Concrete is a wonderfully versatile material, which has been in use since Roman times and with it we can build amazing structures that would otherwise be impossible. Unfortunately it also carries a huge environmental cost, caused mostly in the cement binding used. Whilst gravel extraction is also an issue, for that there are some alternatives such as recycled, crushed concrete.
The production of modern cement (OPC – ordinary portland cement) is a hugely polluting process and produces around 8% of the world’s carbon emissions – at least twice that of the aviation industry. Whilst the Romans used a volcanic dust called pozzolona as their binding agent, until the invention of OPC, we used lime, in various forms. Lime too has to be processed by heat and so is not without it’s environmental cost, but it uses less energy to produce than cement and lime concrete/mortar reabsorbs carbon over its lifetime (if exposed to the air), offsetting some of the initial pollution. Moreover, because it is softer, materials can be disassembled easily, for re-use.
In a landscape, there is ubiquitous use of concrete in a range of structures – walls, paving, sub-bases, ponds etc. some of which could be reduced or avoided altogether. Whilst landscaping will always use an insignificant amount of concrete compared to urban development and infrastructure, there are good reasons to minimise the volume of cement and other hard landscape materials used.
Some of these reasons are for obviously sustainable goals: reducing material/resource input and carbon and other wastes. Equally important in my view, is to increase the soft elements exposed in a garden – soils – and to increase the levels of planting and foliage biomass/diversity. This thinking is about the increase of biophilic benefits.
However, if sustainability is to be given top priority – as it must – then the use of cement has to be reduced as much as possible. This is quite a challenge to us all, as it is not always easy to find an alternative and I don’t suggest for one minute that it should never be used, but it should be reserved for essential structural use only. Even then there may be alternatives. Recycled concrete can make a suitable aggregate (or part of) and low cement alternatives such as CEM 1 reduce the energy and carbon emissions tally.
I have used – and continue to use – concrete in many of my own designs and so this challenge is personal – but then aren’t all sustainability issues.
Let’s look at the different areas of the garden where cement is used:
Many walls use cement, either in mortar or in concrete blocks as well as in cement renders. In this garden (left) we built retaining walls using hollow concrete block construction on concrete footings with cement render and mineral pigments for the final colouring, with concrete paving slabs as coping. As the site was on a chalk hillside, it may have been possible to construct this using rammed chalk or earth. Indeed, we had a surplus of chalk on the site from the house construction and it would have made perfect eco-sense to have used this to build the walls. The walls could have been rendered using lime based mix, and the coping could have been stone. As the chalk hillside is inherently quite stable, rammed chalk could possibly have been used for the footings too. However, there are so many unknowns, and so few UK examples that it is a risk to do this, especially on such structurally critical terracing. Long-term effects of damp creeping into the walls would have been my main concern.
The cost of rammed earth construction may have been cheaper than conventional construction , both in time to do and in material purchase, especially when the removal off site of subsoil is taken into account.
The picture at right shows rammed earth walls in a sustainable landscape I designed for Grand Designs Live, ExCel, 2006. Rammed earth walls are made by compacting subsoil inside timber or metal formwork. The soil must be kept dry so it needs some kind of footing and capping, here provided by cast copings made with recycled aggregates and partial cement substitute (CEM 2 furnace slag). The gravel to the main paving area is a recycled brick/concrete mix, laid through a geo-grid membrane made from recycled plastic. The aim here is to be as carbon neutral as possible. Planting aspired to be edible (you can eat daylily flowers).
Walling alternatives to concrete include:
Cement alternatives/recycled aggregates
Timber walling (railway sleepers etc)
Round pole walling (preferably coppiced hardwood)
Fences & crib-type embankment walls
Brick/stone with lime mortar (brick also has high energy input)
Dry Stone walling
Modern paving is often made from concrete and in some instances it is quite hard to find realistic substitutes. Stone paving is the obvious one but can be expensive. There are many cheaper stone imports available these days, such as Indian Sandstone, which are cost-effective but which carry a high transport and pollution price tag. Reclaimed York paving is highly desirable and of course, reused, so environment friendly but will cost 2-3 times that of cast concrete or Indian Sandstone. Brick is also traditional as paviors but as for walling, still carries a high energy/pollution cost in production, plus is expensive to lay.
For larger areas and drives, self-binding gravels may be one of the better answers, as these form a firm surface, once compacted, without the use of cement. Recycled or local gravels are also acceptable and can be held in place using recycled plastic grids/membranes.
Paving is one of those areas which highlights the question of just what is sustainable. Is it better to use imported sandstone with its high transport miles but relatively low energy production, or locally made concrete paving with cement and aggregate use, but low transport miles? In either case, the (financial) costs may be similar. There are also ethical and human welfare considerations for stone imported from third world countries, especially in terms of working conditions, health & safety and child labour.
