Evaluating the lifecycle sustainability of forestry value chains

Abstract

To meet the Paris Agreement's target of net-zero greenhouse gas (GHG) emissions by 2050, urgent action is required, with forestry value chains playing a key role. Forests sequester atmospheric CO2 as trees grow, and harvested wood products (HWP) store carbon while replacing GHG-intensive alternatives like concrete, steel, and fossil fuels. Wood use can help decarbonise high-emitting sectors such as construction, with demand expected to rise. However, increasing wood demand may strain existing forests, raising concerns about whether forestry value chains can meet this demand while delivering climate-change mitigation (i.e. net negative GHG emissions). The best forest type for effective mitigation, ranging from natural to intensively managed commercial forests, is also debated.
Most studies focus either on forest systems or wood processing and use, missing a comprehensive view of the entire forestry value chain. Lifecycle assessment (LCA) (systems an internationally recognised approach to evaluating environmental impact) is needed to evaluate the environmental impact of these. Consequential LCA (cLCA) calculates net changes in environmental impacts in response to an action, including changes outside the focal product system, due to market forces; and can be used to evaluate the relative impact of proposed actions and support strategic prioritisation. This study uses cLCA to assess the climate-change mitigation efficacy of strategies such as afforestation, improved forest management, and circular wood use. The aim is to support a systemic shift to a circular bioeconomy. The study considers future system components like industrial decarbonisation, new technologies (e.g., bioenergy with carbon capture and storage), new circular business models, and changing wood demand. The geographical focus is a generic temperate country, including a UK case study, while accounting for global wood trade and overseas impacts of HWP imports.
To identify barriers and enabling actions for a circular bioeconomy, key expert stakeholders across the UK forestry value chain were interviewed. Their responses were evaluated against seven change functions: visioning, organizing, resourcing, learning, measuring, advocating, and prototyping. The study shows that increased wood use can help mitigate climate change, but only if coordinated with afforestation and improved forest productivity. High wood demand may undermine mitigation if forest carbon loss exceeds the benefits of wood use, making efficient wood use crucial. Commercial afforestation delivers 269% more mitigation than semi-natural afforestation over 100 years in a UK context, with the results robust across wood-use types. However, afforestation’s mitigation impact grows gradually, while increasing circular wood use can deliver near-term mitigation by reducing pressure on forests. A modelled scenario with medium density fibreboard (MDF) recycling delivered 75% more cumulative mitigation by 2050 compared to business-as-usual wood use. Circularity complements afforestation and improved management, but requires cross-industry collaboration, national policy coherence, and advocacy for a shared vision.
This thesis challenges negative views on commercial forestry’s climate-change mitigation potential and proposes effective policy and practices to enhance forestry value chains’ contributions to the Paris Agreement’s net-zero target. Study limitations include simplified assumptions on albedo effects, which may need further testing. Recommendations for future research include evaluating trade-offs between mitigation and other ecosystem services, and applying prospective cLCA to different forestry value chains, including forests with varying growth rates in different climatic zones.

Date of Award	17 Dec 2024
Original language	English
Awarding Institution	Bangor University
Sponsors	Woodknowledge Wales & Coed Cymru
Supervisor	John Healey (Supervisor) & David Styles (Supervisor)