While the blue sheep on the Helan Mountain range in northwest China are enjoying an expanding kingdom, Chinese experts are concerned over a possible ecological imbalance in the area.
The population of blue sheep, once cited as endangered and under state-level protection in China, has jumped from 1,585 in 1983 to the current estimated maximum of up to 10,000 in the Helan Mountain Range Nature Preserve in northwestern Ningxia Hui Autonomous Region.
Liu Chuguang, a researcher with the provincial institute of zoology in Shaanxi, a province neighboring Ningxia, said yesterday that the living space of the blue sheep population in the preserve has been turning smaller and might eventually lead to ecological problems in the area.
Blue sheep usually haunt bare rock areas above an altitude of 2,400 meters, but the animals in the preserve sometimes now descend to river valleys as low as 900 meters in altitude, Liu noted.
Now the dwelling area of the animal covers approximately 850 square kilometers, or 62 percent, of the total area of the preserve.
In the past blue sheep could occasionally be seen only among cliffs and precipices, staff at the wild life sanctuary said, but now they can often be found wandering on roads in the morning or before sunset.
The animals even intrude into local farmers' fields nearby and nibble their crops, fuelling demand for compensation from farmers, staff said.
The increase of the blue sheep population has so far caused a deterioration of grassland in the preserve, Liu said, and when the animals find that their former food resources can no longer satisfy their demand, they will look for them in other places.
This could cause a wider deterioration of vegetation in the preserve, Liu warned.
The zoologist, who has been following the phenomenon for three years, said that the population of the sheep will reach the maximum of the preserve's accommodation ability by 2005 if it continues to grow at the current rate.
It's likely that when the blue sheep population hits a ceiling, the vegetation in the sanctuary will be over-exploited, resulting in a worsening of local vegetation, he said.
A further danger as a result of the deteriorating vegetation, Liu added, would be the possible downgrade of the mountain range's function as a natural barrier against wind and sand for the adjacent plain.
While the sheep is a powerfully reproductive animal, it has almost no natural foes in the preserve except eagles and foxes, which Liu said pose a threat to newborn lambs only.
(Xinhua News Agency April 23, 2003)