Timber decking can be a viable alternative, especially on sites with changes of levels. Local timbers of the more durable softwoods (like Douglas fir or larch), green oak, Sweet chestnut or recycled tropical hardwoods. All new timbers should be FSC (Forest Stewardship Council) certified. New hardwoods should be avoided even if the have an FSC certificate as there is much illegal timber that still gets sold and even managed plantations may still involves some environmental degradation. They certainly have high transport emissions.
Possible paving alternatives:
Recycled stone, brick, cobbles – and concrete slabs
Self binding aggregates don’t need cement
Fired paviors and tile look beautiful, but are still energy intensive
local or recycled aggregates and gravels
Decking can be used where appropriate
Locally produced concrete slabs minimise transport and can have lower carbon footprint than imported stone
Third-world stone may be low energy, but high transport emissions
Even natural looking ponds may use concrete in their construction and formal ponds may be dominated by it. Again choice of alternatives is limited.
Concrete is often used to retain rocks and place protective pads over liners, etc. In many places it may be possible to do without concrete pads, which are often used in a “belt-and-braces” approach to protecting a liner. Felt geomembranes are used as standard as a layer underneath and often inside the liner (this may in fact be degraded by contact with concrete) and in many cases, use of additional layers of felt may eliminate the need for concrete. Felt is usually a synthetic, petroleum based product, so also has its environmental considerations (as do liners!). I have successfully used old carpet as replacement for felt, under the pond (I wouldn’t recommend it inside) but be VERY wary of tacks that may have been used. Non-synthetic carpet will degrade over time, which must be born in mind. Of course, before the advent of felt, liners were simply bedded on a layer of sand.
Where rocks and stones create waterfalls, they are used to form spillways and to prevent stones moving when climbed over or stepped upon (an important safety consideration). It may be possible to use hydraulic lime based concretes for this, although I haven’t tried this out. Perhaps well laid rocks, without the use of cement are the key, which would require a careful re-thinking of the construction method. Nature doesn’t use concrete, but then natural streams don’t retain water within an artificial environment (liner). A more holistic approach to water features, where the roof water and household grey water are recycled and the pond design doesn’t hold a fixed level or amount of water, may be the long term answer.
So looking at alternatives to cement raise as many questions as answers and in the 12 or so years since this article was first written, there has been some progress, but not much. Best advice is to minimise the use wherever possible, recognising the long-term durability and benefits of strength that concrete possesses.
Rain gardens are a relatively new approach on how to deal with water in the environment. In the last 10-15 years, there has been a big rise in the use of SUDS (sustainable urban drainage systems), the practice of delaying the entry of rainwater into the drainage system by the use of swales, ditches and ponds. However, this is generally the domain of engineers who are mostly concerned with their pipework; rain gardens, on the other hand, do the same thing, but are equally concerned with aesthetics and ecology – and so are far more exciting. Easily applied to the domestic situation, but the concept works just as well in urban and commercial design. In fact, WSUD – Water Sensative Urban Design – looks set to take on this wider role in the municipal environment, possibly replacing SUDS.
Having built many water gardens in my life, I decided (in 2010) it was time to build a rain garden in my own home, where I could enjoy it and also monitor its performance. These pictures show the just-completed garden, only a few months old; it also rained right on cue and appeared to be working well!
So what is the “philosophy” of a rain garden: why build one? Well, flood prevention is one answer; if you have ever experienced floods in your area, you have directly or indirectly contributed to them. If the rain didn’t fall on your actual roof, it fell on part of the urban fabric that has been built to support you. Another answer is to re-charge ground water supplies; many urban areas have groundwater levels that are dropping due to the fact that rain cannot permeate the land where it falls (95% of urban land is impermeable). Water tables are also dropping because we are abstracting water far more quickly than it is being replenished.
Rain gardens are a great way to re-connect with nature, opening you up to the experience of natural rhythms and process. It will sit there quietly in hot weather, dry, yet still a micro climate for flora and fauna that like a little extra moisture, in the lowest parts, providing free drainage to the drier areas. When it rains, though, the garden comes to life; water from the roof of your house, instead of disappearing down the drain, starts running into the areas of dips and dry ponds you have created, perhaps having topped up your rainwater butts first. Gradually pools start appearing and maybe in a heavy downpour, water starts running between them. How long it then takes to dissipate will depend upon your soil type; I’m on an alluvial soil, so it is very free draining; on heavy clay it might take days for the water to disperse, and this might mostly be from evaporation. This is good too as it helps re-charge the local hydrological cycle, which is also severly lacking sufficient moisture content, and may well be a significant but overlooked driver of climate change. If you have limited space or can’t allow water to rise beyond a certain level (after all, you don’t want to move the flood potential from somewhere further away, to your own home!), then you might need an overflow which puts any surplus water back to drain, or perhaps (and preferably) to another part of the garden. You will have still considerably delayed the timing of water going to drain, as well as the volume.
