February 7th, 2017 by Mark Laurence

On my most recent trip to Dubai, I enjoyed walking through some of the new landscapes that emerge as projects are completed.  The UAE, along with most regions of the Middle-east has a rather limited palette of plants to work with (although that is growing as new plants are tried). What stuck me, however, was how poor the quality of nursery stock was in some cases and what problems are being created for later, especially with regards trees.

This is not new, nor confined to this part of the world but it bothers me that new areas of urban green are sometimes given a poor start with sub-standard nursery stock, often flown in from other parts of the world.

Simple pruning at an early stage would have improved this tree’s framework, removing crossing and rubbing branches.

Wandering around a residential area in Jumeirah, I came across some newly planted Delonix regia, one of my favourite exotic trees.  At first glance it looked nice, a simple planting of trees and groundcover but on closer inspection I was somewhat dismayed at the condition of the them.  The problems of poor framework were caused by their time in the nursery, not due to planting, although some of them could have been rectified by a vigilant planting crew.

This tree tie – complete with post – must have been like this from the nursery. The post did not reach the ground.

Many of the dozen or so trees had ties left on which the tree had grown around completely, making them impossible to remove.  As the planting is only around two years old (by my estimation), these may have been on the trees from their time in the nursery.  Possibly the planting was older and pre-dated the building they were attached to and the trees then grew around the ties after planting.  Either way, it’s a strong indication of neglect or lack of care. In the picture below, all the bark ridge above the tie may indicate “included bark” – bark sandwiched against bark, preventing live tissue growth and a strong branch collar formation.

The tree tie is trapped with “included bark” at the branch collar, which indicates a potentially weak branch join.

Several problems are arising here: pre-planting care in the form of correct formative pruning (five minutes with a pair of secateurs) and Post-planting care in terms of releasing planting ties – if they were not simply left over from the nursery days.  If there is no way to go back and release the ties, a bio-degradable tie should have been used.

This Ficus nigra was most likely damaged long before it was planted in this location.

Damage to the main trunk or structural framework of a tree might go unnoticed when the trees are small but cause major problems as the tree gets older and puts on size and weight.  This can range from the cosmetic to the potentially dangerous in a large tree and at this stage the remedy is costly and the expertise hard to find.

 

As fast-growing cities like Dubai mature, the needs of landscape shift from creation (in a hurry) to maintenance (at a constant pace).  Skills, awareness of the need for – and absence  – of skills, will become more and more urgent.  If Dubai wants to keep it’s beautiful, green mantle, then there is a whole new phase of arboricultural care awaiting to be discovered and initiated. I have carried out trees assesments and given basic training of correct pruning methods in the UAE, but that has hardly scratched the surface; there is a lot more to be done.

Trees are the urban, biophilic, blanket that clothe and surround the concrete mountains we build.  Trees make hot places not just bearable, but unbelievably beautiful.  Trees absorb dust, cool the air, add moisture and oxygen and enrich our Souls.  We need to honour and look after them, so that they can look after us.

Posted in Arboriculture, Biophilia, Climate Change, Dubai, UAE, Environment, landscapes, Middle-East, Trees, Urban Landscapes Tagged with: , , , , , , ,

July 10th, 2016 by Mark Laurence

This article first appeared in Pro Landscaper Gulf – a .PDF copy can be seen here on page 12.  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

Posted in Arboriculture, Dubai, UAE, Ecosystem Services, Environment, landscapes, Middle-East, Trees Tagged with: , , , , ,

A Living wall designed by Mark Laurence
October 31st, 2015 by Mark Laurence

There is something incredibly exciting about living walls.  Stacking green plants on the vertical plane on buildings, where you’d think they just should not be, goes against the odds.  Yet nowadays they are almost commonplace, and most people have encountered one somewhere.  They cling to life with extraordinary tenacity, usually in a growing medium only a few centimeters thick, with water fed via irrigation pipes. Cynics may criticize and some walls are without doubt better designed and maintained, or use a better system than others, but we should applaud this urban green trend, and encourage it.  We need it.  Modern systems are reliable and use very little water or energy to run.

As a global society we are going through unprecedented changes; now more than 50% of the world’s population is urbanised and this will grow to 75-80% by 2050.  Most of those people are essentially disconnected from Nature. It is now recognised that we have an innate need, called biophilia, to maintain our relationship with Nature.  Not surprising really, when you think how we have evolved, yet the psychological and physical cut-off, over the last 100 years, has been astonishing.  This can only become more pronounced as cities continue to swell, and highly-stressed people produce dysfunctional societies.  If we can green our urban streets then perhaps we can counter this negative effect.  Green walls take up almost no footprint in the urban landscape, not even a pavement width.  All that is needed is a supporting wall and we have plenty of those.  Trees are beautiful and add huge amounts of biophilic interaction into a citiscape, but we find them increasingly difficult to site, due to underground services and growing space needed.  Those of you who read my blog will know that I also consult on trees, so I love them dearly, but I see living walls as having a different role to play and as being more versatile.

