As forests face increasing pressures from climate and disease, foresters are expanding the complexity and species mixes in the forests they nurture. Keen to explore what changes to the forest could mean for material supply, we take a look at how stakeholders in the timber supply chain might be impacted in the near to long-term. Do we need to rethink our approaches to materials and species to navigate this rapidly evolving landscape?

SPECIES

Responses to current and future timber species

At Pollmeier (Germany), a local abundance of material and observations of a growing demand for structural and engineered timber products has led to the development of BauBuche; laminated veneer lumber (LVL) made from beech trees sourced within 100km of the manufacturing facility. With high volumes of beech available in the region, but of a mixed quality, the need at Pollmeier was to develop a product that makes efficient use of local wood. A response to material availability and available timber properties.

To adapt to modern construction and the state of English forestry, Vastern Timber, a fourth-generation sawmill in the UK has invested to create high-value products from low-value, but readily available wood like ash, sycamore, and poplar. In 2022, Managing Director Tom Barnes invested in the UK’s first thermal modification plant to meet the demand for durable and dimensionally stable exterior joinery. At the same time as meeting a demand, the investment prioritised supply that would improve woodland management in the region.

“At the moment, all timber construction, all the timber construction standards, all the timber construction approvals, are all geared towards the use of softwood”

Professor Jan Knippers, ITKE Stuttgart

In the past, material specification would have been led by what was abundant in the area - timber, stone, clay etc., a material vernacular. Globalisation and centralisation of processing over the past century has led to more demand-led specification. In practice this translates as building designs being drawn up and materials being specified on the basis that any material can be procured that is right for the design. This is demand led procurement. From our conversations across the supply chain, it feels as though the start of a swing back has begun. A move to a more supply-led design paradigm that focuses more on material origin, availability, and sustainability.

At the edge of the Black Forest near Freiburg (Germany) we scrambled steeply after Florian Ruge, research assistant at the Forest Research Institute (FVA, Baden-Württemberg). Florian is trialling alternative tree species able to cope with a changing climate. In this region specifically, he is looking into species from Turkey, Greece, and Georgia.

Florian explains that 80-90% of the wood used in construction in the Black Forest region is spruce, Douglas fir, and pine. All of which are suffering from the impacts of climate change.

“The construction industry will have to adapt somewhat to these conditions. So we will lose softwood. Hardwood will increase in percentage terms. Foresters may also have to find other technological solutions to potentially process different conifers and more hardwood.”

Florian Ruge, FVA

HOOKE

ARCHITECTURAL ASSOCIATION, BEAMINSTER

PARK

“Some of the species, since they were planted in the 50s, we are realising that they are the wrong species for the site. So we're having to reconsider a more correct species for the site in terms of the location in the soil. But the other thing that has thrown us and has serious implications is climate change. So we've got to factor all of those things into our decision making”

Chris Sadd, Hooke Park

“What's striking today is that things are changing very fast, and foresters aren't used to things changing fast. You have to learn to observe the forest, how it reacts to a given level of harvesting, a given intensity of work or things like that. You have to learn to analyse, to sit in the forest, look at what's going on and try to understand what's going on.”

Jean-Jacques Bouteau, ONF

In the Architectural Association’s campus at Hooke Park we hear a similar story. Species diversification is being utilised to help the forest cope with a changing climate and reduce the risks of catastrophic forest collapse associated with a mix of just two or three species. The forester, Chris Sadd has worked to diversify from a largely spruce-beech mix to now seventeen and eventually over twenty tree species that will have both ecological and commercial functions in the forest.

Across Europe we see a comparable story, of increasing species and age-class complexity in the forests. Foresters trying to cope with the speed of changing growing conditions in a forest landscape accustomed to slow evolutions.

Eventually these changes will filter through to timber availability. We met with designers pushing the boundaries of species use, taking on the challenge of using timber with different structural and aesthetic characteristics in single buildings. Testing how a more complex palette of material can work together.

At the Ekkharthof Community Cantina an early decision was made to use ash. Not commonly used as a structural material in modern construction. For the community and architects involved it became a species to explore as a result of its abundance following the impact of ash dieback disease in the area. Here, where spruce or oak could have been used, the availability of ash combined with the inspiration of local glulam manufacturers has resulted in a building as inspiring to witness as it is to spend time in.

The project brought together local planners, architects, manufacturers and timber suppliers. It challenged the traditional supply-chain and broke from the easy and the routine.

