The grassland ecosystem in the Qinghai-Tibet Plateau has shown a gradual-deterioration trend with its output decreased sharply due to long-term excessive herding.

The throughput of the grassland dropped from 4,500 kilograms in 1960s to the current 1,500 kilograms per hectare while the amount of field mice rose from 8-10 per hectare to over 30, said Du Guoqin, professor of Lanzhou University.

The naked land is spreading over 30 percent of the total area with the rest covered with more poisonous weed, Du said.

The Qinghai-Tibet Plateau has been one of China's important pasturing areas from of old for its ample grassland resource, forming a particular ecosystem, which covers the largest area and at the highest water level in the world.

The plateau is also the birthplace of the Yangtze and Yellow rivers. Its ecological situation can directly affect the fundamental interests, even the existence and development, of the Chinese nation, according to Du.

He said the deteriorating condition of the ecosystem has caused large amount of livestock to die.