Living Wall in a small courtyard garden by Vertology

Living Wall in a small courtyard garden by Vertology

Living walls have physical benefits on the environment too.  They provide a haven and food source for insects, especially bees.  Birds find seeds, berries and of course, insects on the wall and smaller birds are known to nest amongst the foliage.  Living walls are also helpful in mitigation of air pollution; I was involved with designing and plant selection for a wall put up by Transport for London (top picture) to test the ability of plants to capture pm10 – airborne particulates, primarily from diesel engines.  Whilst we need to remove the source of these pollutants, capturing them is a good secondary strategy.  It turns out that walls in a street canyon (where the building height is greater than the street width) cause the air to move in a cyclical manner, so air passes through the foliage of a living wall several times.  Trees can do this, but dense canopies can actually trap particulates down at street level, concentrating them where people are.  Most trees also are deciduous, so have no such benefits in the winter months.

Interior Living wall in Norway, designed by Mark Laurence

Interior Living wall in Norway, installed by a Vertology partner

We can bring living walls into the interior, and in fact in hostile climates, that’s where you’ll find most of them.  Whilst I have designed outdoor walls in climates as diverse as Dubai, Norway (Trondheim, 62° latitude) and Chicago, in such places it is often easier to put your dose of biophilia indoors!  We spend 80-90% of our time inside, so this makes sense.  Such walls also clean the air.  Much quoted studies by NASA have shown that a range of common houseplants (which are basically plants of a sub-tropical origin) are efficient at removing Volatile  Organic Compounds VOCs, such as formaldehyde) from the air. These can be found in concentrations far higher than outdoors, due to the nature of air recirculation and energy conservation.  So we bring the jungle indoors, where we live and work.

Walls have the most drama when they are large, but they don’t have to be.  Small walls in intimate spaces still have a large impact.  This can be a home, courtyard, rooftop or office reception.  Small is beautiful.

A small indoor living wall by Vertology

A small indoor living wall by Vertology

Having worked extensively with living walls over the last decade,  I now consult, design and install them worldwide via my company Vertology Living Walls, and its approved partners.  Grab yourself some biophilia – install a living wall!

Posted in Biophilia, Design, Dubai, UAE, Ecosystem Services, Green walls, living walls, Retail, Vertical Greening Tagged with: , , , , , , , , ,

December 7th, 2014 by Mark Laurence

Last winter I did some interesting work in Abu Dhabi, concerning the care of trees.  I can’t name one of the projects (a royal palace), but one was Mushrif Central Park undergoing a major redevelopment (and now reopened – March 2015).  In both places I undertook a survey of 100+ broadleaf trees (as opposed to palms), assessed their condition and trained staff in basic arboricultural pruning techniques.  Such information is lacking out there as most such trees, with the exception of things like ghaf (Proposis cineraria) and acacia (A. tortilis) are imported from abroad, so knowledge of the necessary arboricultural techniques of pruning, especially of broadleaf trees, is generally absent (palms they are well used to dealing with).

 

As you can see in the pics, the trees in the park had been “salvaged”, which is perhaps not a good word. A specialist tree-lifting company from the US had been engaged to train ground staff in the techniques of boxing and lifting the trees, no easy task in a pure sand soil and 35-40degC – and that’s the winter temperatures. I then had to attend to the care and aesthetics of the tree.  My assessment was that most of the trees had been badly pruned in the past, causing poor crown developments and in some cases allowing disease to enter.

Containerised Trees in the nursery area

Not surprisingly, some of the trees suffered severe shock in being lifted, but most survived, with varying degrees of die-back and then regrowth. Much of the work was simply about deadwooding and the teaching of correct pruning cuts and methods. Access is always the main issue and there was no way to teach the guys how to climb – that is a job for a specialist training school, so we were restricted to a cherry-picker and for the most part, hand tools.

Pruning

Many trees suffer, surprisingly perhaps, from over-irrigation. This causes surface rooting which makes trees dependent upon continued irrigation, plus natives like ghaf become prone to wind-throw from lack of deep anchor roots. Exotic trees such as Delonix (below), grown for their beautiful red or yellow flowers, bloom less well when over-watered and become prone to bacterial wetwood infection.

wetwood

Places like Dubai and Abu Dhabi are developing at an astonishing speed and their landscapes are growing at a similar rate. Knowledge is the thing that lags behind, and it will take some time for this to catch up. I’m sure it will; there is something alluring about creating beautiful landscapes in a naturally hostile climate. This becomes a critical issue in the light of climate change and global urbanization, which is happening fastest in the hotter regions of the world; landscapes moderate climate and make such places livable, whilst biophilia demands that we need close contact with greenery in this urbanised world.

