AR Ecologies: building with trees

Completing the tree-filled trilogy, the AR turns to focus on timber, our fundamental link between trees and architecture. Timber, especially mass timber - is seen to be one of the most ecologically sustainable building materials and an obvious alternative in construction. But when a virtuous material is used to replicate capitalist models, the result can exacerbate, rather than counter the climate catastrophe. Scientist Suzanne Simard, architecture historian Erin Putalik and engineer Maria Smith share their projects, voices and perspectives on how we see, build and ultimately grow trees to operate in the same world that preserves and produces this essential building block of our existence. Hosted by Sabrina Syed.

AR Ecologies, a podcast by The Architectural Review, explores the tension between architecture and ecology through critical positions. Instead of standalone interviews, each episode weaves curious and critical voices together to meet, discuss and give space to perspectives outside an architectural orbit. The first series revolves around trees, an audio counterpart to the AR October 2021 issue, available now.

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Bibliography

Finding The Mother Tree (2021), Suzanne Simard
The Mother Tree Project, long-term research experiment led by Suzanne Simard
Wood stock: the many lives of lumber, AR June 2021, Erin Putalik and Jane Mah Hutton
Urban lumber: timelines of street trees, AR October 2021, Erin Putalik
The wood-products industry is undergoing root-and-branch change, The Economist May 2021
Mass Timber in the age of mass extinction, Failed Architecture March 2021, Alexander Hadley
Cop26 World Leaders Summit- Presidency Summary, published online 3 November 2021
Mass timber solutions for eight story mixed-use buildings: A comparative study of GHG emissions, Buro Happold report June 2021

Transcript

AR: Timber is the fundamental link between trees and architecture. When trees are worth more dead than alive, we’re turning to look at their identity in the economy that fuels their transformation. This episode is all about how we transform forests into timber, and ultimately how we can grow forests to operate in the same world that preserves and produces this essential building block of our existence.

Timber, especially mass timber - is seen to be one of the most ecologically sustainable building materials and an obvious alternative in construction. Every day, millions of trees are transformed into the building blocks of our architectures, from DIY jobs to large buildings, aimed at minimizing their carbon footprints. In the past 12 months demand for timber rocketed – the DIY boom during pandemic causing shortages in lumber, especially in the global north like US and Europe. But it’s not just this past year. Global exports of forest products (including sawn wood, pulp, paper) grew by 68% between 2000-2019 ($244bn). There is an upwards pattern with our consumption of timber. The transformation of forests into timber, of trees from being alive to being a crop - farms informs a historically powerful and complex global economy.

When a virtuous material is used to replicate capitalist models, the result can exacerbate, rather than counter the climate catastrophe. It’s a strange paradox that we live in when you look at it through this lens. I want to be clear here and say that this isn’t a thread where we argue against using timber in the first place, but it’s important that as designers, we see the broader picture we’re working in, and the runaway train effect that can happen if timber is not managed carefully when it comes to turning forests into products.

Suzanne Simard: As soon as you clear cut a forest, you know, those trees go off into different products. But scientists have estimated that about 65% of that above-ground portion of the ecosystem is immediately lost to the atmosphere because it's converted to short term products.

AR: Suzanne Simard, forest ecologist, scientist and author took me through a real-world example of how the desire to decarbonise our energy sector (which is deeply important and should be done by every country) isn’t as straightforward as it seems when you look at it through global trade. It can turn into a murky series of unfortunate events when run unchecked. This is a short story connecting the forests in Canada, where she works, to the UK.

Suzanne Simard: One of those solutions in the UK has been to convert energy systems from fossil fuels to alternatives. And so one of that is through bioproduct - bioproducts includes things like burning biomass. A market has been developed in the UK that is fed by British Columbia - Alberta and Canadian forests - where they're taking fibre from our forests and converting them to wood pellets and shipping them off to the UK to burn in wood stoves so that you can get off fossil fuels...

AR: From 2022, wood burning stoves sold in the UK must meet these "ecodesign standards" by law, hence the new market for wood pellets, which substitutes coal. Sounds pretty solid, right? But speak to a scientist and cracks emerge when the maths - in this case, the full carbon analysis, balancing out what energy and emissions are gained and lost - gets done.