“It becomes interesting when wood, with its specific abilities and also its weaknesses, is used in such a way that forms and constructions are created that, in the best case, are anchored in history and at the same time utilise the possibilities of timber construction technology. I think that's where it gets interesting for architecture”

Lukas Imhof, Lukas Imhof Architektur

“It's amazing when you have a 20-minute drive to the supplier to look at the beams and really know where they come from. That's really nice and also fits in with our philosophy at Ekkharthof.”

Melanie Bigliardi, Manager at Ekkharthof

LUGO

SPAIN

Venturing into an expanded palette of species was something we also saw in Lugo, Spain. While in Switzerland, the bioregional approach meant that design followed the species mix available from the forest. The Impulso Verde building in Lugo has a spruce CLT core, pine glulam, and Eucalyptus is used to create the gridshell roof. The timbers work in harmony within the building and mirror the mix of the surrounding forest species just as they do at Ekkharthof.

Watch here

“If we look at beech trunks today, we see that some of them are very, very crooked and have large knots. And if we now saw boards from it, there are many qualities that would not be usable for the load-bearing area.”

Patrik Rodlberger, Managing Director

Manufacturers can capitalise on the opportunity of finding long-term and structural uses for species not typically used and push the boundaries of what is possible. By focussing on the properties and characteristics that each species provide and finding a best use for them. Innovators like these lead a movement that will become more relevant as the species coming from the forest increase in their variety.

Those researching and testing products for future use do so in a bid to tackle pending multi-species forest complexity. At the Institute of Building Structures and Structural Design (ITKE, University of Stuttgart) Professor Jan Knippers is expanding the potential of hardwood and multi-species cross-laminated timber.

Dark Room, Hooke Park

Approaches like those of Ekkharthof and the radical work of the Architectural Association at Hooke Park perhaps point to a new vernacular. One that combines species availability and technology to make best use of a mixed species palette. Designers, led by supply potential with the best interests of the forests as a priority, and design; a response to the material available.

Alongside the complexities of growing multiple species and designing with multiple species is the difficulty of manufacturing components that employ a varied species palette that present differing properties.

The examples provided by manufacturers like Vastern Timber and Pollmeier demonstrate innovation based on species availability. Utilising material locally available that would otherwise likely find itself into lower value biomass markets.

Vatern Timber

Pollmeier

“It's about creating new sales markets for beech wood, which will be a more abundant resource in the future, and expanding the entire apparatus of standards, building inspections and approvals so that it also allows other tree species to be used in the future. It's not just about static use and also about availability.”

Professor Jan Knippers, ITKE Stuttgart

Professor Knippers' work has the potential to revolutionise how we view engineered timber that up to now, has always been fabricated from single species. The research team are using targeted reinforcements made of beech wood in highly stressed areas of spruce CLT panels where they meet supporting columns. This allows the possibility to construct differently, to design differently. Breaking work like this out of the lab as discussed in the Radical Realism film Jan echoes the sentiments felt at Ekkharthof. Jan notes how vital strengthening local value chains will be in making use of regionally available timber. Pushing it beyond just possible, and into probable.

Researchers and innovative manufacturers are not alone. Collaborations like the one between Critt Bois at the National School of Wood Technologies and Industries (Épinal), Weisrock (the largest manufacturer of glulam in France), and ONF (Office National de Forêts) demonstrate one of many routes to the real. Their project explores the production of hardwood glulam using lower quality timber. The timbers, typically destined for biomass, are transformed into high value structural applications. Currently this hinges on the research into glueing of new species and timbers with differing porosity.

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If you're inspired, challenged by, or curious about any of the themes or discussions the project touches on, we urge you to get in touch. This remains an ongoing conversation, not a static piece of work

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JOIN US AS WE EXPLORE THE FUTURE OF TIMBER

WHERE REALITY AND BOUNDARY-PUSHING COLLIDE

EXPLORING OPPORTUNITIES IN LOCALISED TIMBER SUPPLY CHAIN

QUESTIONING THE BOUNDARIES OF SUPPLY CHAIN DUTIES

RESPONSES TO CURRENT AND FUTURE TIMBER SPECIES

MONEY AND TREES

PROJECT SUMMARY

In Lugo, a major thread of research to utilise a larger palette of species was conducted in timber technologies that matched species properties. The coming together of researcher, manufacturer, and forester has been a critical factor in the success of these projects and perhaps points to a need for greater and closer academic/industry collaboration.