Unveiling the Carbon Powerhouses: Lund University's Groundbreaking Findings

A landmark study from Lund University has revealed that Sweden's old-growth natural forests, often referred to as primary forests, store a staggering 83% more carbon than intensively managed woodlands. This discovery, detailed in the prestigious journal Science, challenges long-held assumptions about forest carbon dynamics and underscores the critical role of untouched ecosystems in combating climate change. Led by postdoctoral researcher Didac Pascual and senior lecturer Anders Ahlström, the research quantifies how these ancient boreal stands—dominated by spruce, pine, and birch—act as superior carbon sinks compared to the even-aged plantations that dominate modern Swedish forestry.

Sweden's boreal forests cover about 69% of the country's land area, making them a linchpin in Europe's carbon balance. Yet, rapid industrialization since the mid-20th century has transformed vast swathes into production forests through clear-cutting and replanting. The study shows primary forests hold 78-89% more carbon across living trees, dead wood, and soil to 60 cm depth, with soils alone matching the total ecosystem carbon of managed forests.

Decoding the Methodology: A Decade of Rigorous Fieldwork

The research spanned nearly ten years, beginning with the creation of the first national map of Sweden's primary forests—remnants minimally impacted by human activity. Researchers scoured remote, low-productivity sites overlooked by agriculture and logging, conducting inventories at over 200 plots. They dug nearly 220 soil pits up to one meter deep, analyzing samples in labs for carbon content at various depths. Tree and dead wood measurements drew from field data, while managed forest benchmarks came from Sweden's National Forest Inventory (NFI) and National Forest Soil Inventory (NFSI).

To ensure robustness, multiple statistical methods—including random forests modeling and bootstrap confidence intervals—were employed. The team even accounted for carbon in harvested wood products, estimating short-lived uses like paper (25%) and bioenergy (50%) versus long-lived construction timber (25%). This comprehensive approach revealed differences 2.7 to 8 times larger than prior global estimates.

Breaking Down the Numbers: Trees, Dead Wood, and Soil Supremacy

Primary forests excel across compartments: 87% more carbon in living trees due to larger, older individuals; 334% more in dead wood, forming a natural legacy pool; and 68% more in soils to 60 cm. Remarkably, soil carbon in old-growth forests—about 64% of total ecosystem carbon in the top meter—equals the combined trees, dead wood, and soil in managed stands. Overall land carbon storage (including products) favors primaries by ~72% (70-74% range), or 9.9 kg C per square meter more.

This gap equates to 211 years of Sweden's current fossil CO₂ emissions or 1.5 times all since 1834, highlighting irreversible losses from conversion.

Spotlight on the Researchers: Lund's Environmental Science Trailblazers

Didac Pascual, a postdoctoral fellow in Lund's Department of Earth and Environmental Sciences, led the fieldwork, emphasizing soil's overlooked role. Anders Ahlström, an associate professor there, initiated the project during his Stanford postdoc under Rob Jackson, bridging European and US expertise. Jackson, a Stanford Doerr School professor, calls the soil losses 'persistent and shocking.' Their collaboration exemplifies international academic synergy in climate research.

Lund University's Centre for Environmental and Climate Science provided key infrastructure, underscoring Sweden's higher education commitment to sustainability. Ahlström's prior work on Earth's carbon cycle informs this study, positioning Lund as a hub for boreal ecology.

Policy Ripples: Challenging Sweden's Forestry Framework

The findings critique Sweden's proposed old-growth definition—based solely on tree age (180 years north, 160 south)—as inadequate, potentially allowing logging of ecologically vital stands and undermining EU Nature Restoration Law. With unprotected old-growth vanishing at 1.4% annually (six times Amazon rates), calls grow for science-based protections. Protecting remnants and restoring logged sites could amplify Sweden's carbon sink, aligning with EU's 55% emissions cut by 2030. For details, see the full study in Science.

• Adopt holistic definitions incorporating structure, dead wood, soil.
• Halt clear-cutting in primaries; prioritize continuous cover forestry.
• Enhance carbon accounting in national reports.

Beyond Carbon: Biodiversity and Resilience Bonuses

Old-growth forests host disproportionate biodiversity—lichens, fungi, insects—resilient to disturbances like storms or pests. Managed monocultures, reliant on fertilizers and pesticides, falter under climate stress. Primaries' deep roots and diverse strata buffer droughts, preserving ecosystem services like water regulation.

Global Boreal Context: Lessons for Canada, Russia, Alaska

Sweden's boreal biome mirrors vast tracts in Canada (30% global boreal), Russia, and Alaska. Similar management may underestimate losses elsewhere. Studies suggest primaries' soil carbon stability stems from mycorrhizal fungi, warranting microbial research. Lund's model could guide inventories worldwide. Explore Lund's insights via their press release.

Future Horizons: Restoring Sweden's Carbon Legacy

Allowing secondary forests to mature could recover soil carbon over centuries, aided by reduced tillage. Emerging tech like microbial inoculants may accelerate gains. EU funding via Horizon Europe supports such trials, opening research posts.

Photo by Andrin Schranz on Unsplash

Careers in Forest Carbon Research: Europe's Growing Field

This study spotlights demand for ecologists, soil scientists, modelers in Europe. Lund and peers seek postdocs, PhDs in boreal dynamics. Skills in remote sensing, C analysis, policy analysis are prized. Sweden's universities offer competitive salaries, work-life balance.