Substantial and increasing global losses of timber-producing forest due to wildfires

Timber is a crucial global resource, contributing over US$1.5 trillion to national economies in 2015. At least one-third of global forests are used for timber production, a demand projected to nearly triple by 2050. Wildfires, a natural process in many ecosystems, are increasing in frequency and severity due to climate change, posing a significant threat to timber production. High-severity, stand-replacing wildfires severely impact timber stocks, particularly given the long-term nature of timber production cycles (40–100+ years). This study addresses the lack of understanding of wildfire's influence on global timber production by combining spatial data on forestry practices with annual data on wildfire-induced forest loss to assess the extent and temporal trends of wildfire-induced losses in timber-producing forests globally.

Previous research has documented increasing forest loss due to wildfires in the 21st century, with over 110 million hectares lost between 2001 and 2019. Studies predict significant increases in fire season length and extent by 2100 due to climate change. Existing literature highlights the threat of high-severity wildfires to timber stocks in managed forests, emphasizing the need for understanding the location and rate of fire-induced losses to ensure the maintenance of timber production in a changing climate. Several studies have provided global maps of forest management practices and forest loss due to various drivers, including wildfire. This study utilizes these existing datasets to investigate the specific impact of wildfires on timber production.

Two datasets mapping global logging activity were used: Lesiv et al.'s global map of forest management (100 m resolution) and Curtis et al.'s global map of forestry as the dominant driver of forest cover loss (10 km resolution). These were overlaid with Tyukavina et al.'s global data on stand-replacing wildfires (30 m resolution). The Lesiv et al. data included naturally regenerating managed forests, planted forests (>15 years rotation), and plantation forests (≤15 years rotation). The Curtis et al. data categorized forest loss by driver, including forestry. Both logging layers were overlaid with the wildfire data to identify areas where timber-producing forests were affected. A third dataset from Schulze et al., based on FAO data, was also considered but not included in the main analysis due to inconsistencies and limitations in data reporting and classification. A forest cover mask from Hansen et al. was applied to the Curtis et al. layer to ensure only areas with >10% tree cover were included. Analysis was conducted at global, regional, and national scales, utilizing R software packages for spatial data analysis and trend analysis (Mann–Kendall test and Sen's slope). The study also estimated the economic cost of timber losses based on FAO data and global timber export prices, considering potential losses from salvage logging.

Between 2001 and 2021, 18.5–24.7 million hectares of timber-producing forest were lost to wildfires globally—an area roughly the size of Great Britain. This represents 1.0–1.7% of global forestry land. Losses were particularly high in northwestern USA and Canada, northeastern Russia, southeastern Australia, and Brazil. Russia, the USA, and Canada experienced the largest absolute losses. Portugal and Australia showed the highest percentage losses of forestry land. Annual burned area increased significantly from 2001 to 2021 globally (Mann–Kendall test, *P* = 0.0008, Sen's slope annual trend size = +68,400 ha yr−1 using Lesiv et al. data; *P* = 0.02, annual trend size = +37,800 ha yr−1 using Curtis et al. data), with a sharper increase after 2015. Regional increases in burned area were observed in all regions except Eurasia. Three of the five largest timber-producing nations (USA, Canada, and Brazil) showed increasing trends in burned area. The estimated economic loss of timber from wildfires (2001–2021) was ~US$45–77 billion. Using Lesiv et al. data, ~8.1 Mha of burned timber-producing forest were identified in the tropics, particularly in Latin America.

The significant and increasing loss of timber-producing forests to wildfires highlights a serious threat to global timber supply. The increasing trend aligns with predictions of more frequent and severe wildfires under climate change. The findings underscore the need for proactive strategies, including improved forest management practices, spatial planning of forestry activities, and adoption of new technologies for fire detection and suppression. The variation in results between the different logging datasets highlights the challenges and uncertainties in accurately mapping and quantifying global forestry practices. Despite limitations in data availability and accuracy, the study’s findings consistently show a substantial and growing threat to global timber production from wildfires.

Stand-replacing wildfires have caused substantial and increasing losses of timber-producing forests. The economic consequences are significant, and the trend is projected to worsen under climate change. To ensure future timber supply, the adoption of proactive management strategies, including improved spatial planning, species selection, and technological advancements in fire detection and suppression, is urgently needed. Future research should focus on refining methods for mapping forest management practices, improving fire prediction models, and developing effective post-fire management strategies.

The study's findings are subject to uncertainties related to the accuracy and resolution of the datasets used. The different logging datasets showed some variation in national-level patterns, potentially due to differences in mapping methodologies and accuracy. The economic estimates are based on assumptions regarding salvage logging and timber prices, which may introduce some uncertainty. The analysis focuses on stand-replacing wildfires and may not fully capture the impacts of low-severity fires.