were carried out. Some 159 phytosociological relevés were done, according to Braun-Blanquet approach. They resulted in 954 herbarium specimens corresponding to 584 species. Detrended correspondence analysis of these relevés leads to nine well defined new plant associations which were classified into two classes. Hyparrhenietea class Schmitz 1963 of the sudano-zambezian savannah communities enclose the Schizachyrio-Sorghastretum bipennati ass. nov. of swamp on clayey soils, the Loudetiopsio-Hyparrhenietum rufae ass. nov. of swamp on sandy soils, the Elymandro- Monocymbietum ceresiiformi ass. nov. of fallows wetland, the Gardenio-Siphonochiletum ethiopici ass. nov. of savannas in evolution and the Gardenio-Pteleopsietum suberosae ass. nov. of fallows on plateaus. The Erythrophleetea africani Schmitz 1963, class of woodlands enclose the Andropogono-Isoberlinetum dokae ass. nov. of young woodlands, the Uapaco-Isoberlinietum dokae ass. nov. of more evoluted woodlands, the Aframomo-Anogeissetum leiocarpi ass. nov. and the Pouterio-Anogeissetum leiocarp iass. nov. of dry forests. The maximum phytomass significanty varied among associations during the same vegetation cycle. The highest maximum phytomass was obtained in swamp savannah and the lowest in woodlands. Considering life forms that composed the associations, phanerophytes (36%) and Therophytes have highest proportion. About phytogeography, Sudanian species represent 16.1 % of the total flora spectrum of Mounts Kouffé region. Two species of the three endemic genuses to sudanian region were collected, i.e. Vitellaria paradoxa and Pseudocedrela kotschyi. The species present in both Sudanian and Zambesian regions made up 13.5% of the phytogeographical spectrum and those of the Guineo-Congolian region accounted for 11.3% of the spectrum. They mostly belonged to gallery forests and dry forests because of the position of this region which is located in the most southern part of the Sudanian region close to the regional transition zone of Guinea-Congolian/Sudanian. The other species widespread in several regions within continental African phytochoria represented 33% of the spectrum. Widely distributed species represented 25.2% of the spectrum. The impact of bush fire on the dynamic of vegetation in Bassila forest was studied. The results show reforestation in the plot protected from bush fire and decrease of forest species in the plot affected by late fire. In the plot affected by early fire, most species present at the beginning of the study had a normal development. Late fire allowed apparition of new species of therophyte (36%) and decrease of phanerophyte species. Phanerophytes have the same values (45 %) in the plots protected from bush fire and those affected by early fire.