Abstract: Based on sexual reproduction and birth matrix-mating rule model (BMMR model), the following representatives of birth and death rates of sexual population were obtained: (dN/dt)_b=N²g_b(N)=bN²(1-uN+w₁N²),(dN/dt)_d=Ng_d(N)=dN(1+vN+w₂N²). Tus predator-prey system can present limit cycles with cusp geometry. The sexual population has humped curves of natural increase rate of individuals as function of population size and two equilibrium points: stable Sand unstable X, S>X, an asexual population can only have one equilibrium point, i.e. stable S.

Key words: Pinus densiflora var. zhangwuensis, Pinus sylvestris var. mongolica, salt-alkali stress, physiological indices.