Abstract. This paper performs the qualitative analysis of a class of dynamic population models of commensal interaction of species competing for one substratum. The stability of all the stationary conditions is analyzed. All the special points are pointed out analytically and constraints are obtained for species growth characteristics and initial flows of the substratum and product. The qualitative changes in the dynamics due to variations of several system parameters are analyzed and bifurcational diagrams are plotted for all of the singular points. Figs: 4. Tabl.: 1. Refs: 8 titles.

Keywords: population models, commensalism, stability of stationary states, bifurcation analysis.