why we love trees

ABOUT SLA

SLA is a Copenhagen- and Oslo-based design company with architects, landscape architects and urban planners operating within the fields of urban space, city planning and landscape architecture.

SLA creates modern, resilient cities that inspire com-munity and diversity through the innovative use of nature, design, climate adaptation and technology. The studio’s projects solve some of today’s hardest urban problems while creating genuine amenity values that, in an unorthodox way, add an extra layer of meaning and quality to the everyday environment.

Drawing on its strong Nordic roots SLA has realized numerous projects in Europe as well as in Asia and Africa.

CONTACT - [email protected] - www.sla.dk

SLA COPENHAGEN SLA OSLONjalsgade 17B Sørkedalsveien 6Pakhus 2, 3.sal Pb 7057 MajorstuenDK 2300 Copenhagen N 0306 OsloDenmark Norway

Many people think that trees represent the biggest and most important CO2 intake in the world – but they are wrong. That being said, trees are essential for the planet’s CO2 balance, but is that enough or are there other and more fundamental reasons to plant and love them? In our work, trees are planted for sustainable and functional reasons – but the species are chosen and composed depending on aesthetic quality, sensibility and atmosphere. We design with nature for people, plants and animals.

We believe that the livable city is made for people, not cars. We believe that future urban spaces are multifunctional, but they are first and foremost created for people. People need nature, and by formulating a new type of Urban Nature we can achieve balance. This is an Urban Nature of high biodiversity, great aesthetic power and many different functional properties –from rainfall management and climate change adaptation to protection against urban heat islands and shielding of buildings and infrastructure from wind and weather. But, first and fore-most, an Urban Nature that creates the best environment for the users of the city. Trees are the core element in urban spaces. Trees offer sensuous experiences and play a significant role in peoples’ ability to learn, live and socialize.

We love trees because they tell stories. Stories about life, his-tory and nature. Trees take shape according to wind and sun – they are the kind of trees we love. At the new headquarters for Novo Nordisk we have designed a nature park full of leaning trees, dead trees and trees of many different sizes, shapes and expressions – just like in nature.

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Bark is another example. Bark is at once living and dead, growing and fractured, a protective layer and an integral part of the tree. Once you become aware of the sensuous qualities of bark everything else quickly fades. You could say it is a mat-ter of not being able to see the forest for the bark.

In our expo at the Venice Biennale 2014 we placed tree roots inside the building. Nowhere else is the power and the feeling of nature stronger than in tree roots: the crooked branches, the amorphous sequences, the non-geometrical, the non-hierarchical. Tree roots are all that architecture is striving for – but can never reach. They are the order of nature.

Trees are, in other words, essential to people for many reasons, which will be shown in a variety of examples in this book. This book is a conclusion of more than 20 years experience, knowledge and research working with trees. Because of our love for trees we now share all of it with you – enjoy!

Climate change around the globe promises more heavy rain in the future, hence a greater risk of flooding be-cause our sewers have in-sufficient capacity. Trees can help relieve the pressure on our sewers. When rain hits their lea-ves it stays there for 10 to 20 minutes before it falls off, di stributing the water to the sewers over time.

Their root systems ab-sorb water from the ground, whereupon the water is trans-ported to the leaves where it evaporates as the tree tran-spires. Water, thereby, is sent back into the atmosphere ra ther than accumulating in the ground. This leaves room for new rain to be absorbed rather than surging into your basement.

DiD yOUr ceLLAr fLOOD DUring The LAST cLOUDBUrST?

Normally nature sustains it-self in ecosystems with a rich flora and fauna diversity – trees, bushes, birds, insects etc. – which are mutually de-pendent. Partial or missing planting causes imbalance and puts the housing market un der pressure, leaving birds and insects homeless. When they leave the system, nature

cannot sustain itself and be-comes expensive and time-consuming to take care of. By planting the right com bination of trees, biodi-versity is increased and the ecosystem is strengthened so it can sustain itself if at-tacked by epidemics such as elm disease.

The hOUSing MArkeT iS UnDer PreSSUre - heLP A BirD TO neST

Where do burglars have the best conditions – in vibrant areas with good neighborli-ness or in empty voids where people stick to themselves? Green areas invite pe ople to spend more time outdoors. Lush, attractive sq u ares and streets pro mote interaction and a se nse of community.

