At the same time, from many years of practice, farmers consider burnt grass ash to be a good fertilizer for crops, so they set fire to vegetation on slopes in late autumn and let the ash be washed down onto the farmland.

"However, such fires often get out of control, not only burning shrubs and grasses, but also killing mosses and algae on rock surfaces under the high temperatures generated," Yuan said. Algae and mosses are pioneer plants for karst forest, so loss of them will make the recovery of vegetation even more difficult.

Besides, in some urbanized or industrial areas, air pollution and acid rain have a similar effect in killing pioneer species. In extreme cases, carbonate rock surfaces over broad areas are bleached white following the death of algae and lichen. "Studies show that such terribly degraded landscapes will not recover even in 20 years after the responsible damaging factors are removed," Yuan said.

Direct results of stony desertification are water shortage, soil erosion and persistent poverty since few crops can survive in such thin and arid soil. According to SFA statistics, of the total 592 national-level poverty-stricken counties, 227 are located in stony desert areas, with more than 50 million people living below poverty line.

In Guangxi, more than 90 percent of its poverty-stricken people are living in stony desert areas, according to the regional forestry department.

"Since stony desertification has dragged so many people into poverty, the work to control stony desertification should be integrated with efforts to improve local people's livelihoods," said Wang Guoliang, Deputy Director of the State Council Leading Group Office of Poverty Alleviation and Development.

Curing the illness

In 2008, the State Council, China's cabinet, approved a plan to control stony desertification in karst regions in the country's south and southwest. The plan called for greater investment in environmental improvement in the karst regions and special allocations to deal with desertification in eight priority provincial-level regions. One hundred counties in Guizhou, Yunnan and Guangxi were included in the plan.

The campaign to control stony desertification will be extended to 200 counties throughout the country by the end of 2015. Its goal is to turn another 4 million hectares of stony deserts into forests, said Du Ying, Vice Minister of the National Development and Reform Commission.

After years of fighting stony desertification, land conditions have greatly improved.

Reforestation and vegetation protection, the adjustment of rural energy structure and the application of modern agricultural technologies contribute a lot to ecological restoration in stony desert areas.

Local governments also encouraged farmers to grow cash crops on stony lands to improve vegetation and increase earnings. A new breed of goat, meanwhile, was also imported from Australia to stony desertification-affected provinces. They feed on grass but leave the roots untouched.

"Intensive agriculture has been promoted in those areas to improve farming yields. The application of modern agricultural technologies are significant to the ecological restoration in those affected regions," said Liu Tuo, Director of the Desertification Control Center under the SFA.

In Guizhou, 169 villages have benefited from a land revitalization project. About 40,000 hectares of grassland has emerged from bare rocky lands and now support 420,000 goats, which has helped to increase the per-capita income in these areas from 630 yuan ($98.98) in 2001 to 5,900 yuan ($926.94) last year, according to official statistics.

However, Zhang also warned that the country still faces severe challenges in fighting stony desertification, as activities including overgrazing and destroying forest for land reclamation still exist in some poor rural regions.

"Frequent natural disasters such as droughts and freezing weather have also posed difficulties in combating stony desertification," Zhang said.

For instance, with successive years of drought, stony desert areas now spread at an annual rate of 6.8 percent in Qujing City, Yunnan Province.

Stony desert areas now threaten the headwater areas of the country's major waterways, including the Pearl River, major tributaries of the Yangtze River, as well as water sources of the South-to-North Water Diversion Project and the Three Gorges reservoir, according to the SFA.

"The stony desert areas with water loss and soil erosion cause sand deposits in the lower reaches of the rivers, which pose great threats to the local environment, as well as to lives and assets along the rivers," he said.

Li Maosong, a researcher on disaster reduction at the Chinese Academy of Agricultural Sciences, suggests governments at all levels continue to increase investment in local environmental improvement and give more subsidies to farmers to encourage them to abandon destructive farming practices that may aggravate stony desertification.

"A long-term mechanism should be established to supervise the recovery of the vegetation, in a bid to stop the degradation backlash in handling stony deserts," said Zhong Shiquan, Deputy Director of Guangxi Meteorological and Disaster Research Institute.

Email us at: yinpumin@bjreview.com