Suzanne Simard: When people do the full carbon analysis and energy analysis, it doesn't make any sense. We're not just taking extra fibre from clear cuts, companies are also going into ecosystems that are full of carbon in soils, maybe a bog ecosystem. They are literally going in and planning to harvest Boreal forests where the trees don't grow very tall but below ground there's this rich, rich carbon storage. So converting those to wood pellets and then sending them to the UK so you can get off fossil fuels? Well, those soils (at the same time as we're clearing the forest) start to mineralise, and the CO2 in the soil, which is a huge sink, ends up going up to the atmosphere. And so this is actually going to accelerate this practice that, when you add up all the numbers makes no sense, right?

AR: One of the biggest misconceptions about using trees and forests is the lack of regard for soil that holds vast stores of carbon. Ironically, the peatlands Suzanne describes in Canada that are being extracted from also exist in the UK and are known to store 20 times more carbon than in the entirety of the UK's forest biomass. So, importing it from another country to fulfil a new "ecodesign standard" sounds as backwards as it looks.

Suzanne Simard: We have to do the math, right? And we haven't been disciplined enough internationally to do the proper maths (or scientists are doing it). But the industry, in the meantime, is getting going. We're better off to continue burning fossil fuels in the UK than taking the Boreal forest of Canada, turning them into wood pellets, shipping them to the UK and burning them.

AR: This runaway train effect can risk undermining the planet's natural carbon reserves were looking to protect in another part of the world. The transformation of forests to forest products, especially in architecture, is one of the most complex processes in the world. Bridging the non-human with the human through materials.

Erin Putalik: Ecological justice is - especially in the context of materials - taking into account the biggest possible picture of the implications of any material use in terms of time and geography.

AR: Erin Putalik is an architectural historian at the University of Virginia, whose work revolves around ideas of what wood is or should be, and the history of how forests are used and considered in architectural frameworks.

Erin Putalik: I came from practice and was really invested in using renewable or rapidly renewable materials. But the idea of what that has even meant through time didn't really sink in until I started to dig into the history of how we've valued and depicted forests as a profession. Maybe one way to talk about it is a kind of long history of ideas about renewable materials - because a lot of those emerged in wood, but they extend to many of the materials that we use now. A lot of them rely on constructions of the nature that they come from or support.

AR: When we're talking about timber we often stay in the present, especially now. But how has our perception of timber evolved and how does it inform the way we build and grow trees? One way of documenting this in architecture that Erin does is looking at ads from the 20th century, especially ones in America, sort of like a Mad Men-esque investigation into how forestry companies chose to market timber.

Erin Putalik: One of my favourite ones actually is from 1950. It's for Weyerhaeuser Timber Company, and it shows the scene of a rolling mountain - looks very much like the Pacific Northwest. But all of the trees are young, and they're all evenly aged and evenly spaced, and the trees are kind of surrounding this rock outcropping and on the rock outcropping is this family of raccoons clustered together and also looking off into the distance. And one of the raccoons is swiping a dragonfly, and as his paw swipes, it points at a clear-cut patch in the far distance of this productively managed forest. And so the argument is so essential and powerful, which is that this is still a landscape that still supports the kind of wild nature that we value as a nation. But yet it's also very intensively designed and managed to produce the things that you need. Opposite that raccoon tableau are all of the things that come from these woods, which are, you know, sheets and beams and trusses and all different forms of timber and packaging (packaging was a huge use of wood and still) so it is this, like: "we're working with this wild nature in a kind of co-productive and reciprocal way in order to take what we need without taking everything."

AR: Ads are important to this story and understanding timber in contemporary times because the capture a quality that is intangible: they’re all about nuance. Timber, and all forest products are presented as materials that act like a magic bullet, a straightforward solution by the fact that it is a virtuous material – when economically and historically, the story is far more complex. Understanding the terms in how we see timber as virtuous is critical to a better understanding of its place in architecture today.

Erin Putalik: They've been really informative and interesting because you see the kind of nuances of the rhetoric used to convince architects that wood is both the appropriate building material to their technological and aesthetic moment, but also the ecologically appropriate choice given the state of the forest. The overarching narrative would be: the shift from a mindset of inexhaustibility and plenitude to an increasing interest in conserving certain forests, the kind of primaeval or virgin forests at the expense of harvesting others. And so that's a shift from an extractive "mining" mentality (the kind of timber mining was a kind of phrase that came up a lot in the 1920s and 30s) versus "timber cropping". So treating timber as a renewable resource and becoming comfortable with "lumber" that had been grown in the lifetimes of those consuming it, which meant that it was smaller pieces of wood, faster growing typically and had come from a managed forest.