Thereby, a natural form of ‘neighborhood watch’ emerg-es, making conditions more difficult for criminals. Studies show that res-idential areas in green sur-roundings have half the num ber of crimes seen in bar ren residential areas.

TreeS fighT criMe

Normally, when dealing with soil contamination prior to building, the methods in-volve excavation, freight and disposal of the soil and sometimes even the import of new, clean soil. These are expensive and polluting methods which can be made redundant by planting phy-toremediating trees on the contaminated lot. Phytoremediation is a natural process in certain trees, which neutralizes and sta bilizes polluted soil. Phy-toremediation most often oc curs when pollution en-

ters the tree’s root zone with water and from there goes up through the tree trunk, out to branches and leaves. On its way, most contaminants are converted and neutralized, before it is released via the stomata – small ‘mouths’ in the leaves – as the tree tran-spires. In Enköping, Sweden, the method is used in a large scale project where willow trees clean the town’s waste water, after which they are cut down and used as bio-fuel in a local power plant.

SPOiLeD SOiL

Trees can drink tremendous amounts of water. On pol-luted sites trees can fix con-tamination in the soil, keep-ing it from entering la kes, oceans or drinking wa ter. Trees absorb the water con-taining contaminants, th u s preventing them from wash-ing out.

This method has been im-plemented with great success, for example, in our project in FredericiaC, where fishermen at the harbor feared that con-taminants from a former in-dustrial site would wash out and poison the ocean and the fish.

ThirSTy TreeS

You might have experienced on one hot summer’s day, leaving the chill of an air con-ditioned building and BAM! As soon as you hit the street it feels like you have walked into a wall of heat. The Urban Heat Island effect is a phenomenon that occurs in cities when build-ings and impervious surfaces are heated by the sun. The heat bounces back and forth between buildings and raises

the temperature of the entire space. Trees can help pre-vent UHI as the shade their crowns create, as well as the transpiration from their vital processes, lowers tempera-ture locally. This means more plea-sant cities and less need for expensive and CO2-emitting cooling of indoor areas, e.g. via air conditioning.

iT´S geTTing hOT in here

The Greenhouse Effect is a threat humanity can no long-er ignore. Increased emission of CO2 causes global warm-ing, flooding and extreme weather conditions. By means of photosyn-thesis, trees can reduce CO2 as they use sun and water to transform CO2 into glucose and oxygen.

Trees also store CO2 as they grow and can therefore be used as tools to fight the greenhouse effect. By plant-ing trees we can lower the level of CO2 in our atmos-phere and thereby reduce global warming.

heAL The wOrLD

Like an ‘Ocean view’, a loca-tion close to nature is a typi-cal buzz-phrase for real es-tate agents and tends to raise property prices. People wish to live in green surroundings so planting trees gene rally adds value way above the money it costs. For instance, in the Søn-der Boulevard area of Copen-hagen the introduction of

€2,4 million’s worth of vege-tation meant an increase in the overall value of the area of €47 million. Additionally, it has been demonstrated that sh opping districts with trees experien-ce considerably mo re sales than shopping districts with-out trees. Thus, trees are also good for economic growth.

A rOOM wiTh A view

Scientists have proven that a walk in the woods makes you healthier and promotes recovery. Forest visits have been proven to lower blood pressure, reduce levels of stress hormones, increase the ability to concentrate and re-duce ADHD in children. In Japan, ‘Shinrin yoku’ – forest bathing – has become a pop-ular movement. Each month, enthusiasts go on a field trip and camp in the woods. The health benefits last until the next trip.

However, it is not neces-sary to travel all the way to a forest in order to improve your well-being. A trip to the park or hugging a street tree helps too, and it has been proven that living near street trees reduces children’s risk of developing asthma. Ad-ditionally, people’s risk of becoming obese decreases by 40% in cities with an abun-dance of trees. Are you in the hos pi tal? Ask for a room with a green view and you will get better faster.

A wALk in The PArk

London used to be notori-ous for its thick smog, and still today you may have to re move black particles from your nostrils after a stroll around town. In Beijing, peo-ple wear masks because of the health risk posed by air pollution, but even in less ex-posed cities air pollution can be a discomfort. Rain can wash air pol-lution into the sewers – we all know the magic clean smell

after a downpour. However, what happens when it doesn’t rain? Trees can solve this problem for us. Leaves catch airborne pollution, the particles re st-ing on their surface waiting for the next shower, rather than floating in the air for us to breathe. More is less – that is; more trees mean less air pol-lution.

