Botanist dedicates his life to improving greenery in Shanghai, Zhang Kun reports.

An aerial view of Chenshan Botanical Gardens in Shanghai. (GAO ERQIANG / CHINA DAILY)

Few people can claim to have played as big a role as Hu Yonghong in shaping Shanghai's green landscape. He was the key figure who helped to turn Chenshan Botanical Gardens into the largest of its kind in the country's east.

Located in the Songjiang district of Shanghai, the garden area was occupied by old residential compounds, rice-farming plots and a limestone cave before the local government in 2004 decided it would become a place to grow and study plants. Hu, then-general engineer and vice-general manager of the project, created a comprehensive plan for the garden's development over the coming decades.

Following his involvement in this project, Hu spent a year in Europe working as the personal assistant to the director of Kew Gardens in Britain, the most acclaimed botanical garden in the world and a UNESCO World Heritage Site. During his time in Europe, Hu had the opportunity to visit other institutions, and that made him wonder what a botanical garden in the 21st century would look like.

His answer: one with a global vision, aligned with national strategy and able to fulfill the needs of the public.

After returning to Shanghai in 2011, Hu was appointed executive director of Chenshan Botanical Gardens. One of his significant contributions was launching a project in 2017 to improve the soil－scientists had found that much of the initial soil was suppressing the development of new plants. According to Hu, the initial soil brought to the area consisted mostly of river silt and rubble, meaning it was fit for farming rice but not for the growing of trees.

What transpired was an engineering marvel. Within two years, the garden introduced a whopping 2 million cubic meters of fertile soil and adopted special measures to create a conducive environment for the growth of plants. The fruits of this labor made the headlines in the spring of 2020, with images of cherry blossoms in Chenshan splashed across new sites and social media.

Hu's ex-colleagues from Kew Gardens who visited Shanghai five years ago were astounded by the stunning transformation of Chenshan. "They told me that what we had achieved in five years would have taken them 50 or more years to complete," Hu says.

Today, Chenshan is a member of the international community of botanical gardens and has a collection of more than 15,000 species and varieties of plants from 71 countries and regions. Every year, about 1 million visitors flock to the garden area, which hosts seasonal blossom and harvest festivals and other events. The picturesque venue has also won several awards, including the 2020 National Award of Botanic Garden Excellence in memory of botanist Chen Fenghuai, and the Landscape Institute Award in 2018 for its Quarry Garden, which was reconstructed from a stone mine.

Children play with black swans at a pond in the garden. (GAO ERQIANG / CHINA DAILY)

Hands-on grower

Born in a farming family in Yanshi, a city in Luoyang, Henan province, Hu spent much of his growing-up years helping out in the fields. He recalls having to help with the summer wheat harvest even though he was preparing for his college entrance exam.

Given his background and seeing how the government was providing financial support to those who majored in forestry and agricultural studies, Hu chose to study at Northeast Forestry University in 1987. He sought to expand his knowledge further at Beijing Forestry University, where he graduated in 1997 with a doctorate, becoming one of the few botanic majors in China to hold a PhD at that time. He then joined the Shanghai municipal government to help make the city greener.

Over the past 24 years, Hu has helped to select and cultivate the plants seen today in Shanghai's public spaces and been involved in more than 50 national and municipal technological projects. Though he now works at Chenshan Botanical Gardens, Hu still plays an important role in the city's "green matters", among which are environmental conditions for trees.

He says many trees in the city used to be planted on sidewalks and sometimes near underground pipelines. Some trees were even planted above tunnels and underground parking lots, making it difficult for their roots to develop, and this created a potential hazard because such trees would easily topple during storms and pose a threat to the public. There was also the problem of bad soil quality.

In many parts of urban China, the soil is often mixed with stone, glass scraps and concrete blocks and tends to harden as vehicles pass over them. In Shanghai, the situation is especially severe because the soil also contains high amounts of salt and basification due to the high underground water level that is common in the Yangtze River Delta region.

To rectify such issues, Hu and his colleagues at Chensan Botanical Gardens worked together with a technical guidance center of the municipal landscaping administration and Morton Arboretum in the United States in 2018 to set up a joint lab that could design solutions.

The lab eventually developed a tailor-made soil system for Shanghai. The system includes two parts. The first consists of gravel that forms a framework that resists pressure from the ground above and prevents the soil from hardening. The second part revolves around soil filing, comprising organic fertilizer, biochar and soil conditioner that improves the biodiversity of the soil and ensures the healthy development of the root system. The lab also suggested adding a permeable layer of organic material such as shredded barks around trees and installing drainage tubes under the roots to absorb excessive rainwater.

This innovation has proved to be successful. Trees planted based on this system have been found to have branches that grow three times faster. This method of planting trees has since been applied to downtown areas of Shanghai. To commemorate this achievement, gum trees by the southern gate of Chenshan Botanical Gardens were planted in the same manner.

Hu has also been involved in the construction of Expo Culture Park in Shanghai, Xiongan New Area in Hebei province, and botanical gardens in Taiyuan, Shanxi province, and in Suzhou, Jiangsu province.

Hu Yonghong has a key role in developing Chenshan Botanical Gardens into the largest of its kind in the country's east. (GAO ERQIANG / CHINA DAILY)

Guarding ecosystem

To Hu, a botanical garden is more than just a beautiful environment. The study of plants that such a place undertakes is pivotal to the development of civilization, he says, adding that in the 21st century it also plays a critical role in preventing the extinction of species, improving biodiversity and addressing issues caused by urbanization, such as pollution and heat.

"The development of human civilization has been accompanied by the rapid degeneration of nature. A hundred years ago, one species would go extinct every two or three years. Today, we have several species disappearing every day," he says. "A botanical garden is a guardian of our ecosystem.

"We are like Noah's Ark, a place that rescues endangered species and breeds them before returning them back to nature."

In this vein, Chenshan has been experimenting on more than a dozen tree species, trying to find some that could be a good fit with Shanghai's urban landscape. Aside from the dominant species of local camphor trees and British "plane" trees that are prevalent in the former French concession area, Shanghai has in recent years also introduced a large number of Chinese gingko trees and southern magnolia, native to the US.

"We have found several species, such as tulips and gum, that are developing well in Chenshan and they can be planted in wider parts of Shanghai in the future," he says.

"I hope that with our continual efforts, Shanghai will become a city in an enormous garden, and become a fine example in the world for its ecological environment."

Despite having worked in this industry for decades, Hu is still fascinated by plants. When looking out of his office, he points to a tulip tree that was planted as part of an urban greenery project. That tree was the strongest among many others planted there.

"In 200 years, I would be long gone, but this tree could very well continue to grow. Just imagine what it would look like in 200 years," he says. "Sometimes I wonder if a tree acquires wisdom throughout such a long life."

Contact the writer at zhangkun@chinadaily.com.cn