In my garden, I have disconnected one of the main roof downpipes (which it turned out was blocked) and used an old steel channel I found when they demolished the adjacent dairy. We have old cast-iron downpipes so I bought a 90° bend and fitted that to direct the water into the chute. I then dug a channel and partly lined the bottom with plastic, because our ground is very free draining and I wanted to connect this to an existing small water feature, so that this was topped up by rainfall. Surplus water is then dispersed to the sides, through the planting. If I were designing this from scratch, I would put the pond before the raingarden, so this was topped up first. Having said that, this section of the garden has always been incredibly dry and I’m hoping that the ground will, over time, recharge itself and things will grow better. This dryness is evidenced by the fact that we have a young fig growing well, right by the downpipe.
In periods of heavy and prolonged downpours, it may be that the pond will overflow; this will happen at the back and will disperse out away from the house under the bushes. With our soil, I don’t see the need for any further overflow drainage.
The roof section that feeds this downpipe is about 50m2, south facing. We get on average 50cm rain per year, so this should capture 25m3/year. This morning in light/medium rainfall, the chute was delivering 3 litres/minute (nowhere near the rate of a hosepipe). The rain garden is about four metres long and I’m not sure how to measure the drainage rate of soil, apart from having the plasticity index measured in a lab but over time I will use these figures to try and calculate how much water is passing through the system; in theory 25m3/year.
I was sent this picture (right) of a rain garden I designed for a client around the same time that I made mine. What a great picture, it gets right to the heart for so many issues about life, play, learning, experience, the elements. We tend to over-design our environments for safety, yet end up sanitizing them to the point where life becomes uneventful and we loose the richness and diversity that being connected to nature gives us. On a rainy day most kids are sat in front of the TV; I think this as a much better option…
The soil in this raingarden is a heavy clay and so holds the water for longer. It is bigger than mine and would need to be to increase the percolation area. You can also see that mine is more planted and this is again a condition of its function – theirs was designed to be a play space for the children (which is why I’m so pleased that it is successful). When they have grown up, it can be planted more intensely. It also created a feature in an otherwise rather awkward, narrow, North-facing space.
Rainwater management isn’t just for large commercial or public-realm sites, it can be done in your own garden too, with multiple benefits to environment, garden, wildlife and of course, you.
The emergence of the idea of resilient planting is a response to a number of different pressures which all have one underlying cause – climate change. Whatever the cause – and I’ll get on to that later – I see it as the most exciting change to the way we design our gardens and landscapes.
Last year we had one of the hottest summers ever recorded and it serves to heighten awareness of the vulnerability of some plants and garden styles to the increasingly erratic climate we are dealing with in the UK. We seem to swing from one extreme to the other, and this is only likely to get worse. I’ve witnessed a number of stressed plants in my own garden but feel relieved that most have thrived throughout the heat, without any watering on my part. this is down to soil, drainage, micro-climate and above all, plant choice.
Ballota pseudodictamnus, a Mediterranean sub-shrub with grey, felted leaves, loved by bees.
We garden on an alluvial coastal plain, and are fortunate to have a very free-draining soil overlying a clay substrate. It gives us fertile soil, great drainage and a moist sub-strata within the reach of most plants (many areas around us are of much heavier clay). A large section of our front area used to be a paddock with a rubble driveway and this now forms the basis of much of my dry garden. Some rubble was removed and topsoil added, but a lot of areas are still rubble-strewn, not unlike some rocky soils. The down side of all this is super-fertility and a soil filled with weed seeds, bindweed and couch. To be honest, I’d have preferred a poorer soil.
When thinking of resilient planting, we have to match our plant type to the environment; we also have to think, long-term, of how our environment might change in the coming years. This is not so important when dealing with short-lived plants such as herbs, sub-shrubs and perennials, but is super important when dealing with long-term structures, especially trees. This is doubly true when we look at the potentially disastrous effects of imported pests and diseases that we are having to content with. Climate change, especially milder winters, mean that exotic pests are happily making a home here and wreaking an unintentional devastation to trees such as our native ash and even oak.
Phlomis russeliana, after flowering. The stem leaves have since dropped, leaving a brown, architectural structure.
No-one can say exactly which way our climate will go as the world hots up; we know we (in the UK) will always be maritime, because that can’t change, but as the Jet stream (wind currents) varies and the Gulf stream (water currents) weakens, we don’t really know what kind of climate we’ll end up with. We can only plan for extremes, and select our planting choices with that in mind. In this respect, the “new perennial” or “naturalistic” planting isn’t necessarily going to be the toughest choice as they come from a continental climate which generally have hot summers and very cold winters. Prairie plants tend to get out-competed here with our mild winters and grasses and forbs that can grow all year round, given mild conditions. The aforementioned fertility (at least in my garden’s case) also doesn’t help as wildflower meadows/prairies tend to have poor soil which helps keep the grasses from assuming dominance. During the heat-stressed weeks, I noticed that where I have perennials like Echinacea and Veronicastrum (in moister areas than the dry garden), they suffered from the lack of water. which resulted in the Veronacastrum flower spikes looking stunted. for more moisture-demanding planting, sub-surface irrigation using harvested rainwater might become a necessity.