ScenT Of A cLeAn ciTy

Remember the feeling of picking an apple off your grandparents’ apple tree and eating it right away? Wouldn’t it be great to be able to do so on your way to work, or walking your kids home from kindergarden? Too bad you can’t eat fruit from city trees due to pollution – or can you?

Luckily, trees only absorb small amounts of soil con-taminants. The amount of air pollution on fruit is negligi-ble compared to the amount we receive just from breath-ing and can, by the way, be wiped off. Sensuous urban spaces with healthy fruits to satisfy your hunger are actu-ally within reach.

gOT The MUnchieS?

Many people object against trees in cities and elsewhere by reason of the expenses re-lated to maintenance. How-ever trees only require a lot of maintenance if you insist on pruning them. If they are left alone to grow they can, in fact, provide several benefits. An increase in the amount of leaves increases the effect of temperature regulation, rainwater absorption and air pollution control. When trees

defoliate, their leaves can be used as compost or simply be left on the ground for de-composition, where they will provide homes for insects and increase biodiversity, great ly benefiting the health of the entire ecosystem as well as the tree itself. By choosing the right type of tree from the start, concerning height and form, you´ve already saved on your operating budget.

nO SweAT

Long straight streets sur-rounded by buildings can create strong air currents and draughts, which can make staying in the streets both unpleasant and sometimes even dangerous when the wind is strong. Introducing trees into these spaces creates shel ter, improving mi croclimate s an d , in turn, im proving conditions for life between the buildings as the trees softly break the wind and dampen turbulence.

In the countryside the value of trees has long been known, and trees have been planted as windbreaks along fields to improve yields. But trees can also benefit your wallet when planted strategically close to your house. Here they can save you up to 25% on your elec-tricity bill, if you live in a windy spot and your house is poorly insulated.

gOne wiTh The winD

Trees are awesome – the scope of products containing ma terials derived from trees ranges from ping pong balls to building materials, all the way through to new medi-cine against cancer. You can harvest sap and nuts from growing trees and then build a chair or a hut from a fallen one. Imagine a life without the u t ilities extracted from

trees. No fruits in the grocery store. No chewing gum (as gum, xylitol and the wrapper stem from trees). No pencils, apples, latex gloves, toilet paper, tar, cider, golf tees, egg cartons, linoleum floors, totem poles... Quite boring, huh? Even this pamphlet is made out of trees. So, join the movement – love trees!

There´S nO enD TO The POSSiBiLiTieS!

In 1763, the British vicar and scientist Edward Stone, then suffering from fever, reaso-ned that because willows were abundant in swamps, they might have a treatment for fever, which also often occurs in swampy regions. He dried out a piece of bark and ate it. It had a healing ef-fect, and the discovery led to the development of Aspirin. The healing effect of trees can be explained by the long life that trees live in a fixed location. They must deal with

challenges locally and have, therefore, developed area-specific chemical responses – e.g. flavonoids and lignans – which are beneficial to hu-mans too. In pharmacies in industrialized countries 50% of the prescription medicine is already plant-based. Is it possible that city trees could develop similar survival mechanisms to sur-vive in the smog and crowds of the city and, thereby, pro-vide cures for diseases rela-ted to life in the city?

whAT if TreeS cAn SAve OUr LiveS?

Project Name_ Nature ParkClient_ Novo NordiskLocation_ Bagsværd, DenmarkRealization_ 2014Area_ 31 000 m2

Collaborators_ Henning Larsen Architects (Architect), Orbicon (Climate Adaption Engineer), Alectia (Engineer), Skælskør Anlægsgartnere (Landscape Contractor)

nOvO nOrDiSk nATUre PArk

In the city of Bagsværd to the north of Copenhagen, Novo Nordisk has erected its new corporate headquarters. The headquarters, which houses the company’s top management and 1,100 administrative staff, is located in a large, public nature park designed by SLA Architects.

The park’s overall design concept is founded on the teachings of great thinkers like Søren Kierkegaard and Friedrich Nietzsche who got their best ideas while walking. Modern research has shown that people become more informal, more relaxed and more creatively open minded when they are outside. This is especially true when they walk in nature that is wild, untamed and varied in its expression.

