Industry Services
Industry Services
Dr Asselia Katenbayeva
Alliance for Sustainable Building Products
Are timber buildings helping or harming forest biodiversity? asks Asselia Katenbayeva. An ASBP project explores the impacts of timber sourcing and the challenge of measuring biodiversity. Why biodiversity matters—now more than ever.
One million species are edging toward extinction, the global science body IPBES warns. [1] Forests remain their main refuge: four-fifths of all land plants and animals live under a canopy. Woodlands stabilise soils, regulate water, and sequester carbon; their biological richness is therefore a silent buttress for every climate-mitigation plan.
The topic of biodiversity has never been as high as it is today. In England, Biodiversity Net Gain regulations now oblige most developments to deliver a 10% ecological uplift on site. Some companies also disclose nature related risks in supply chains under voluntary TNFD framework.[2] But how many consider whether a glulam beam CLT panel they specify helped or harmed the biodiversity of the forest it came from? Supply chain impacts remain a blind spot.
To gauge sentiment, the Alliance for Sustainable Building Products (ASBP) surveyed architects, engineers, developers, and other construction stakeholders; 46% thought that harvesting timber for construction has a negative impact on forest biodiversity and 26% were unsure. Barely one in five believed that timber harvesting could go hand-in-hand with thriving ecosystems.
Bridging that gap was the goal of IMPACTT, an 18-month ASBP-led initiative funded by Built by Nature and partnered with PEFC UK, Stora Enso, DoubleHelix, Woodknowledge Wales, Agrodome, Eurban, and other partners. The team traced the supply chains of 11 timber buildings—from forest to frame—and published the journeys as interactive maps (see ASBP Impactt [3]). The project also addressed common misconceptions around sourcing timber.
This view is outdated. While early commercial forests focused on monocultures and timber production only, modern sustainable forestry aims to integrate a balanced approach. The truth is, in the Anthropocene, we are beyond the idea of “just leave the forest alone”. Faced with rapid climate change, forests must be actively managed to curb pests and diseases, lessen fire risk, and buffer escalating climate impacts.
“The truth is, in the Anthropocene, we are beyond the idea of ‘just leave the forest alone’.”
“Measure it, manage it” sounds simple until you enter the woods. A review of 149 studies6 found 83 different sets of indicators used by academics for biodiversity in European forests, which fall into two groups:
No single, universally accepted forest biodiversity metrics exist. To capture varied perspectives, we convened a workshop with forest specialists, forest owners, leading academics, and eDNA analysis company.
A key finding is that forest age and structure significantly affect biodiversity levels. Younger plantations tend to have lower species diversity, but as they mature – developing varied tree heights, understory growth, and deadwood accumulation – they become increasingly valuable wildlife habitats. In many respects, habitat development in planted forests in Great Britain has occurred by accident rather than design, as a result of ‘normal’ (not sustainable) commercial forestry practice during the 20th century. With deliberate, well-managed practices, the potential is far greater.
Let’s refer to real examples of biodiversity in commercial forests. Kielder Forest, England’s largest planted estate, shelters roughly half of Britain’s endangered red squirrel population. Thetford Forest, on the border of Norfolk and Suffolk, is a Site of Special Scientific Interest supporting nightjar, goshawk, woodlark and other birds. Under deliberate management, a working forest can be a thriving living landscape.
UK-based NatureMetrics analyses forest soil and water, sequencing genetic fragments left by organisms. This method can reveal hundreds of taxa, including cryptic fungi and invertebrates, offering a rapid biodiversity snapshot. It cannot, however, establish a population size or confirm breeding success, but it widens the lens beyond what field observers can spot.
CLT producer and one of the world’s largest forest owners, Stora Enso, apply a range of methods for monitoring and managing biodiversity. They build digital twin simulations of its forests to test management options and use predictive modelling to pinpoint where certain species are likely to thrive. Where the company buys from third-party forests, it offers financial incentives for owners who exceed sustainable forestry certification targets.
Counting species alone does not tell the whole story. Chris Jones, silviculture specialist at Woodknowledge Wales, notes that each species should play a functional role—a “service” in the woodland ecosystem. For example, certain conifers, like spruce, are valuable for harvesting timber, while deep-rooted pine species offer wind resistance. Using an ecosystem services approach, different functions of the forest—timber, recreation, biodiversity, clean air—can be assigned value. In multifunctional forests, resilience to environmental change underpins the forest’s ability to support biodiversity.
Different trees also host very different lives. Dr Ruth Mitchell from James Hutton Institute referred to research comparing four UK staples: Scots pine, oak, ash, and Sitka spruce.7,8 Scots pine, a native tree, supports far richer biodiversity than Sitka. However, simply counting the species is not enough; it is crucial to understand the roles these species play within the forest ecosystem. Likewise, tree species diversity alone is not sufficient for promoting biodiversity; forest managers must also consider how forests are structured and managed.
“If we want to determine the impact,” noted Prof. John Healey of Bangor University, “how do we decide what to compare it against?” Should a production forest be compared with an unharvested reserve, an area managed exclusively for biodiversity, or another production forest managed differently? The choice of counterfactual can reverse conclusions. Biodiversity in forests is also influenced by complex variables such as management practices, geographic location, and the forest growth cycle. Furthermore, the metrics must consider not only species numbers but also conservation values. For example, a forest with fewer species might actually host a higher proportion of endangered animals.
Borrowing concepts from carbon accounting helps:
Switching the narrative from ‘do no harm’ to ‘achieve net benefit’ is crucial.
Every joist, beam and panel that rises inside a building begins life in a living forest. If we want architecture to serve the planet, the ledger must capture the full impact of sourcing materials. Specifying timber is not merely a procurement decision; it is a vote for the forest’s future. We should raise the bar and ask not only about cost and thermal performance—or even how many tonnes of CO2 were sequestered and locked into the building— but also: What did the forest of origin gain?
