Abstract: Flagelliform nostoc (Nostoc commune) is a kind of algae, and grows in the arid and sem-i arid areas. In China, it mainly grows in five provinces including Inner Mongolia, Ningxia, Gansu, Qinghai and Xinjiang, and Inner Mongolia has the largest area and the most yield of flagelliform nostoc. During recent years, however, the trade quantity of flagelliform nostoc is rapidly increased, which leads to a large number of flagelliform nostoc gathering activities and results in a destructive disaster of the Inner Mongolia pasture. This paper evaluates the impact of the flagelliform nostic on the eco-environment of the Inner Mongolia pasture from the perspective of economics. It is estimated that the annual economic loss from the flagelliform is nostoc gathering about 10 billion yuan R MB, including that of livestock and animal products, burning consumption of bushes, extra expenses for the management of flagelliform nostoc gathering, grassland degeneration, etc. Moreover, the causes of the rapid increase of flagelliform nostoc gathering are analyzed. The results show that the increasing trade demand is an external cause resulting in the up-going of price of flagelliform nostoc, the increase of flagelliform nostoc gathering, and the degeneration of the flagelliform nostoc gathering, and the degeneration of the Inner Mongolia pasture, while the basic causes are the market control failure and the policy failure, which lead to an environmental cost externalization. Based on a consideration of how to deal with the contradictory relation between the flagelliform nostoc trade and the protection or eco-environment of the pasture, it is suggested to control the flagelliform nostoc trade, devote the major efferts to developing the artificial cultivation of flagelliform nostoc, and develop the substitute products of flagelliform nostoc by applying the economic means.

Key words: flagelliform nostoc trade, eco-environment of pasture, Inner Mongolia