More needs to be done to increase the knowledge and care of trees, including species selection and nursery practice, reducing over-irrigation and teaching good pruning methods, but it can be done. I’m looking forward to the next phase.

Posted in Arboriculture, Dubai, UAE, Environment, landscapes, Middle-East, Trees Tagged with: , , , , , , , , , ,

December 19th, 2013 by Mark Laurence

I am working as a consulting arborist in the UAE for a couple of large projects.  Whilst there, I have been observing the broad state of the art and there is a long way to go in bringing across current best practice to the Middle-East, and I suspect that is so for many parts of the Middle-East and Asia.  Even in my village in Sussex, in the last month tree butchery has occurred, so the UK still doesn’t always get it right, despite a long tradition of arboriculture.

I have always worked in accordance with the advise given by Dr. Alex Shigo, of the US Forest Service.  His investigations revolutionised our understanding of the way trees react to injury, and this should inform the inquiring arborist.  Sadly not everyone inquires.

Delonix trees in a public park in Dubai - note the cracked branch over a footpath!

Delonix trees in a public park in Dubai – note the split branch over a footpath!

Back to trees in the UAE.  What I am seeing is a gradual awakening of interest in the care of trees, and the acknowledgement of the skills needed to carry out that work.  It seems that as more emphasis is put on landscape and more trees are planted, there comes a point when caring for them becomes a higher priority.  This needs to go right across the board, to include the correct pruning in the nursery, this can save many years of bad growth habit, which is not always correctable later.  Prevention is always better than cure. Perhaps the UAE, and especially Dubai, is maturing to the point of switching from development to maintenance. That’s as true for arboriculture as it is for plumbing and building maintenance.

A part of my contracted work is to train local teams in the correct methods of pruning. Basic techniques can be taught, but in the UK it takes three years to train an arborist, so we have to be realistic in what we can achieve. I think it won’t be long before I have UK based arborists over there caring for trees. With the 2020 World Expo now secured, the demand for trees can only grow, whilst in Abu Dhabi a new law requires 25% of all ground space on a development to be landscaped – the demand for beautiful trees has never been greater, nor the need of skilled care more evident.

Posted in Arboriculture, Biophilia, Dubai, UAE, Environment, landscapes, Middle-East, Trees Tagged with: , ,

April 30th, 2013 by Mark Laurence

I’ve just come back from Dubai again, following up on the Biowall green wall installer, Acacia LLC.  Indoors it is much the same conditions as anywhere in the world, but outdoors is a challenge.  Temperatures in the hot summer months can reach 50°C (in the oasis town of Al Ain, it can get to 62°C, with low humidity).  Finding plants that will cope with these levels of heat is not easy.  We’ve had test walls going for nearly a year now, so about to have a second summer test.

 

Biowall at Acacia

Biowall at Acacia (photo taken September 2013)

Indoor walls growing in Acacia's nurseryIndoor walls growing in Acacia’s nursery

 

I have just set up a stage two trial, to run from September, testing an expanded range of 50 outdoor species, mostly plants used there as groundcover.  This will be divided into sun and shade walls, for obvious reasons, and have a rigorous testing regime.

A Biotecture outdoor wall with shade canopy

A Biowall outdoor wall with shade canopy

There are, of course, other people trying green walls. Both of the ones I have seen (outdoors) I fear are likely to fail. This is not good news, because UK experience tells us that a major public failure can set the whole industry back considerably, as it takes a lot of proving then to show that it can be done.

This is a brand-new wall on a new hotel on the Sheikh Zayed Road. Plant are looking very poor already...

This is a brand-new wall on a new hotel using a compost pot system on the Sheikh Zayed Road. Plants are looking very poor already… since died i believe.

So walls like this one cause a lot of problems, which of course, will be corrected with time; the momentum out there for vertical greening is becoming unstoppable.  Systems like the one above that use individual pots to hold compost, mean the root zone is exposed on all sides to heat and wind; keeping such a plant well watered will be a tough call, especially when there is no drainage fitted and it just drips onto the building façade.

Never mind. Pioneering always carries risks and at least they have been bold enough to try.  But the wall should look like this…

Biotecture outdoor living wall at Acacia's garden centre.

Biowall system outdoor living wall at Acacia’s garden centre.

Posted in Dubai, UAE, landscapes, living walls, Middle-East Tagged with: , , ,