The picturesque North Mountain Forest Park in Xining is a popular destination for both tourists and locals, with white clouds rolling endlessly over the green and high mountains, twittering birds and fragrant flowers dotted in the thick forests that spread around the grassy slopes. A river, gurgling from the uplands, runs along pavilions and bridges, then into a deep blue lake in the distance.

The scene may be common on the plains in southern China, but the setting is in fact the capital of Qinghai province, the largest city on the arid and freezing Qinghai-Tibet Plateau. The city has gone through a sea change over two decades, as its green coverage ratio surged from 7.2 percent in 1989 to 75 percent today.

The dramatic transformation of the North Mountain Forest Park in Xining, capital of Qinghai province, from 2013 (above) to Sept. 5, 2017. [Photo courtesy of Xining Forestry Administration]

"Once, the mountains were all yellow; now, you see that they are green," Wang Zhi said as he gazed into the sea of trees. The director of the Xining Forestry Administration has had a front-row seat to the city's dramatic green transformations, right from when Xining launched its afforestation campaign in the north and south mountains in 1989.

"People in Xining rely on the weather for their livelihoods," Wang said that frequent sandstorms, brought by severe wind and soil erosion in the mountains, severely impacted the residents' quality of life and social-economic development. The pollution and depletion of the nearby Huangshui River beginning in the early 1990s caused further environmental degradation.

Thus, planting trees, as one of the best ways to preserve water and soil, has been high on the agenda of the government's plans. Wang said the government invested 13.5 million yuan (US$1.98 million) on the afforestation campaign of the two mountains in 1989 — a large sum for an environmental project at a time when many provinces in the country were focusing on trade.

However, planting trees in the mountains, where the annual rainfall is 32 centimeters while the annual evaporation rate reaches as high as 130 centimeters, is a tricky proposition.

"Here, planting a tree is harder than raising a child," said Wei Minlao, a 62-year-old veteran tree planter who has worked almost 20 years in the north mountain.

In March 2014, Xining sets a requirement that the area of green landscape in the North Mountain Forest Park must remain at a minimum of 400 hectares. [Photo courtesy of Xining Forestry Administration]

Wei recounted the early days when he arrived in the mountains. "It was mid-April, but deep in the mountains winter was still battling for its last strong hold. We put on everything available, from cotton-padded overcoats to leg wraps. Ice formed on our clothes, turning them into hardened armor under which we sweated," he said. "Many of us, me included, developed severe rheumatism as a result."

Despite the harsh working environment, what worried Wei most was the lack of water in the soil. "Water shortage was one of the biggest problems. The steep hills and stony soil, which cover nearly 90 percent of the mountains, could not provide enough water and nutrition for trees to grow."

To tackle the problem, Wei dug square holes about 20 centimeters deep, filled them with fertile soil, planted a sapling in each hole and used drip irrigation. "The soil was so precious that we put it in our cupped hands and poured it carefully into the hole, not wanting to waste even a pinch."

Wei said that no one believed this would work at first, but he eventually proved them wrong. "I always told my colleagues to treat these trees as their children. You must carefully treat them, and then they can grow fast and well into a forest."

Saplings on the mountains around Xining are planted in 60 by 60 centimeter square holes at a depth of about 20 centimeters. [Photo courtesy of Xining Forestry Administration]

Once the trees are planted, another challenge was protecting them against the harsh conditions at high altitudes on the Qinghai-Tibetan Plateau. Wang said the Xining Forestry Administration developed many new techniques to keep the trees alive and improve the ecosystem around the city. "To plant a tree in the mountain requires skill, and to preserve it for a long term is art."

Xining invited experts to study the local climate and soil conditions, and according to the findings introduced around 20 suitable plant varieties, all of which are resistant to wind, drought and cold. To improve the irrigation system, the city built 62 pump stations and 570 reservoirs for drip irrigation, with pipelines spanning 2,000 kilometers around the mountains.

In addition, Xining made it a priority to manage water resources and combat water pollution. It appointed 953 water chiefs at various levels to monitor the nearby Huangshui River and the surrounding areas. Its 11 urban sewage plants had a combined daily capacity of 375,000 tons, treating 91.5 percent of urban sewage in 2017, according to data from the Xining Water Authority.

The city recently finished building a large wetland park next to the Huangshui River, and it is expected to open to the public in October. "The park's highland ecosystem comprising rivers and meadows is of high scientific value," Tao Yaqin, the park's director, said.

The Huanghsui River Wetland Park in Xining, capital of western China's Qinghai province, is expected to open to the public in October. [Photo courtesy of Xining Forestry Administration]

As an old Chinese saying goes, "One generation plant the trees in whose shade another generation rests." According to the Xining municipal government, 25,333 hectares of the afforested area planted with at least 50 million nursery stocks as of 2017 could decrease the sediment by around 75,000 tons per year, greatly reducing water and soil loss. Compared to years before, local precipitation has increased by 50 millimeters, and its micro-climate has been improved, experts said.

The afforestation project in the Xiaoyoushan Mountain in Xining, capital of western China's Qinghai province, sets a successful example for planting trees at high altitudes and in a cold desert region. [Photo courtesy of Xining Forestry Administration]

A combination photo shows wastewater (left) after treatment in the urban sewage plants is ready for daily use. [Photo by Wu Xiaoshan/China SCIO]

"The government and citizens have all participated in the project to build Xining into a green city," said Liu Bo, director of Xining's Green Development Committee. "We believe it is the right thing and the right time to turn the wasteland green, and to let more people benefit from the city's green development."