Abstract: With Beian County as a model, an investigation shows that daring the period of last 70 years, the increase of population and the activity of unchecked production changed the stable natural ecosystem of the Great Northern Wilderness and formed an extremely unstable ecosystem with farmland as the main component. From now on, a harmonious development of agriculture, forestry and animal husbandry must be made.

Key words: Fish pond ecosystem, Bacteria, Energy flowing, Microbial food chain