To my mind though, if you need irrigation you’re working with the wrong plant-types, trying to grow plants that can’t naturally cope with the conditions that predominate. Save your water for the newly planted and the vegetable plot and for this, consider rainwater harvesting, rather than mains. When selecting plants, see what grows well, both of native and non-native origins and build adaptive micro-ecologies. Our climate is changing faster than the current ecosystems and ecologies can cope with and we need to do whatever we can to build new planting that is of maximum benefit to local wildlife, as well as ourselves.
It’s an exciting time to be a gardener, for there is no place now for the self-indulgence and nature-control-freakishness of the past. What there is a the possibility of co-creating new ecologies that adapt to changes, halt decline and make our local wildlife vibrant and healthy.
Along the way, we can create the most stunning of gardens!
NOTE: This article was first written in 2006, so some aspects have been updated to reflect current realities.
Biomembranes is a term I’m borrowing from biology (the structure bounding a cell) to describe the outer skin of future self-sustaining buildings. I have stated elsewhere that I believe that for the built environment – and therefore our societies – to become sustainable, every building and community must deal with its own wastes, generate its own energy and provide nourishment – both physical and emotional – for the occupiers. Only by the creation of truly independant, carbon neutral buildings can we achieve this.
This would be a subtle and far reaching art, not easy to achieve but I believe that the rewards would be many, not to mention necessary. In this respect, the science of biomimicry will play an important part, for example, in developing paint-on polymers that photosynthesize energy, or tensioned fabric five times stronger than steel or kelvar, made with no heat or pollution, just like a spider’s thread. Whilst we haven’t perfected those products yet, let me list some of the benefits we can look to achieve in the near future:
horizontal and vertical skins of living plants that insulate, filter the air of dust and pollution, dampen noise and attract wildlife. Current living walls are used sparingly as art pieces.
composting and filtration systems that clean the building’s waste and return nutrients and water to the biomembrane and surrounding landscape.
Algal biofuel production using building wastes.
interior landscapes that provide internal cleansing and beauty.
blurring of internal/external space.
energy generation as integral with the building fabric as passive solar/pv/wind.
pedestrianised streets as wooded valleys or urban forest gardens.
SUDS drainage to filter excess water straight back to the local water table.
pedestrian/bike/electric vehicle shared surfaces removing car domination.
increase of social space by good design.
Some of these ideas are becoming well established, such as green (or living) roofs and walls, others are being played with by a few, but as yet, no one is trying to pull all these things together into a cohesive whole system. I am thinking of concepts such as combining vertical greening with greywater filtration, active cooling systems, air purification and algal biofuel from building wastes. I have recently been inspired by the work of the world-renowned architect Ken Yeang (Llewelyn Davies Yeang) based in London and Malaysia. Ken has worked extensively on the concepts of bio-climatic buildings and so his ideas are very close to my heart. Furthermore, one of his main concerns is the organisation of internal space by social structure, rather than by economic return on investment. This very much reminds me of the work of Christopher Alexander (see Pattern Language); despite apparent differences of style, the underlying philosophy is similar, Ken’s work placing it into a modern urban context.
There is a lot to do but the future will need autonomous
bio-buildings that take care of themselves without external input, other
than sunlight and human organisation. The main challenge is then to
retrofit these systems to existing buildings, which will always be the
large majority of available building stock.
Meanwhile, take inspiration from the work of Hundertwasser (top right) and Ken Yeang (bottom right). The application of green technology, biological water filtration and the use of every surface to create living, breathing buildings shows that humanity can and will grow up and see beyond the profit line, which so dominates and limits current thinking.
This article was first published in 2007 and has been updated 2018.
Future gardens will be an integral part of a living bio-system that is part house, part garden, an energy conserving and production environment. It will also be a resource for water retention and cleansing, food production area, biomass and environmental haven. Above all, it must continue to be a sanctuary for the soul and from the world at large.
Why do I say this? We cannot consider the future of gardens without accounting for climate change, which is now having a tangible impact on us all. The 2018 IPCC report says we have 12 years left before things reach the point of no return. Whilst there is less talk now about global oil reserves peaking and that energy will be in increasingly short supply, it is still true that we have a long way to go before we have a fully renewable clean energy supply chain. Whatever the outcome, big changes are on the way.
So when we look to the future of our gardens, it’s not so much a matter of what style or vogue will be popular, for such things come and go and in this context are not particularly relevant. You might imagine it is a case of asking what will our climate be like and how will gardens adapt. Yet to talk only of adapting plants to suit the changing conditions is actually to miss the main opportunity for our gardens to become part of the solution to global warming and perhaps, even a core part of our individual – and so collective – survival.
House-garden water capture, cleansing and re-use schematic.
That might sound ridiculous in the face of such monumental problems but I don’t think so. If we all decided to make sure that in our personal lives, we were “carbon neutral” (or as close as possible) then energy demands and pollution from domestic use would drop considerably. At a rough estimate, gardens in the UK occupy about 4500 km2 of land area (Davies
et al. 2009), mostly in urban and suburban areas. This makes them a precious resource and opportunity for change on a big scale.