Every tree has been inspected and hand-picked by the designers in specially selected nurseries and composed in relation to their natural habitat, their shape, their volume and in relation to the local microclimate to maximize shelter for the users of the park and for the office buildings. The trees also help to absorb all rainwater that falls on site. Depressions are planted with alder trees and other water tolerant species in order to contribute to the park’s ambitious climate adaption design. As such, Novo

Nordisk Nature Park is the first park in Scandinavia with a 100 percent natural water balance. Thus all rainwater that falls in the area and on the buildings is collected and used for irrigation. Because of the landscape’s carefully designed topography and plantation the nature park can handle even torrential 100-year rainfall events without directing any water into the sewers.

The nature park itself uses a wide palette of native plants and holds over 1,000 new trees which over time will grow into clearly defined small ’forests’ and self-regulatory biotopes. The vegetation is designed to be wild and take care of itself, which allows the biotopes to evolve with natural succession and minimal care. Because of the stated desire to create maximum biodiversity in the park, several dead trees have been placed among the newly planted trees. Dead tree trunks have vital value for natural ecosystems as they are important habitats for beetles, caterpillars, mosses, etc. But they also provide the park with the smell of decay, the display of tree roots and a direct confrontation with the life and death within a natural ecosystem. It is a powerful exhibition of the full aesthetic feeling of nature.

PHOTOS:

1-2. Sigvart Verner3-5. Torben Petersen & SLA

wAnT TO knOw MOre?

DiD yOur cellar flOOD During THe laST clOuDburST?Embrén, B et al. (2009) Växtbäddar i Stockholms stad - En handbok

Nilsson, K et al. (2011) Forests, Trees and Human Health Peper, J. P et al. (2007) City of New York, New York. Municipal Forest Resource Analysis

Pauleit, S et al. (2009) Bytræer er med til at afbøde virkningerne af klimaæn-dringer

THe HOuSing MarkeT iS unDer PreSSure - HelP a birD TO neSTGeoffrey, H. D et al. (2013) The Relationship Between Trees and Human Health

Habitats ApS (2013) Biodiversitet i byer-forslag til synergi mellem biodiversitet og byudvikling

Karjalainen, E et al. (2009) Promoting human health through forests: overview and major changes

Nilsson, K et al. (2011) Forests, Trees and Human Health

Nordiska ministerrådet (2010) Nordens natur trender mot 2010

Robbins, J (2012) The man who planted trees. Lost groves, champion trees, and an urgent plan to save the planet

TreeS figHT criMeKuo, E. F (2003) The role of arboriculture in a healthy social ecology

Kuo et Sullivan (2001) Environment and crime in the inner city

SPOileD SOilRobbins, J (2012) The man who planted trees. Lost groves, champion trees, and an urgent plan to save the planet

Youarethecity (2011) Brownfields to Greenfields A Field Guide to Phytoremidation

iT´S geTTing HOT in HereKarjalainen, E et al. (2009) Promoting human health through forests: overview and major changes


Nowak, J. D et al. (2007) Assessing Urban Forest Effects and Values

Peper, J. P et al. (2007) City of New York, New York. Municipal Forest Resource Analysis

Wilson, G. W(2011) Constructed climates, a primer on urban environments

a rOOM wiTH a viewPanduro, E. T et Mortensen, E. M (2014) Økonomisk værdisætning af Københavns grønne områder


a walk in THe ParkEllaway, A et al. (2005) Graffiti, greenery, and obesity in adults- secondary analysis of European cross sectional survey

Karjalainen, E et al. (2009) Promoting human health through forests: overview and major changes

Park, B-J et al. (2009) The psychological effects of Shinrin-yoku (taking in the forest atmosphere or forest bathing) evidence from field experiments in 24 different forests across japan

Ulrich, S. Roger (1984) View through a window may influence recovery from surgery

ScenT Of a clean ciTyNilsson, K et al. (2011) Forests, Trees and Human Health



Having THe MuncHieS?Karjalainen, E et al. (2009) Promoting human health through forests: overview and major changes

Magid, J et Lekfeldt, S. D. J (2013) Vurdering af muligheder og begrænsninger for byhavebrug i København


Heal THe wOrlDNowak, J. D et al. (2007) Assessing Urban Forest Effects and Values



gOne wiTH THe winDHeisler,M. G (1986) Energy savings with trees

Houlberg, C (1979) Vind og læ i bebyggelser



wHaT if TreeS can Save Our liveS?Karjalainen, E et al. (2009) Promoting human health through forests: overview and major changes



This book is printed on recycled trees

why we love trees

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