x Abu Dhabi, UAEWednesday 26 July 2017

Transplants give a life-saving lift to Abu Dhabi’s oldest trees

Some of the oldest trees in Abu Dhabi are being preserved as part of the redevelopment of Mushrif Central Park. These elder statesmen contribute far more to cities than previously thought – such as energy savings, w

Bigger trees need larger containers to maximise their survival chances after being replanted. Sammy Dallal / The National
Bigger trees need larger containers to maximise their survival chances after being replanted. Sammy Dallal / The National

ABU DHABI // They are some of the city’s oldest inhabitants, a race of giants whose roots literally go deep into the city. Now they are safe for future generations to enjoy.

In developing the new Mushrif Central Park, exceptional measures are being taken to preserve the trees that have long stood on the site.

“These may be some of the oldest trees in Abu Dhabi,” explains Abdul Aziz HusainAhmed, with more than a touch of pride. “They are priceless.”

Mr Ahmed is the chief executive of Al Ain Properties, the company given the job of developing the Dh179 million open space.

“We are not developing empty land here,” he explains on a tour of the site. “Since the beginning, our idea was to preserve the trees in the park.”

Such redevelopment is rare in the UAE due to land availability and a preference among developers and planners for swift, uncomplicated construction on previously undeveloped, or “greenfield” sites.

It is pattern written into the city’s developmental DNA in expanding new communities on Reem and Saadiyat islands, Khalifa City, Mohammed bin Zayed City, and Al Falah.

So on those rare occasions when existing, “brownfield” sites are redeveloped, like Aldar’s new World Trade Centre and Central Market in Al Markaziya, the site is usually cleared and existing structures are replaced entirely by the new.

Until recently, one of the most notable exceptions to this pattern was Khalifa Park, home to the culturally significant majlis of Sheikh Shakhbut.

Mushrif Central Park, which replaces the old ladies-only garden between Airport Road and Al Karama Street, displays a sensitivity towards natural heritage. The crown jewels of the park are its trees.

When it closed in January last year, the 14-hectare garden was home to about 1,100 trees. The most mature of these are as old as the park, which opened in 1982.

Despite wholesale demolition and redevelopment, as the park is now one of Abu Dhabi’s largest construction sites, a remarkable 940 of the park’s original trees have been saved.

Given that thousands of mature trees have been destroyed in the course of Abu Dhabi’s recent development, this is no mean feat. Of those that were lost at the park most were discarded because of their poor condition or health.

Of those that remained, 800 have been protected on site while 240 that could not be accommodated because of the requirements of the new park have been dug up, placed in enormous wooden crates, and await replanting in positions that correspond with the new design.

Many of these line the entrance to the site, like so many oversized bonsai in some gigantic nursery.

“I experience a moment of silence when I saw how these trees are being treated,” explains Mr Ahmed. “Most, if not all the people of Abu Dhabi inherited from Sheikh Zayed a respect for trees. It is in our blood.

“I have seen throughout my life how Sheikh Zayed respected trees, how roads in Al Ain and Abu Dhabi were diverted because of them, so to see what is being done in this park is amazing.”

Digging up a 31-year-old tree that may weigh up to 40 tonnes, moving it, keeping it alive while it is in storage, and then successfully replanting it is no easy task.

The procedure involves a high degree of risk. In the early stages the plant can die from the shock of being dug up and having its roots pruned, in the same way a human might from serious trauma.

There are also dangers associated with dehydration, relocation and transplanting.

But the park is using a technique of transplanting mature trees that has been perfected over the past 50 years in the US and recently imported by the UAE.

“First of all, you have to decide if the tree is in good condition and health, and whether or not it is worth spending the money to move it,” explains Adam Bradley, the park’s site development manager.

“Then you have to decide what size container you need. The larger the container, the higher the success rate, but the higher the cost as well.”

Some of the larger trees at the park, which include native species such as ghaf, sidr and samur reach almost 10 metres in height and require wooden containers that are more than 2.5 metres in diameter.

After the trees have been assessed, they have to be excavated by hand, have their roots and some of their branches pruned to allow them to be moved, and are then potted into the huge wooden crates.

Before the bottom of the crate can be fitted and the tree moved, the trees have to be left until they start to show signs of new growth.