The first thing we have to do is start looking at our environment as a living bio-system; in this case, the house and garden, with its connections to the wider world (air, earth, wind, rain, food, materials, waste, energy, communications). Think of the garden as one cell in a big organism. Almost all the elements this cell needs to survive are coming from outside, beyond its sphere of influence. Yet the way that cell is constructed, used and connected to its immediate surrounds (garden) could, if designed correctly, reduce its dependency on external manmade systems. To decrease those we must increase our connectivity with natural systems, namely the sun, wind and rain. To put it more directly, with have to reduce to a minimum the inputs and outputs of our homes.
A fedge (fence-hedge) uses biomass grown in the garden to create new boundaries. Good for wildlife and resource conservation.
Those items which we cannot produce internally need to be sourced from outside as close to us as possible. Therefore neighbourhood and regional systems need strengthening to minimise production/transport costs. This is particularly true and desirable for food products, but also building materials etc. For that reason, even if we manage to live off-grid – the ultimate, but extreme, conclusion to this line of thought – we cannot do it all alone and live in splendid isolation, nor would most of us want to. Many bio-systems will only work efficiently when connected together to give sufficient inputs to allow them to function properly (for example, reed-bed sewerage systems). Local community-generated bio-systems are essential to a sustainable future.
The main areas which the outside garden spaces could deal with are:
Passive solar gain (microclimates)
Water saving and (grey water) cleansing
Waste recycling (composting)
Increasing site biomass
You may think this all sounds very philanthropic, but where is the incentive to expend all this time and money “greening up” our homes and gardens? Some of the incentive will be economic; for example metered water users already consume about 15% less water than unmetered and government will gradually introduce a number of Carrot and Stick measures. But as cost of pollution will have to be met by industry and so, by consumers, simple economics means that inevitably everything will get more expensive. For many people, I suspect that having a lifestyle that gives independence and doesn’t add to pollution will become increasingly desirable, as we all witness first or second-hand the effects of climate change. Whilst we all see the horrors of hurricanes and droughts in distant lands, at home (for me, the UK) we see increasingly severe flooding etc. right on our own doorstep. Less dependency on outside systems will give increased sense of security in an uncertain world.
In all of this, beauty and relaxation will be paramount, so gardens will still fulfil this most traditional and personal of roles, giving us joy, relaxation and sanctuary. For example, looking at a beautiful water system of rills and planted gravel filterbeds is made all the more exciting by knowing it has a useful function and is saving resources.
A rain garden which captures roof-water and allows it to infiltrate the ground
For these principles to be taken up by the average garden-owner and made successful, we must resolve two conflicting issues: the subject needs to be driven by a sense of fun, adventure and positive aspiration to really make a difference and yet we must also avoid the “dumbing-down” or over-simplification of a complex topic, something that can occur when it appears in magazines and TV shows.
An example might be solar panels: it would be wonderful to run your garden pond pump, shed, or garden office from solar panels – no cables to the house to bury, a good eco-friendly solution. But you have to balance that ideal with the cost of initial installation (probably greater than laying electric cables from the house), the limitations of supply and the increased maintenance that may be involved. Having got your solar supply, you might be frustrated to find that you can’t charge your battery mower if you didn’t purchase a high enough generative capability. This is typical of a fragmented approach to sustainability – it’s a start but not really useful just thinking of the power to your pond and ignoring that used within the house, or your car.
So where are we? Standing on the threshold of an exciting new future, I would say. Technology and information is available as never before, and hooking up to the IoT (internet of things) is great fun and useful too. The brightness, however, is troubled by the looming stormclouds on the horizon and the knowledge that the societal cost of failure is high – and will be witnessed by ourselves but paid for by our children.
I do firmly believe that we can all make effective choices in what we do and in what we demand of the world, of business and our societies. We have to make rational choices and sometimes temper our own personal indulgence. Gas or electric patio heaters may be a nice luxury but the environmental damage is not justifiable. Maybe a log burning fire basket is, provided we do other things to counter the carbon emissions, such as growing more bio-mass. Extra woolly jumpers may simply be the best bet along with passive solar designed spaces! Most issues simply come down to us making informed decisions and balancing personal ease with environmental sanity.
Remember, what sounds “eco” or fringe today, is going to be tomorrow’s norm. Get out there, explore ideas and enjoy being the change!
A problem, or an opportunity for a new landscape paradigm?
I was recently working on a tree project in Abu Dhabi when I came across a derelict site which intrigued me with it’s range of exotic self-seeded, non-native plants. The site was next to the Corniche and sandwiched between the Formal Park, my hotel and Capital Gardens. It struck me initially as the perfect basis of a xeriscape, as all the plants (mostly trees) were thriving without irrigation. On closer inspection and identification of the species involved, things got more complex and raised a lot of potentially conflicting thoughts and issues.
