Abstract: A mechanism model simulated density dynamics of the zooplankton population in Dapeng Bay was described. The data were based on the samples taken 2 days intervals from April 2 to June 22,1990. The factors including phytoplankton, temperature, salinity, dissolved oxygen(DO), pH,dissolved inorganic phos phate(DIP), dissolved inorganic nitrogen(DIN) (NO₂_N, NO₃_N), Si(OH)₄, Fe and Mn were measured. It was identified that phytoplankton and temperature were the controlling parameters on the growth of zooplankton. By using hierachy to the reciprocation and introducing into the model identification, three non_linear regression models were established.

Key words: mountainous area of southern Ningxia, typical plant, rhizosphere soil, soil carbon, soil nitrogen.