Tree Surgery to a Mature Tree in Abu Dhabi

I recently supervised a major crown reduction on an over-mature Eucalyptus on an historic site in Abu Dhabi. 

I had surveyed the tree last year and made a recommendation to carry out a substantial crown reduction, due to the declining vigour of the tree and the close proximity to people and buildings.

We used a MEWP (mobile elevating work platform) to access the tree and do works to the lower areas of the crown.  The top branches were removed by use of the site crane, which could lift substantial sections of the tree and bring them safely to the ground.  I have some great video’s which I may post at a later time.

Tree Surgery to an old eucalyptus, Abu Dhabi
Tree Surgery to an old eucalyptus, Abu Dhabi

Needless to say, this type of work needs a skilled arborist and crew to carry out, which we used.  If you have complicated tree works that need carrying out, do get in touch…

Lighting Fixtures in Trees

On my last few trips to Dubai, I have been noticing a lot of trees with lighting installed in them.  Whilst these can create stunning effects at night, the correct methods of installation and maintenance are essential for the long-term well-being of the tree.  We have to put the needs of the tree first – if the light effects are more important, then just don’t use a tree!  Much of what I have seen – and this applies world-wide, not just in the UAE (I have seen equally bad wiring in the UK, Chicago, etc.) – is messy and very likely to cause long-term damage to the tree, if it doesn’t kill it entirely.

Incorrect attachment of electric cables to a tree
Incorrect attachment of electric cables to a tree. Cable or zip trees around the circumference may kill the tree, or will become overgrown by new cambial growth.  Excess cable coiled at the bottom is not needed – a light fixed at 10m high stays at that height.

We have to reconcile the fact that trees expand in girth year on year (including palms, though in a different way) through what is termed secondary growth. All this growth happens in the region just under the bark in the cambial layers and produces new meristematic tissue. Damage or restrict this layer and it effects the whole health of the tree.  Cable ties are like a choke collar to a tree; as it grows it gets choked.  Many trees will solve this by growing over such a restriction but this can leave the wood vulnerable to infection and mechanical stress.  Likewise, light mounting brackets screwed directly onto a tree become overgrown and are again a source of potential infection.

messy cabling in trees
This is a mess; transformers should be left on the ground and cabling should be neat and minimal, again, without girdling ties

If the aim of lighting is to create an aesthetic effect, it should not be at the expense of the trees aesthetic, nor of it’s health.  I can’t imagine that the lights above look very good at night, although i wasn’t there to see them on.

There is a correct way to do all this and keep the tree in good health (as far as any interference can be healthy).  If you have such a project, either existing or potential, please contact me to discuss assistance in achieving best practice.

Baobabs, Tree Surveying and a Walk in the Park

On my latest visit to the UAE I had a number of tree-related experiences.

In Dubai, I met with James Palmer from WT Burden, to view the Baobab trees they import from Australia. These trees are succulents, so don’t possess the usual vascular system. As such, they are huge water storage tanks and can live uprooted for two years (I believe the biggest weighed 11 tonnes)! The trees in the picture were planted in January and are just now coming into leaf, as the season warms up. I will follow these closely as I’m intrigued about how well they will re-form a good crown shape.

Baobab trees, Dubai

I also got to have a fabulous green tea in the Four Season’s hotel, which was nearby.  The landscaping there is sublime, with beautifully terraced stone walls and planters to the roadside boundary and a form of living wall with horizontal planters built into a curved wall.

In Abu Dhabi, I was commissioned to carry out a survey on a large tree, which is located on a site I cannot name.  The tree itself is large and in gradual decline, so needs some help.  Following a thorough inspection from the ground and also using a MEWP, I will return in the Autumn/Winter to oversee a crown reduction.  It’s great to see such care and concern being placed on trees, they are the stuff of life!