A natural Xeriscape
The site was clearly awaiting redevelopment and the plant invasion was opportunistic. Nothing that I could identify was native, yet all seemed happy there. When you see the list, you might understand why. Amongst the plastic and litter I identified:
Of those plants, the P. juliflora was the most robust and when you look at its reputation, that is of no surprise. It was of landscape scale, lush and greener than anything in the adjacent parks. It’s form, leaf, flowers and seeds are attractive from a landscape perspective. Yet this is undoubtedly the most controversial plant on this list – some would say alarming. A Native of arid zones in central and South America, this was, like so many others, introduced into the UAE in the 70’s as a forestry plant. Lauded as something of a super-crop tree, it is tenacious, vigorous, provids fuelwood and stock-feed in the form of abundant seeds. The latter, it turned out, were a problem in that they are spread by cattle and are extremely aggressive. Plants also regenerate rapidly from the roots when cut back and they reputedly produce biochemical inhibitors to suppress competition (allelopathy). With no natural competitors in the UAE and roots that can descend 50m in search of water, they out-compete native flora, even their cousin, Prosopis cineraria (ghaf tree).
Prosopis juliflora flowers
P. juliflora has a low, mounding habit, attractive from a landscape point of view.
Also on the site were a number of Banyan trees, Ficus benghalensis, which seemed to be growing happily. Another tough survivor, it should be borne in mind that the water table here is likely only a metre or so below ground, although it will have a high saline content.
Then there was Eucalyptus glaucescens, another forestry/amenity introduction of the 70’s, also known and now generally avoided for its aggressive roots, yet here looking beautiful with its grey, lanceolate foliage. This was the tallest tree on site.
Eucalyptus glaucescens, showing adult foliage
Of course, there was the ubiquitous Conocarpus lancifolius, widely planted still yet also recognised and a danger to any nearby drains, and on it’s way out in popular use. Except it does make such a good tall hedge, and it has a much nearer native origin, coming from Somalia, Djibouti and Yemen. I’m not sure that the UAE landscape industry is ready to ditch it just yet.
There was even a palm, Washingtonia robusta, self-seeded around the place. Much of it was to be found growing underneath the canopy of the P. juliflora, so that at least is not put off by any allelopathic biochemicals from the Prosopis.
I believe this legume is Sesbania sesban, more commonly seen with yellow flowers. Rose-ringed Parakeet
Inhabiting, or at least visiting the site, was a Rose-winged Parakeet. Another exotic invasive with beautiful form but aggressive tendencies; it seemed appropriate to the moment, somehow.
What does this mean for future landscapes and ecology?
From a conventional ecology point of view, these plants are all threats, and the threats probably outweigh their usefulness. So why am I even talking about this? Clearly, the move towards more naturalistic landscapes draws heavily on native species and would shun all of these species.
Except we have climate change.
Climate change is the elephant in the room, when it comes to ecology, in fact when it comes to sustainability generally and a livable planet overall. That we have already moved beyond vital tipping points is highly likely; that climate zones are moving away from the equator at a rate too fast for nature to adapt is a fact. Flora and even some fauna just can’t move regions that quickly. They will adapt, eventually; but those that are rare, specialist and struggle with change, will die. The tougher generalists will adapt and survive. Nature will build a new ecology to reflect the new reality, and it doesn’t mind if it takes a few thousand years to do so. Only we humans mind and so, if we are to survive, we must adapt our environments to fit the new reality. It is a sad fact that many cherished plants will eventually die out or move zones. In the UK, I dread losing our native oaks (I view these as our ghaf tree equivalent), yet we may get Mediterranean species to replace them, such as holm and cork oak.
If you are already positioned in the arid equatorial zones then you have precious few plants that will form your new ecologies and landscapes. Perhaps the plants I have described above will be UAE naturalized-natives in 100 years’ time and the ghaf and sidr may be gone, or diminished, or moved north. I hope not, but before we spend vast fortunes on eradication and control of non-natives, we should look to the future. These aggressive invaders may just form the landscape of our children; I know I’d rather live with a landscape, than none at all. If there is no landscape, there is no life. They may, in fact, be here to save us.
Once we grasp this fact, we can look at building new landscapes to suit our changing environments. I’ve written about this before and you can read the articles listed below. We must be vastly more holistic in our thinking in order to do this and broaden our horizons to understand the new future. Technology will help us to monitor, collect data and produce working strategies. Robotics and drones will help manage and control plant communities. Alongside that, we need a vastly better understanding of soils, microflora and fauna, for the bit of nature that we see is just, literally, the tip of the iceberg. The selection of tree and shrub species for adaptation is easy, we get this wrong when we don’t deal in whole context thinking eg. only thinking of forestry or ornamental benefits.
The challenge ahead is huge but in a weird way, exciting; it will challenge the human race to grow. There’s a whole new science to develop and we’d best get on with it.
I’m pleased to have launched a new website and blog dedicated to this aspect of my work. Over time the blog will become a useful resource to all those interested in the care of trees in the Middle-East. My focus and experience has so far been within the UAE but the tree range is similar in most GCC countries. treecare UAE
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 struck 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.