AR: This idea of a managed forest - of delineating lumber from trees is something I want to come back to because there's so much to be said about it (especially when it comes to this idea of growing timber in a way that's also ecological). But there's another point Erin picks up on towards the end of this thread of growing smaller trees and smaller pieces of wood: that of scale. Historically, timber has always seen to be a very domestic material...

Erin Putalik: ...Building with timber already has this kind of toehold in acceptability because, you know, humans have been building with timber for millennia. And there's a kind of sense that it's deeply appropriate to domestic-scale construction because we understand the lifecycle of that scale or that type of construction to be a little bit quicker.

AR: Mass timber, also known as engineered timber, is an umbrella term that describes a range of wood products like glulam beams and cross-laminated timber. It basically scales up what we can build with. So instead of steel or concrete, primary loadbearing structures are made out of solid or engineered wood. And that's what we call a "mass timber" building. Being able to build larger structures with mass timber like skyscrapers and stadiums means that bigger chunks of our cities could emit less carbon through their construction. France is a great example of this going into policy, where construction of all new public buildings by the state have to be composed of at least 50% timber or biobased materials by 2022. So can mass timber be used in a monumental way?

Erin Putalik: Mass timber proposes use at a monumental scale even as it is obviously participant in a much more rapid cycle of obsolescence. We think of monumental scale architecture as kind of fundamentally mineral; I think that's one of the hurdles in terms of public acceptance that mass timber is meeting, because we've never, you know, you could say most cultures have never had an issue of building with timber and lumber. It's automatically been part of some sort of deep cultural acceptance and knowledge. But when you're shifting scale like this, it is proposing something for which we don't have any existing reference points or we don't have many. And so if we had a lot of examples of massive timber architecture from antiquity that were readily available to the popular imagination, I think the safety anxieties would be a lot less intense.

AR: How does our perception of timber - that we know is very elastic - change in terms of its trajectory for architects, but also for people viewing the industry from the outside?

Maria Smith: It's been very difficult within the timber industry over the last few years. On the one hand, a huge drive to try to use timber as the sort of the first choice of material if you want to create a sustainable building. But then, on the other hand, there are many challenges around regulation in terms of fire acoustics, water damage while projects are on site and so on...

AR: That voice explaining the uptake in timber industry and its challenges is Maria Smith. After becoming an architect in the UK and frustrated with the limitations they found in terms of tackling the climate crisis in practice, they decided to pursue engineering at London's Open University...

Maria Smith: ...I didn't have the knowledge and the skills to really delve deeply into the stuff of buildings that I think makes a real difference in terms of things like tackling the climate emergency. I wanted that knowledge and I felt locked out of it, so I basically found out "if you want to do this, you have to start from the beginning. You have to do your three full years, get an engineering degree." But by that point, I felt like I'm committed now. So I did it! It was brilliant. It was so intense. But the Open University is amazing and I'm so proud to be a graduate of the Open University. I think it's an incredible institution that just opens up education in a different way.

AR: Maria is now head of sustainability at Bureau Happold and currently pursuing multiple urban projects that revolve around using timber. One of them is a design for a model timber building that seeks to confront the material head on in its entirety and demonstrate how it can be a reliable material when used throughout construction...

Maria Smith: It's working out all of the details, it's working out the structural system. It's making sure that there is a template there that can then be applied with confidence. So the idea is that we can demonstrate that this is technically possible and that these technically possible things are also meeting regulations and so on.

AR: When it comes to making a natural material work in architecture, regulations are often the biggest obstacle to overcome...

Maria Smith: ...There are a lot of concerns around fire safety. Obviously, fire safety is absolutely something to be taken incredibly seriously. But it also is technically resolvable. You can absolutely create a firesafe timber building, absolutely can do that. The other concerns are around acoustics, so acoustic separation. When you are creating buildings out of concrete, for example, the mass of that concrete is helping you create acoustic separation between different small spaces and so on. And so when you have timber construction, you need to find other ways to do that, which is again completely possible but we want to demonstrate the ways in which you can do that. But yes, this is a concern, but also there are solutions. The other thing is, you know, for example, around water - obviously when you're building a timber building, there is a time when that timber is exposed to the elements and so you have to just design and factor those things in its design. It's all solvable, we just need to demonstrate that this is how it's solvable. And there are loads of major case studies that have demonstrated this but with with the model building idea, the idea is just to put all of these things in one clear kind of template that could be reconfigured and adapted to many, many different scenarios, but show that this is possible.

