Overgrazing and unsustainable farming methods in northwestern China are turning once-fertile soils into dry lands.
This past summer, 10 young adventurers embarked on an 11-day expedition called Mighty Rovers to the Taklamakan desert in Xinjiang, the world's second-largest desert, to see conditions there first-hand. The trip was organised by Hong Kong Discovery to raise awareness of environmental issues among teens.
They camped for four days and three nights in the Taklamakan under the stars - without shower or bathroom facilities. They also visited Urumqi and neighbouring cities to meet researchers and local families.
The mainland has struggled to keep the deserts that already cover more than a quarter of the country from expanding further. Desertification happens when trees and plants that bind the soil and hold nutrients are cleared away for cultivation or stripped bare by livestock. This puts water supplies and food at risk. Scientists at the Taklamakan Desert Research Institute are trying to prevent that from happening.
Natalie Lau Sin-ying, a student from Maryknoll Convent School who went on the trip, saw a strategy at work along highways and villages: grids of straw squares, each of which measured about one square metre. "The straw grids look like massive fishnets over the sand," Natalie says. "They can hold the ground together and stabilise soil."
Scientists are also studying whether planting poplar, red willow, or saxaul trees - the "three desert treasures" - can stem the tides of sand.
"I used to think deserts were too arid for any plants except cactus," says fellow traveller Michelle Sze Wing-sum, who attends Canossa College. "Scientists found there are many different types of plants that could endure deserts' harsh conditions."
Researchers are studying changes in wind directions, seasons, water sources and sand quality to make their grids work better.
Needless to say, it's not easy to live in a desert, where it can become as hot as 45 degrees Celsius by day. The visiting students found that there was only one water storage tank every five kilometres on the highway. A fixed amount was trucked to the research grounds weekly.
When natural resources are scarce, Michelle notes, scientists must carefully allocate the limited water they have to different uses such as tree-planting experiments, cooking, drinking and cleaning. "We shouldn't waste water," she says.
"Every drop is precious. We are not short of water in Hong Kong, but we should do the same."
Before they entered the desert, the students visited a market at Korla to stock up on essential supplies such as bread, vegetables and meat. An unexpected encounter taught them another lesson about the need to value resources.
"We ordered a goat and saw the animal slaughtered before our eyes," says Natalie, who had only bought packaged meat from the supermarkets before. "The animal's throat was slit, it was struggling and bleeding badly. We were very scared. This experience told me I have to finish all my food and not let animals die for nothing."
The group also visited the Glacier No 1 in Tian Shan Mountains.
Michelle said the glacier was not all covered in snow as they'd expected. Instead, it was a cluster of rocky mountains with snow-capped peaks. "Villagers told us ice has retreated 3km in 30 years," she says. "The impact of global warming is obvious."
Natalie Lau tries out local food in the desert camp.