Food-chain model of grassland degradation and its restoration process in northern Tibet Plateau: A case study in Nierong County

Based on the model of grassland climate ecological productivity, the process of grassland degradation and its restoration mechanism in northern Tibetan Plateau were discussed by the model of food-chain in which the environmental and human factors were corrected. The results of case study in Nierong County showed that: ① the climate trend of becoming warmer, more droughts and gales were conflicted with the restoration of grassland degradation, even under level of perfect management the climate ecological productivity was declined from 89.3 kg/m 2 of 1983 to 71.8 kg/m 2 of 2003; ② from 1983 to 2003, the population increased fast, while the variation of livestock on hand was little, and the cost of its maintaining is rapid grassland degradation; ③ on the present condition of overgrazing, the livestock on hand can be maintained on the level of theoretical carrying capacity in 2033 by applying the mechanism of food-chain in grassland ecological system controlled with expected coefficients, so that to realize the policy of determining the quantity of livestock according to grass growth.