Sweden protects old trees for biodiversity

Basal stem burning uses a ‘portable fire’, developed by Retrå Resource Operations, at the tree’s base to produce a partial burn scar. It prompts a resin-based defence, making wood highly resistant to rot.

The forestry sector is undergoing a shift in how it approaches environmental responsibility, moving from largely passive conservation to more active, hands-on methods. Leading this transition is Svenska Cellulosa Aktiebolaget (SCA), one of Europe’s largest private forest owners, which has significantly refined its conservation strategy in Sweden.

The company – a Swedish timber, pulp, and paper producer based in Sundsvall – is now placing greater emphasis on proactive ecological measures, grounded in the belief that active forest management can directly support ecological improvement and add value to traditional protection models.

For decades, conservation in Swedish forestry has relied mainly on setting aside areas from harvesting, either formally through nature reserves or through voluntary forest exclusions.

While these remain essential, SCA is now pursuing an integrated approach. It currently manages five large biodiversity parks that combine protected zones with active forestry methods intended to sustain natural, cultural, and social values.

This landscape-wide framework has created an ideal testing ground for more targeted conservation actions. Ola Kårén, Head of Forest Management at SCA, notes that this approach complements protected areas by allowing the company to take purposeful steps rather than only maintaining set-aside sites. He adds that timely intervention can provide nature with much-needed support and that this will be a greater focus going forward.

The aim is not only to safeguard existing features but to deliberately increase the number of old, biologically valuable trees and enhance the ecological quality of the surrounding forest.

Prominent methods

Two of the most prominent methods in this proactive strategy are “veteranisation” and basal stem burning. Both techniques accelerate aging in selected trees, encouraging features typically found in very old or naturally disturbed forests. They mimic the effects of low-intensity forest fires, once common in Sweden but now rare after a century of fire suppression.

‘Veteranisation’ involves creating controlled wounds on a living tree, often by removing a strip of bark from the trunk using a cutting tool or chainsaw. Extending from the base up to two metres and measuring 10-30 cm in width, this injury triggers a biological response in which the tree releases resin to protect the area.

The resin impregnates the wood with tar-like substances, slowing growth and forming denser, hardened “fatwood”, historically prized for tar production.

Basal stem burning uses a small, managed fire at the tree’s base to produce a partial burn scar, prompting a similar resin-based defence. The resulting wood becomes highly resistant to rot.

This is crucial for biodiversity: trees with these characteristics can survive for long periods and offer specialised habitats for wood-dwelling lichens, fungi and insects, including red-listed beetles that rely on fire-scarred, resin-rich wood.

Ola says that such trees play an important long-term role in supporting species dependent on these conditions and points out that fewer natural fires mean these features no longer appear on their own. He adds that this is where active forestry can compensate by creating more of these ecologically valuable trees.

SCA, among the earliest major forest companies to implement a comprehensive conservation framework, is now preparing to scale up these measures as part of routine practice. The goal is to coordinate them with existing harvesting operations to maximise ecological return. All harvesting areas already require the preservation of individual trees, clusters, and buffer zones.

For more information, write to:  info@sca.com.

 

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