AR: So hesitations about mass timber construction as something that is unstable, unviable or unreliable have been debunked time and time again, not only through templates like the one Maria's team have developed, but through built projects. But to transition to it confidently, they explained two key factors that need to work in tandem to make it happen: the potential of replicating ideas over and over again until they can proliferate and the broader policy changes that need to happen in order to achieve carbon targets that governments promise to reach.

Maria Smith: The big problem, I think, is a question of scale and replicability. It's easy to read Braiding Sweetgrass and think, "wow, this is amazing, of course it changes everything." But then you go to your desk on Monday morning and while your mindset has shifted a little bit the amount that you can actually change your practice is quite limited by the framework of the economy and the systems that we're set with it. And then you, you find yourself in just specifying another steel beam, it's like "mmm, this doesn't feel right. This isn't quite it!" and so the journey that we have to take to communicate and to figure out how to how to incorporate all of these different technologies - that's the big challenge. You know, more broadly, we as an industry need to be working together to show our capability, to reinforce our capability to clients as a whole. But the other thing that I think is helping move things is that many, many clients are creating very ambitious commitments. And in order to meet those commitments, we need to make use of materials and technologies such as timber in order for them to achieve those. Making use of timber is one of the key ways that we can reduce the embodied carbon and whole-life carbon a projects. You're not going to be able to achieve a lot of those, a lot of those targets that they've set. And I mean, Lendlease, for example, as well, you know, have set insanely, very, very fantastically ambitious targets of absolute zero by 2040! There's no way you're going to achieve that without changing the way that we build, so we have to re-question and reformulate those type of design practises and mass timber is an absolutely critical part of that shift.

AR: When a natural material needs to behave in ways against what it's prone to do in nature - what it's prone to do ecologically, like absorb water, for example - this transition is something that makes the non-human human. It makes something natural, become inherently anthropocentric. And it's happening economically, chemically and through all the intangible ways in how we perceive "wood" as wood.

Maria Smith: Well, I'm really interested in is how the ideas of beauty and architecture and design justification, methods, systems, what it means to be rigorous - those things have to shift too...

Erin Putalik: ...I wish architects knew that you didn't always have to specify the best. That allowing irregularity or defects, or visual or aesthetic defects was a kind of wonderful way to incorporate the diverse lives of trees in a forest into the final product.

AR: The transformation from tree to timber inform what we see as acceptable when it comes to our role in maintaining it. Because all the ways that we've improved timber production has allowed us to create regularity and predictability in a material that is implicitly irregular. I asked Erin about how we perceive treated wood often used across timber buildings, including mass timber buildings. These are all considered virtuous materials (at least more than concrete, cement or steel in terms of their embodied carbon). In the world of particleboard, plywood, OSB - all the elements that come essentially from the same forest that turn into these forest products - to what extent are these still wood? And as a result, are they still virtuous?

Erin Putalik: When your OSB siding bulges or becomes waterlogged or full of mildew, when you're a particleboard shelves start to delaminate or bend...and also when your pressure-treated deck starts to look too old...there's very little that you're invited to do to help it get back to how it was because of how thoroughly transformed those woods are. They kind of dissuade participation, you could say. They kind of keep one at a distance - you're not sure if you should sand your pressure treated because you're not sure if the wood contains something that would then be released in the sawdust that might make you sick. These words that have been kind of chemically and physically transformed to the degree that we no longer really know how to interact with them, how to fix them, how to take care of them - on those terms, which are really important in terms of living with the material - on those terms, they're really not "wood" anymore. You know, we're not sure if sanding them will make us sick, if we don't know how to patch it or glue it, if it's sort of just fraying and decomposing right in front of us - on many of the fundamental ways that have made "experientially" wood in terms of our ability to work with it and live with it and fix it and repair it - those have kind of categorically changed...