Once this occurs and the landscape teams are sure the plant has recovered from the experience, the tree can then be moved, an operation that normally requires a crane. The whole process is hugely labour intensive and Mr Bradley refuses to be drawn on precise costs.

“It varies on the size of the tree, where it’s going to, how long it’s being stored for, how it’s being transported, and its location.

“If you need a significant crane or even two cranes to install a tree, that will all affect the cost of relocation. It can range anywhere from a few thousand dirhams to Dh40,000 or Dh50,000.”

While such costs may sound exorbitant, Mr Bradley insists the value of the trees needs to be considered in the round, a position supported by international research into the value of urban trees.

In 2007, the city of New York conducted a “resource analysis” of its municipal forest, which identified urban trees as important to the city’s infrastructure as its buildings, streets, bridges and roads, and identified the tangible and intangible benefits associated with them.

The study was able to assign annual values to a tree’s ability to contribute to energy savings through shading – $27.8 million for the forest, or $47.63 a tree (Dh175) – and to sequester carbon – $754,947 or $1.29 (Dh4.7) a tree.

Value was added for the trees’ ability to remove pollutants from the atmosphere and groundwater, to assist in flood prevention, and even to contribute to the value of real estate.

It concluded that for the $37 the city of New York spent on each of its trees, it received $172 in net annual benefits to the community, and that for every dollar spent on planting and maintenance, it saw a $5.60 return.

It is a picture that has been confirmed by similar studies in other US cities such as Colorado and by studies in Australia and the UK.

But for Mr Bradley, it is the potential loss of resources that is one of the key considerations for saving trees.

“I would sooner see these trees saved rather than seeing them bulldozed and replaced with a new tree. That’s really what we’re talking about here,” he says.

“But look at the cost that this tree has incurred in its life. The cost of producing the water it has consumed over the past 25 to 30 years. How many man hours of labour have been spent looking after it?”

Unfortunately, as Dr Celia Way of engineering giant Buro Happold’s sustainability and physics team explains, trying to make such a calculation is fraught with difficulties.

“The issue associated with calculating the amount of embedded water in something like a tree is the lack of readily available data, and unless you have information about the tree’s whole life cycle it is very difficult to make an assessment,” Dr Way says.

“A tree may have been given the same amount of water every day for the past 10 years, but that figure wouldn’t give you its water footprint.”

The concept of a water footprint was developed in 2002 in an attempt to do for water what carbon footprints did for carbon dioxide.

Implicit in the concept is an attempt to shift our focus away from a concern with immediate consumption, or the amount of water a tree might consume in a day, towards an approach that considers the amount of “virtual water” that lies hidden in the whole cycle of production, transport and consumption.

As Arjen Hoekstra, the University of Twente professor who first described the water footprint explains: “The amounts of water used for the production of goods and services are big amounts.

“Once you realise that water is a global resource and not, like many people think, a local resource you realise that people do leave something like a water footprint, which is the amount of water that you use but not necessarily at home.”

Prof Hoekstra’s organisation Water Footprint Network says the global average water footprint is 1,385 cubic metres of water for each person a year, but the water footprint of UAE residents is 3,136 cu metres, 75.7 per cent of which falls outside the country.

To put this in perspective, 1 cu metre of water equals 1,000 litres of water.

As Prof Hoekstra and Dr Way are keen to point out, one of the most important differences between carbon and water footprints is that while a carbon footprint may be universal, the impact of a water footprint changes according to location and time.

Put simply, the effect of using 100 cu metres of water in a place with a plentiful supply is very different from the effect of using the same amount in a place or time when water is scarce.

Until more data is available, the effect of the water footprint concept on design and development in water-scarce countries such as the UAE is uncertain.

But for Dr Way, even an awareness of the concept and its repercussions should allow for decision making that is more responsible and informed.

“You have to take a pragmatic approach,” she says. “That’s the challenge we face. Given the population density in the Middle East, how do you mediate its effect?

“How do you turn that into a force for good and how can we actually have a beneficial effect on the local environment?”

nleech@thenational.ae

This article was corrected on December 4 at 3.43pm. Mr Ahmed was originally referred to as Mr Ali.