Abstract: Keerqinzuoyihouqi is located in agriculture-grazing ecotone in northeast Keerqin lands. On account of the complex and fragile environment, it is important to harmonize the relationship among population, resources and environment. Land sources capacity became important in settling the problem. In this paper, a dynamic model was established, including population, land resource, planting, husbandry, fishery and consumption subsystems. Across 9 scenario, i.e.,3 development rate ^* 3 nutrition level , the model predicts changes of population and maximum land resource capacity in the future 50 years. The actual population increase and ecological environments were further discussed. The results showed that the land capacity for population ranges from 467,100 to 745,100 and the intervals to maximum capacity are different among different scenarios. So population control is necessary for economic development and environment protection. In fact the population inscrease rate is rational. The environment questions is caused by irrational development.

Key words: 3S techniques, Ecological landscape planning, Principal analysis, Digital elevation model