Species diversity of Cochlospermum tinctorium A. Rich. vegetation of shrub savannas in northern Benin

Species diversity of Cochlospermum tinctorium community that occurs in dry savannas was studied in northern Benin. The objective of this study is to describe the community using the phytosociological method and to determine the variability of floristic composition of constitutive releves. The analysis of life form spectras had revealed the abundance and the dominance of annual species. The phytogeographical spectras allowed to establish the abundance and the dominance of the sudanian base-element. Species classification among higher phytosociological taxa showed that species that were most dominant were those of the Hyparrhenietea class of savannas and Soncho-Bidentetea pilosae class of fallows. The species diversity was higher at the community level than the constitutive releves. The herbaceous biomass of the Cochlospermum tinctorium community was 4.94 +/- 2.41 t DW/ha from wich the grass species biomass recorded was 3.84 +/- 1.44 t DW/ha. Statistical tests showed that the floristic homogeneity at the community level can include differences between some constitutive releves and then the phytosociological table can be seen as a synthesis of dissimilar and similar releves.