The way in which we design, create, maintain and use urban landscapes is likely to change radically in the next 15 years (in fact, modern society is in for overwhelming change). Urbanisation, climate change and the rapid rise of technology and artificial intelligence (AI) will see to that. Don’t think that the rate of change will be the same as has occurred in the previous 15 years, for technological growth is on an exponential growth curve, not a linear one. Cities and systems are becoming smart, connected to the Internet of Things and that is just for starters. So how will this change the way we design and use our urban landscapes?
Firstly, we know that there is huge movement of populations from rural to urban life, especially in the developing worlds and most markedly in Asia. This creates huge pressure for new urban infrastructure and this is not always well planned growth, especially in terms of forward thinking to account for future changes. Nonetheless, it is happening and happening fast. The UN expects 66% of the world’s population to be urban by 2050, by which time there will be 9bn of us – so 6bn in cities. Mega-cities have to grow in a way that sustains huge numbers of people.
Secondly, climate change is also occurring at exponential rates, raising the difficulties of living in any environment but with especial problems for mega cities, most of which are in coastal regions and subject to rising sea levels and worsening weather patterns. Cities are hotter than the surrounding land due to the nature of materials used, whilst heavy rainfall brings flash-flooding. In arid countries, built environments are in danger of becoming too hot for humans to inhabit. Cities will have to take on these challenges, generating micro-climate.
Thirdly, technological change is happening exponentially and this will impact what we do, how we live, how – if – we work and how we tackle the above problems. Some view the challenges and changes with fear, thinking they will only exacerbate problems. They could do, anything can be mismanaged (such as a planet) for example. I foresee that technology is actually the only way we are going to get ourselves out of the mess we have created, the only thing that can act on the vast scale needed to re-balance an out-of-kilter Gaia.
When we take these three factors into account, we can see that the future of urban landscapes has to be so much more than the addition of the odd pocket-park here and there. Landscapes have to mitigate the environmental factors, make huge mega-cities liveable for a population increasingly disconnected from nature and provide meaningful lives in an era when many of us may not work in the way we are used to.
Weedy and neglected landscape plantings are all too common. No-one wants to pay for maintenance
How will cities become smart and use this to better the environment? If we are looking to increase the amount of urban landscaping significantly, then the first issue to tackle is cost of maintenance. No one wants to pay for maintenance and often, no one does. How many planted landscapes do you see smothered in weeds, wrecking or negating the designed purpose? Or municipal plantings and car-parks where plants inevitably die and are never replaced, leaving huge gaps. Shrubs hedge trimmed into amorphous shapes because that’s the quickest way to “maintain” them. It’s a poor standard and it’s all we’re going to get – no-one is going to pay for trained horticulturalists to do something better.
Landscape lobotomy: maintenance is the quickest, cheapest possible
Yet there is an interesting possibility – automation is likely to remove nearly 50% of jobs in the next decade, especially low-skilled or repetitive ones. In the landscape trade, there are already semi-autonomous strimmers and grass-cutters on the market, how long before we have horticultural robots maintaining our landscapes? All the technology is already here, prices are falling and an uplink to an AI would identify every weed known, give the correct procedures, know how and when to prune every plant in common cultivation. Robots would work long hours without tea breaks! If basic maintenance getters a lot cheaper, we can have more landscape and such robots would be cheaper, eventually. Living walls would be a prime candidate, with a simple maintenance cradle (much like a 3D printer head) that crosses the wall with a maintenance bot on it. I’ve seen so many potential living wall projects fall at the maintenance-cost hurdle. In such a scenario, displaced maintenance crew can retrain as bot-supervisors or true horticulturalist for private clients.
Horticultural robots will make maintenance cheaper and more effective.
We’re going to have to do more than just make maintenance affordable; rather, that is the factor that releases the possibility to do more urban landscaping. Many of the elements we need to put in place are already in existence and being used, but we need to join the dots and think holistically. For example, green roofs are seen as a separate trade from green (I prefer living) walls. Instead, we need to be talking of biological membranes (biomembranes) for buildings, a whole-system concept, where the living skin regulates the internal environment, filters pollution in both directions, dealing with generation of energy, cooling, clean air and water. Living walls that currently use potable water for irrigation when they could be cleaning up the used greywater that all buildings generate is another example.
Building Biomembranes regulate building ecology and create vertical landscapes
Systems that provide services that are of consequence to the functioning of a building, street, or neighbourhood need careful management and control, much of which will become automated. In just the last year, for example, new irrigation controllers have come on the market which not only are connected to you via internet, they also connect to the nearest weather station and adjust their regime according to the conditions. I use these for living walls; I do not advocate any irrigation for horizontal landscapes in temperate climates. But things will move beyond this, with AI monitoring ground moisture levels and moving harvested rainwater from one holding system out to another part of the city where it is needed. And urban farming – especially vertical – will be a large part of mega-city greening, although it might not be on display. Sophisticated hydroponic systems are springing up in warehouses and roof-top polytunnels all over. Such food can and should be organic, local, healthy, nutritious.
