LANZHOU, Sept. 18 (Xinhua) -- Zhai Shuang'er rises early each day to visit his old friends -- the ancient and rare trees in the downtown area of Tianshui, a city in northwest China's Gansu Province.

He observes the growth of each tree by touching its trunk and checking the growth of the leaves, jotting the details in a notebook.

"The ancient trees are like living fossils of a city, recording the changes in the city and carrying people's nostalgia for the past. They deserve meticulous care," he said.

Sixty-year-old Zhai is a landscape engineer with a Tianshui-based engineering company focused on greening. He has been engaged in landscaping and restoring ancient trees for more than three decades.

Dating back over 2,700 years, Tianshui is home to more than 2,900 ancient and precious trees. Of the total, more than 100 are over 1,000 years old, according to statistics released by the Tianshui forestry and grassland bureau in 2019.

As a native of the city, Zhai said his childhood memories are closely related to ancient trees.

"There was an elm tree that was around 500 years old in the alley where I grew up. The hollow crown of the tree made it a paradise for me and my friends to play hide-and-seek in," he recalled.

However, due to lack of effective protection measures, many ancient trees suffered from pests and plant diseases, natural disasters, pollution, and human behaviors, including graffiti.

To solve these problems, in 2019, Tianshui approved a set of regulations on the protection of the city's ancient and famous trees. Meanwhile, the city initiated a survey to collect information on the trees, including their species, distribution and growth conditions, feeding it into a new database.

"During the survey, we found that many trees were in urgent need of rescue and protection," said Fu Jianhong, director of the municipal historical and cultural city protection center.

The center organized experts to come up with protection measures for the trees based on their respective problems, including treating tree holes, as well as installing fences and trunk-supporting structures, to improve their living environment.

The elm tree that Zhai knew in his youth was a beneficiary of the protection. Botanists and experts cleaned up its hollow crown and filled the various holes to help it revive. Their work bore fruit, with tree branches and tender leaves growing, and new flowers coming into bloom.

However, the protection work has not been without its difficulties.

"It's hard to create enough space for ancient trees, as many of them grow in the crowded downtown area," said Fu.

In 2021, experts found a honey locust tree in a residential area. The tree had struggled to survive, suffering malnutrition due to an adjoining cement road that prevented its roots from growing properly.

To save the over-300-year-old tree, the cement road had to be replaced with something less harmful.

In the beginning, many residents found it hard to understand why a newly-paved road should be dug up for the sake of a tree, said Fu. He and his colleagues paid multiple visits to the residents to persuade them.

Finally, with the residents' support, they dismantled the cement around the tree, replacing it with ventilated lawn bricks.

"Now the tree is regaining vitality. During summer, the tree provides shade and coolness for the residents. People finally understand the true meaning of harmony between man and nature," Fu said.

According to Fu, Tianshui has spent more than 4 million yuan (about 577,160 U.S. dollars) on rescuing and rejuvenating more than 200 ancient and precious trees.

Meanwhile, the city has strengthened tree protection through more advanced technological means. ID cards with QR codes have been created for each ancient tree and probes have been installed to monitor the growth of several significant trees.

For Zhai, the regular rescuing and rejuvenating efforts not only provide protection for ancient trees. "More importantly, it makes people realize the ecological significance of protecting them," he said.