The present study is based on the structural analysis of the diameters of the three species: Musanga cecropioides R.BR, (Parasolier), Prioria balsamifera (Vermoesen) Breteler (Tola) and Prioria oxyphylla (Harms) Breteler (Tchitola) Illegal settlements by people living on the Yoko Forest Reserve. P. balsamifera and P. oxyphylla do not have a good regeneration, M. secropioides to a trend towards a good generation but does not have individuals from class 9. The results show that M. cecropioides is declared non-vulnerable (94.5%) in Yoko while P. balsamifera and P. oxyphylla are said to be vulnerable. This is explained by the low vulnerability index obtained for these two species, ie 30.9% and 26.7%.