AR: So envisioning a built environment led and filled by wood, by timber, also means acknowledging the full spectrum of materials that emerge out of it - this intention to be sustainable fuelled by an economy built by forests. Acknowledging what we are prepared to accept economically, structurally, but also aesthetically and culturally, is a multi-layered conversation when it comes to using timber. And we're only just scratching the surface of it. These are the conversations that often don't make press releases, or the goals set in summits or the details that get skipped out in timber when it's promoted as their material of choice in architecture (and deservedly so) to design ecologically. I always come back to this thought Erin shared, and mass timber that perfectly sums it up:

Erin Putalik: I think that number is great, just to be perfectly clear. I'm really excited about it, but I think we need to be more reflective and think more carefully about how we define what is ethical building and what is a kind of environmentally virtuous building material. Not to claim that mass timber is not, but to think about the terms on which we claim that it is.

Maria Smith: Creating a built environment is very much a team sport. It involves so many different actors. There's going to have to be little shifts from all sides. I'm optimistic. I think that will happen. I think projects like the new model building is is one good step, but that has to be met with the insurers thinking again and the clients thinking again. But I think there are so many drivers and the awareness generally about the climate and biodiversity emergencies mean that the context is there. It's just that by working together, that egotistical thinking [to] more ecologically, that rather than coming into a system and thinking, "oh, what can I get out of this" to "how can I fit into this?" That shift in mentality that is so slowly happening means that we will be looking for different solutions.

AR: I want to continue by going back to where we began. By this I mean completing our timber episode by going back to the origin of our series - and that's planting trees. Looking at the seed that makes the material. Looking to how the very forests that generate our supply of mass timber are considered.

Erin Putalik: I think if we were able to talk more frankly and less romantically about the function of forests in our societies and not just our ancient romantic visions of lush greenery, but actually productive croplike heavily managed forests - and be more conscious about the fact that these take up now massive areas of our globe and need to be treated as landscapes that should be managed in the context of both fair labour and hopefully some type of ecological richness - that would really help the kind of mystique surrounding mass timber. When you look at a lot of the literature of mass timber, it doesn't really show you the types of forests that material actually comes from. It shows you like national parks: the forests that we get to "save" basically by using this wood that's produced in a much more regular manner.

AR: There's a clear separation between the forests chosen as the ones we get to save and the forests that we plant specifically to supply our timber economy. They're both two roads to operating ecologically in architecture and I think it would be refreshing to talk about plantation forests - the ones that we plant for the timber that we need - as something besides a dirty secret or something that's totally separate to saving the world's biodiversity and sustaining it.

Erin Putalik: The thing that's amazing about mass timber is how omnivorous it is in terms of the material that you can use to fabricate it with: invasive species, if you get past killed trees quickly enough - my understanding is that you can incorporate those. And so I think in the same way that material advertising directed architects in the 20...imagine that they needed to know fundamentals of wood species, properties and the kind of ecological implications of using one species over another. I think that would be really nice to know now. The kind of more nuanced, more developed, more honest accounting of the landscapes that produce these materials so that we could take account of them as something that is covering increasingly large portions of the globe. Or a landscape that should be held accountable to the ecological hype surrounding the material that it produces.

AR: Throughout this series, we've spoken about trees and forests across different lenses: forests as living networks that operate almost like a giant brain, trees as special agents, the power and politics of land that forests rest on and the human lives that are at stake. Forests as heritage or as rejections of colonial views on architecture. We've also looked at timber in a broader spectrum as a material, as part of a capitalist economy, as a product of our own perceptions on what makes a natural material virtuous. One of the last big questions connecting the gap between timber and forests remains to be asked: what can forests teach us about growing timber ecologically?

Maria Smith: One of the reasons I was so excited when you told me about this podcast and focusing on forests is: yes, we need to incorporate timber into construction and timber technologies into our construction and built environment industry. But also - we need to learn from forests. Forests know what that doing. Forests are an amazing ecosystem, network, ways of creating balance between different elements of an ecosystem...

Suzanne Simard: ...People have always been part of forests and we've been working was forests forever. The Aboriginal people of Canada, for example, burned the undergrowth around their communities so that there wouldn't be so much risk of fire. And so working with the forests, we have a long, long, long history of it. And logging is a different form, but it's another form of management. You know, "management" is also a term that's not used in Aboriginal languages (this idea of) "working with nature." So "management" is very much a western construct!

