Étude de la diversité floristique des ptéridophytes à Brazzaville, Congo

study of the floristic diversity of pteridophytes is carried out in the urban forest ecosystem of Brazzaville which is very damaged by anthropogenic actions and whose flora, in particular the pteridophytes are poorly known. The itinerant floristic inventory results in 24 species representing 19 genera and 11 families with 83.33 % of the taxa Polypodiaceae. From the listed taxa, Pteris vittata already known elsewhere has been recently identified in the Congo. In relation to habitat type, epiphytic are predominant with 6 species in 2 Polypodiaceae families (83.3 %) and Davalliaceae (16.7 %). The wetland flora has 5 species grouped in four families as follows : Adiantaceae (20 %), Athyriaceae (40 %), Schizaeaceae (20 %), Blechnaceae (20 %). Terrestrial pteridophytes Group 3 species, with a predominance of Dennstaedtiaceae (66.66 %). This distribution shows two groups : (i) a group of species known as ecological bio-indicators Perfect, specialized in a well-defined biotope and meeting specific ecological requirements ; (ii) The second is made up of taxa (non-bio-indicators) that are almost indifferent to environmental conditions. In view of the adaptations developed, the diversity and specificity of the occupied Biotopes, and the bio-ecological services recognized in the pteridophytes, they are nevertheless a good teaching material and/or support of the teachings of the sciences of the Life. Phytogeographic analysis reveals that the large-distribution element dominates (75 % of taxa) dominates the endemic element (25 %). The development of the public urban roads in general and the degradation of the urban forest ecosystem, as a result of recurrent anthropogenic actions and higher levels of intensity, strongly impact the growth of pteridophytes populations in the city of Brazzaville