Life cycle impacts of forest management and wood utilization on carbon mitigation: knowns and unknowns

Background

Forests currently remove 2-3 GtC yr⁻¹ from the atmosphere, while global wood harvest exceeds 3-4 billion m³ yr⁻¹, creating complex interactions between forest carbon stocks, harvested wood products, and the substitution of wood for more emission-intensive materials. Lifecycle assessment (LCA) is widely used to evaluate these interactions, but differing system boundaries, baselines, and treatment of carbon pools can lead to very different conclusions about mitigation benefits. Clarifying where evidence is robust and where major uncertainties remain is essential for designing coherent forest-climate policy.

Goals and Methods

This review synthesizes life cycle assessment studies that evaluate how forest management strategies, including rotation length, thinning regimes, and harvesting intensity, together with wood product cascading, influence net greenhouse gas balances over multi-decade timeframes. The authors compare pathways in which higher harvest levels support bioenergy or material substitution with pathways that prioritize conservation and extended rotations, assessing outcomes across 20 to 100 year horizons. The review compiles commonly reported substitution factors, typically ranging from about 0.5 to 1.5 tCO2 avoided per tCO2 stored in wood products, and critically examines how variation in these factors, along with assumptions about product longevity, shapes overall mitigation conclusions.

Conclusions and Takeaways

This review finds that strategies combining maintained or increasing forest carbon stocks with high-quality wood substitution can generate net mitigation. Still, intensive harvesting or short rotations can create carbon “debts” lasting several decades. In some scenarios, forest carbon losses of tens of Mg C ha⁻¹ over 20-40 years can offset or exceed substitution benefits, especially when substitution factors are low, or products are short-lived. The authors call for more transparent LCA practice, better empirical estimates of substitution factors by product class, and integrated assessment of biodiversity and social outcomes, so that practitioners can weigh trade-offs across hundreds of thousands of hectares of managed forests.