The words of a popular Vietnamese song about Hanoi celebrates the city's tree-lined streets in autumn – "bright yellow celtis, tropical almonds with red leaves standing next to each other; old streets and ancient houses with brown tiled roofs."

Written by late composer Trinh Cong Son, one of the most popular song writers of the 20th century, Nho mua thu Hanoi (Missing

Hanoi in Autumn) has for decades provided an iconic image of the capital.

The words have been imprinted on the minds of every true Hanoian – and those who have visited or long to see the city.

The presence of old trees shading and colouring the capital's streets has inspired dozens of songs about Hanoi .

However, the lack of a master plan for the protection of road-side trees and poor management methods continue to threaten the very fabric of the city.

Nguyen Duc Manh, from State-owned Hanoi Park and Tree Company's Planning and Technique Department, says no specific research has been conducted on street trees, although they make up a major part of the city's green areas.

Associate Professor Dam Thu Trang, dean of the Civil Engineering University's Landscape Architecture Faculty, says tree numbers and locations are recorded in a haphazard way and that "digital technology should have been in place by now."

More than 44,000 trees, belonging to 70 species, shade hundreds of roads and streets in central Hanoi . Many of them are more than a century old.

Andreas Jarfe, an arborist from Germany , says he is amazed by the greenery in Hanoi .

"Street trees in Hanoi are beautiful, old, unique. I know all the names of the trees in Germany but not many here," Jarfe says.

Duong Duc Tien, a biology professor, says many of the city's trees, often overlooked by Hanoians, are rare and valuable.

Despite the continual loss of trees due to urbanisation, their number has risen gradually year by year, says Manh, adding that there were about 42,000 in Hanoi 's nine districts ten years ago.

On average, the city plants between 1,500 and 2,000 new trees a year, and spends about 4 billion VND (210,000 USD) annually maintaining them, Manh says.

To boost survival rates, the municipal People's Committee on July 1 raised the special care period for newly planted trees from two to five years.

Meanwhile, mature and established trees are inspected and pruned monthly or quarterly depending on their condition.

Trang says the effort expended by city officials and the Hanoi Park and Tree Company to maintain Hanoi 's trees is "tremendous".

Despite urbanisation, Pham Van Khanh, deputy director of Hanoi 's Natural Resources and Environment Department, says every effort is made to keep the city green. "Wherever possible, new trees are planted along the city's streets," Khanh says.

However, despite the valiant efforts of the authorities, street trees struggle to survive in the modern age.

"Trees in Hanoi face far greater problems than their cousins in developed parts of the world," Trang says. This is because of the ever-expanding underground infrastructure of the streets, which limits the choice of trees and makes planting difficult.

"I can see Hanoi has a similar problem to Germany but more severe – the trees are struggling because of the shortage of space for root development," Jarfe says.

The narrowness of the many short streets and inadequate coordination among different sectors have also proved a challenge, according to Trang.

The landscape architect said Hanoi 's streets were traditionally lined with one or two species of tree. Now, she said, trees are planted almost haphazardly and are rarely in keeping with the local architecture.

According to a Park and Tree Company report, typically 7 to 15 different tree species now line each of Hanoi 's street, and in some places 18, instead of one or two only to make the street unique as it used to be.

Renowned lyricist Hoang Hiep used to walk along Nguyen Du Street hand-in-hand with his girlfriend. While away from his beloved part of the city, he penned: "Nights full of the fragrance of pulai [sinensix] tree blossom," for the song Nho ve Hanoi (Thinking of Hanoi).

Similarly, Lo Duc street was renowned for its tall dark-trunked thingan trees (hopea odorata), Ly Thuong Kiet street for its flamboyant, Phan Dinh Phung, Le Thanh Tong and Tran Hung Dao streets for their sau trees (dracontomelum), Tran Nhan Tong street for styrax, and Ton Duc Thang Street for African Mahogany (khaya senegalensis).

Despite their love for Vietnam , Trang and Tien admit that Hanoi owes much of its beauty to the efforts of the French a century ago.

Tree planting nowadays is in its infancy, and landscape design leaves much to be desired, Tien says.

Maintaining a city's arboreal integrity comes at a price – each tree planted in a German city costs about 1,000 USD and takes between 15 to 20 years to mature, Jarfe says.

Although costs are lower in Vietnam and rainfall more plentiful, maintaining Hanoi 's 40,000 trees is no mean feat.

"The Park and Tree company has dozens of workers, but they cannot cope," Tien says, adding that the best solution would be for the State to join hands with the public.

It is a view supported by Nguyen Thi Ngan Giang, who lives on Quan Thanh street .

"Green trees have always been part of my street and my life. I would be delighted to help protect them," she says.

Trang says the State should hand over the trees it has planted to local residents, who would then be responsible for their upkeep.

"If the trees belonged to the residents they would do their best to protect them," she says.

Tien believes if that stratagy is adopted, residents would be less likely to nail signs to tree trunks, dump rubbish nearby, or hack away at inconvenient branches.

Whatever city leaders decide to do, Tien hopes with all his heart that urbanisation does not come at the expense of Hanoi 's colourful heritage./.