Maria Smith: We need to not only take raw material out of forests and incorporate it into our systems. We need to actually work with forests and have a - I don't know - is it too much to say a genuine knowledge exchange with forests to understand how can we create habitats for humans and non-humans alike that are genuinely sustainable, genuinely working within planetary boundaries and ecosystems and so on, and forests know how to do that! They're both a resource but they're also a huge source of knowledge resource as well, and we have to humbly and respectfully study them and understand them.

AR: The last bit of knowledge exchange I want to share goes back to bridging or conversations on ecology with science. It's an ongoing project of Suzanne's, whose work revolves around how trees connect with each other and what she calls her biggest and most complex project to date. When academics were not convinced that forests had networks at the scale Suzanne had been researching. She turned towards a very architectural tool: maps, in a Douglas fir forest prized for its timber.

Suzanne Simard: We need to map what these networks look like in a forest so we can show people. So I got a graduate student, Kevin Beiler, and he spent five years of his life making maps of what these networks looked like in a Douglas fir forest - to try to use structure of that forest, which was highly complex and stratified in age and size - to infer from that process, processes of what did these networks mean? We found every tree is connected to every other tree through various avenues and what emerged from the map was that the old trees, the big old trees were the most highly connected

AR: ...in this map, this biological master plan as it were - these older trees act as "hubs"...

Suzanne Simard: ...so they're like central points. They have huge root systems, many points of contact, huge crowns with photosynthesis, and so they connect much more frequently with other trees than a smaller tree would - because just the virtue of physics alone!

AR: Suzanne started asking: what do these old trees do in our forests? Apart from being an enormous carbon sink, she noticed that younger trees would happily regenerate under the canopies of these older trees instead of being artificially planted like in a plantation - almost like they were plugging into an older-than-us-energy supply of knowledge within the networks of existing trees.

Suzanne Simard: And so I started doing a bunch of experiments with my students of putting seed out, and we would do these experiments where they were allowed to connect with the old trees and not connect with the old trees. Eventually, we also looked at seedlings that were the relatives of the old trees versus strangers of the old trees. And we found that, you know, that the regeneration, the survival of those seedlings and the growth depended - it was interdependent with their ability to connect with the old trees, and that these trees could recognise and favour which ones were their own offspring, their own kin. And that led us to calling these "mother trees" which is really a colloquial name because these trees actually have mothers and fathers in them. But I picked that name because it evokes in us an understanding immediately, and I've gotten a lot of flack for that name in the scientific world! But I think it's been important for an understanding among people, because we all know what mothering is, what nurturing is, that this is an essential collaborative part of nature. So that's where the origin of that term Mother Tree is. That's what they are. They're just the biggest, oldest trees in the forest that connect. They're the connectors, they're the nucleus of the forest.

AR: Mother Trees: the oldest, largest trees in our forests may be the key in managing a forest to both thrive and potentially grow trees for our timber, that is deeply ecological. Suzanne calls it the Mother Tree Project, and this heartbeat of knowledge exchange may answer the question on how forests can actually coexist with our need for timber rather than be considered separate entities.

Suzanne Simard: I started it in 2015. I was 55 years old at the time so I’m getting near the end of my career, why would I start a big project like that now? But it really it was a natural progression. I wanted to take my basic research on connection in forests and make an application to how we would treat our forests in the future, how to foster resilient forests as climate changes. That was the objective of the project. It's a 900-kilometre climate gradient, so it's an area that's like the size of Sweden. We have 9 forests replicated three times each. So 27 forests across nine climatic regions with the idea that in hot dry areas, that compared to the wet cool areas at the other end of our gradient that as climate changes, those wetter forests will start to become and look like the drier ones. And then we can make intelligent decisions and see what to do. And we're using modelling at the same time to project of the future. So we're doing a full court press on this! Within those climate gradients where we're saving or leaving, we're doing some harvesting and comparing clear-cutting with leaving Mother Trees in different patterns and different amounts, leaving clumps of trees in small patches and then larger patches, and comparing them to intact forests and looking at the effects of these on carbon budgets, on biodiversity and on resilience or regenerative capacity of the forest and then a whole suite of other things associated with those.