A smartly connected landscape means we can maximize the benefit it gives to the people who live, work or pass through it. With the majority of people living in urban mega cities, we have to create an environment that is fit for ultra-dense urban living. As these metropolis’ grow, people will have less and less daily contact with Nature, which is not good for our deeper wellbeing. Biophilia is our innate need for contact with the natural world: plants, trees, flowers, insects, sunlight, water, earth. A concrete jungle is not a substitute for the real thing but we mostly won’t have time to “get out there” and experience wild Nature.
I think inner city pollution will blow over – excuse the pun- in the next 5-10 years as we start a massive switch over to electric transport, most of it driverless. In fact, drone taxis are already under development and as buildings and living habitats reach skyward we can expect the landscape to move with them. It will become commonplace to have high-level dronepads – even private ones. Some people might not even go down to the ground much! So landscapes and biophilia must come to them. Fortunately, there is a rash of building-integrated vegetation going on and I see this trend increasing. Incidentally, if you wanted more good reasons for using bots to maintain planting, imagine working on living walls or trees that are 50 stories up!
As for the wider environment and the looming crisis of climate change, I can only hope that emerging nanotechnologies give us the tools to clean up our act and neutralise the positive feedback loops we are creating. Scientists are already working on nanotechnologies which capture and convert carbon into useful materials and one day such microscopic machines may roam our land and seas, removing plastics and other dangerous waste. If this is done at a molecular level, we turn problems into resources. We’ll be printing our houses (already being tested) compounds made from waste materials but without the current worries of using say, bricks made from recycled plastic which off-gas VOCs. We can only hope these technologies emerge before it’s too late to save the climate in a state that we can survive in.
So the next 10-15 years are going to see change at an unprecedented rate and it may not all be a smooth ride. I am excited by it however and think that there is much to be done to ensure that we create new urban environments worthy of habitation and that we take care of all environments and indeed the whole planet. Smart cities are coming and at their best they could loosen our imaginations and liberate us from a monotonous life of work and stress. Let’s make that the scenario that happens…
Almost all urban landscapes are contrived and designed, due to their artificial nature and short timescales of development and use. We see increasing use of mature rootballed trees and extensive hard landscape and this is normal for intense inner urban areas; I do get concerned that the increasing complexity of urban planting systems divorce trees particularly from their natural functions and prevent the occurrence of the biological interactions/communities that go to make up an ecosystem. For example, I have seen trees planted whose surface levels are around a metre below the surrounding paving level. No matter how well designed, this seems fundamentally wrong to me.
So I’m thinking that there must be a way of dealing with the majority of less intense landscape zones (especially where there isn’t the financial budget that a high-end development attracts) to provide urban regeneration, ecological restoration and biophilic connection, all on a modest budget. This would create a new method to allow for wide-spread adoption in urban and suburban zones. I think the solution comes from Nature’s own process of natural regeneration and a developed philosophy of minimal (but specific) preparation.
silver birch are pioneering species for natural regeneration
Starting from the observation that Nature is very efficient at regenerating itself, what can we do? Too often, I have seen unnecessary interference in this process. I still recall that a few years after the great storm of 1987, I walked through some nearby National Trust woodland of pines and birch. A great deal of damage had been done with many trees blown over. Birch had however, regrown abundantly from dormant seed and was already three or four foot tall. The NT then sent in the bulldozers to clear out the fallen wood so the area could be – replanted. I watched them tracking over all the natural regeneration. Why didn’t they just leave well alone? The restoration of the woodland was only slowed down by such clumsy interference and this was not even a productive forest.
If we simply broke up paving in our urban centres and loosened up the sub-base, what would happen? Nature would soon find a footing and things would start to grow; however, that process would be too slow and unpredictable for human sensibilities. So what if we did a little more, adding a small amount of topsoil to the rubble, planting small (1+1 year transplants) bare root trees and shrubs, with plugs of understory forbs, ferns and grasses. Starting so young, we’d generate a successful community in no time. These could be designed as narrow ribbons – two to four metres wide, inserted into suitable wider areas of paving.
An urban area suitable for natural regeneration
The above area was one I thought would be suitable for such an approach; there are many such areas throughout all urban spaces. They cry out for regeneration, yet seldom can this be done for lack of adequate finance. Below is a quick sketch showing how it might look.
Sketch showing regenerative planting
The benefits of such an approach would be huge. It would cost far less than using a traditional approach to landscaping such an area, maybe half (I haven’t costed it!). The care would move from maintenance to management, using a rotational coppice methodology, rather than trim and tidy (which always ruins a plants natural habit. Biodiversity would be hugely enhanced, air pollution mitigation would increase, wind buffering, urban heat island reduction, stormwater runoff (they would act as rain gardens) and of course, our biophilic needs, our connection to nature.