I also got a chance to visit Umm Al Emarat Park (formerly Mushrif Central Park), to see it finished and to look for the trees I surveyed and made pruning recommendations on, back in 20 14.  It is obviously now completely different, the trees I worked with had all been lifted and containerised for re-use in many different areas of the park. Saw some I could recognise though, like seeing old friends!

This shows a few of the trees in 2014 which had been lifted from the old park and saved for re-use. I surveyed each tree and made recommendations for pruning works, then trained the landscape crew in the correct pruning methods to carry out the works.

One of those trees (Ficus nitida) in its new home and looking happy.

I would like to have had more time there, and will visit again.  I note an on-going need for aboricultural advice there to maintain the trees in the best of conditions…

Irrigation of Native and Exotic Trees in Arid Climates

This article first appeared in Pro Landscaper Gulf.   It is based on tree consultancy work I have undertaken in Abu Dhabi in recent years.


Irrigation is taken as a necessity when landscaping in arid climates.  It is a view that I wouldn’t like to completely contradict, yet I have seen a fair bit of evidence that tells me many plantings, and trees especially, are over-watered.  Of equal importance is the fact that many of the irrigation methods are wasteful of water and sometimes damaging to the trees themselves.

 

Tree sprinkler damage

Lawn Watering with sprinklers is damaging the trunk of this Millingtonia

 

We have to discern the different needs of trees and understand that what is necessary for one species is overkill for another.  I particularly speak of natives verses exotics.  Ghaf and Sidr you will see growing wild and without irrigation but imported exotics need a regular supply.  I have seen Ghaf blown over in irrigated plantings, caused by shallow rooting from an easy water supply.

Bacterial wetrot in Delonix

Bacterial wetwood in Delonix regia caused by overwatering. It also reduces the flowering, for which these trees are famous.

How the water is put on is just as important; pop-up sprinklers in lawns can damage the trunks of trees, causing aerial rooting in species like palm or fig, discolouring bark and causing stress-induced rots to occur in others.  Exotics like the Flame tree (Delonix regia) get over-watered, causing a reduction in flowering and a susceptibility to bacterial wetwood (slime flux). Even drip irrigation is not ideal, as it applies the water at the surface and promotes shallow rooting.  Trees with shallow roots are vulnerable to drought and so dependent upon the irrigation supply – a vicious circle.

Excess surface irrigation is wasteful.

Excess surface irrigation is wasteful.

In the UK, we are used to putting in a subterranean irrigation ring around trees, which gets water to the tree roots at a deeper level.  For watering established trees, perforated tubes can be utilised, inserted vertically throughout the root zone and either manually watered, or connected to standard irrigation systems.  Supplying water at a slightly deeper level means less water used and wasted. A word of warning though – most feeding roots occur in the top 300 – 500mm of soil, so watering too deeply can also be wasteful.

Tree roots growing along the line of irrigation pipes

Tree roots growing along the line of surface irrigation pipes

In coastal cities, problems can arise from a naturally high-level, saline water table.  Halophytes (salt tolerant plants) have evolved to cope with this, but for some imported species, salinity can be a problem.  You also have to be aware of the quality of the irrigation water itself, which if drawn from the ground, may have a high saline content. Get your water supply tested if you are unsure.

 

Ultimately, I believe that planting styles and expectations of “landscape” must change.  A more natural style, with more xeriscaping and use of natives or other arid loving plants from different parts of the world (but from similar conditions), will emerge.  More important, in my view, than using strictly native species, is building plant communities that function and thrive in place without much human care or maintenance.  As climate zones shift rapidly around the world, nature cannot keep up and it will be down to us to create landscapes that sit well in their altered environments, whether native or not.  I believe we can do this with considerably less use of irrigation.  The water we do use should then be grey water (from taps and sinks), which is a much better way to conserve processed water use.

Canopy of Delonix regia

Canopy of Delonix regia

The goal has to be minimal water use, natural, ecologically benign planting and urban environments which feed our biophilic needs for connection to nature.

Zizyphus spina-christi

Zizyphus spina-christi, crown of thorns tree. A native of the UAE