AR: The velocity of climate change is about a thousand times faster than the speed at which trees can migrate or adapt. So that means trees are going to keep dying unless we intervene. I'm recording this off the back of the COP 26 Global Climate Summit happening in Glasgow and just recently world leaders pledge to end global deforestation by 2030, the first major deal agreed out of this event. Suzanne believes our relationship to managing forests as they stand can change for the better. And interestingly, the trees that she works with - Douglas fir - are a species that not only benefit from this experiment, but also fuel our timber economy in architecture. That's why this project, which has its roots in science, connects to timber, connects to architecture, connects to everything.

Suzanne Simard: ...but what we can do as humans is we can move trees. We can move genotypes. We can make for Douglas fir, for example, it occurs from Mexico up to the middle of British Columbia, it's a huge climatic gradient. And so we can move these local populations to cooler areas, it will become warmer in the future so that they're are adapted. So what we're finding - here, I'll give you a few results: is that when we leave these old trees, these migrated genotypes do better. They survive about 30% better. And so that just shows you - like the connection - they need to be migrated into fairly healthy ecosystems with old trees to nurture them along. They can link into the networks of these old trees. They benefit from the shade, the protection that the community that already exists there, that will bring them along. They're migrants. They need to be brought into the community and embraced just like in human communities...

Erin Putalik: Forests are communities. I think no matter whether they're spontaneously arising or planted, I think they enable our communities and they are their own communities.

Erin Putalik: ...and when we have these old trees there and these seedlings are doing better and there's natural regeneration, we also see the carbon pools. We also save biodiversity. But if we clear cut them, we lose. We lose so much. So that is what the project is about. It's a 100-year project. I'm the leader, but it's really run by the students - there's about 20 students out there in the forest today, doing all the little measurements of the soil of the forest for the trees, documenting everything and they're the engines that are driving this forward.

Erin Putalik: I think ecological knowledge is something that we've lost long ago and are just trying to reconstruct now. And we're having to find out as our kind of basic understanding of what ecology is, is radically transforming.

AR: This trilogy of episodes opened with the forest made by design - that of photographer and ecologist Sebastião Salgado. His project was about restoring what was lost in his own hometown. It only made sense to end with another forest project by design, this one looking to negotiate how we can live together. The identity of forests, of bridging the non-human world to the human with the creation of timber is a profound, multi-layered process that reverberates across how we see and use not only the material, but fundamentally how we approach trees. And we have the knowledge to protect and advocate for these trees as architects. We're not passive actors in this. I hope this episode showed the in-between spaces, the in-between conversations in which we can dwell in when it comes to trees and timber and how that informs our architectural ecologies.

Maria Smith: Something that makes me optimistic is that nobody hates forests, right!? I mean, some people might have terrible allergies and things like that, but it's an absolute joy and pleasure being surrounded by trees, and that's something that's very, very, very, very shared.

Erin Putalik: Our systems are built as complex systems, and that means that they heal, they regenerate. They build. They're resilient. That's how, you know, natural systems just evolved that way. They evolved to work that way.

Maria Smith: That gives us a really good basis groundwork on which to build and the process of shifting to a more regenerative environment for humans and non-humans alike is a reconnection with that joy rather than a starting from scratch.

Maria Smith: We have enough knowledge to do this in a way that is resilient and sustainable. We do have that knowledge - we can do this! We can leave old trees and still take out trees to harvest, to provide for our buildings and our needs. But we need to be more careful about this, more knowledgeable, not so exploitive. We've let exploitation govern our economic system, govern how we do it, and it's not going to work for us. We need to be holistic about this, understanding the ecosystems, the social needs and the economy as well, all as one. But there are definitely solutions out there. We just need to implement them and be flexible and adaptable.

AR: We've heard different definitions of what ecological knowledge is, and I've been reflecting on what it means for me throughout making this podcast, and I think that ecological knowledge ultimately is a state of being. It's an openness to embrace worlds that aren't human to live together through communities and disciplines out of our orbits. Ecological knowledge is indigenous knowledge. It's fundamentally holistic. It rejects colonial definitions and has no distinction between us and the "other". And ecological knowledge is generous. It's ever expanding. In terms of forests, what better teachers do we have than some of the oldest beings on this planet?

Erin Putalik: You know, a tree is this really crucial organism, but what humans have thought a tree is, is something that has been massively unstable and transformed in a really interesting way.