Human augmentation of historical red pine fire regimes in the Boundary Waters Canoe Area Wilderness

Abstract

The Border Lakes Region of Minnesota and Ontario has long been viewed as a firedependent ecosystem. High-severity fire in the region's near-boreal forests has been a focus of ecological research and public fascination. However, the surface fire history within this transnational wilderness landscape has received more limited attention. We used an interdisciplinary, dendroecological approach to characterize the surface fire history of the region, assess potential drivers of historical surface fires, and document the ecological legacies of frequent fires within the red pine forests of the Boundary Waters Canoe Area Wilderness (BWCAW) in northern Minnesota. We used tree-ring and fire atlas data to reconstruct multi-century surface fire records for 101 sites and document age structure and composition at 32 sites across the BWCAW. Stratification of these sites relative to their proximity to a primary travel and trade corridor used first by Indigenous groups and later by Euro-American fur traders through the late 1800s provided strong evidence of human augmentation of fires. The patterns of fire activity, fire-climate relationships, and forest development indicate that traditional landuse by Anishinaabeg (Ojibwe) increased rates of local surface fire and played an important role in shaping the landscape. The decline of traditional subsistence practices by the Border Lakes Anishinaabeg coincided with a sharp decline in surface fires and a period of abundant tree establishment. In the absence of repeat surface fires, many red pine sites have shifted in composition, increased in stem density, and grown vulnerable to forest-type conversion through future high-severity fire. These results highlight the need for active fire reintroduction to red pine forests of the Great Lakes Region and underscore the importance of collaboration and guidance from Indigenous Knowledge Keepers in this process. A blended knowledge approach to fire restoration that directly engages with Indigenous perspectives and cultural practices can perpetuate the distinctive character of the largest remaining tracts of long-lived pine forest in the Great Lakes Region. Carefully developed fire restoration practices would enhance the visitor use experience within one of the most frequently visited wilderness areas in the United States while re-engaging directly with Indigenous knowledge and traditional cultural practices.

The North American tree‐ring fire‐scar network

“…1900 in the western United States and the Great Lakes region. The latter is likely related to the restriction of Indigenous populations coincident with Euro‐American settlement (Kipfmueller et al, 2021). Interestingly, in some regions where the most recent fire scar dates are close to the present, European settlement was the earliest (in the 15th–17th centuries); this encompasses areas with intact traditional fire use (e.g., in Mexico; Martínez‐Torres et al, 2016) or where prescribed and resource benefit fires are a priority for local stakeholders (e.g., the southeastern and south‐central United States; Rother et al, 2020).…”

“…Increased coverage in Canada and Alaska is ongoing and should be prioritized to better understand these important regions where climate change is rapidly increasing fire activity (Whitman et al, 2019). Targeting areas with the potential for longer records (i.e., prior to 1700 CE) in eastern North America would be beneficial for studying the changes in ecosystems and fire regimes related to European colonization and displacement and decline of Native American populations and cultural practices (Guyette et al, 2002; Kipfmueller et al, 2021; Stambaugh et al, 2018). Characterizing the environmental conditions of existing older sites in undersampled regions (e.g., topography or geologic features such as exposed rock that can reduce rates of wood decay or moderate fire behavior) could be fruitful to systematically target potential new areas for older fire records.…”

“…Guyette et al (2012) identified major climate drivers of historical fire frequency for the United States using the physical chemistry fire frequency model and a network of 170 fire history sites. Fire‐scar networks have also revealed important contexts for changing vegetation and landscape dynamics (Dewar et al, 2021; Lafon et al, 2017; O'Connor et al, 2017) and human influences on fire regimes (Collins & Stephens, 2007; Guyette et al, 2002; Kipfmueller et al, 2021; Kitchen, 2015; Swetnam et al, 2016). Regional fire‐scar networks were key to identifying the anomaly of 20th century fire exclusion in large parts of the United States (Guyette et al, 2002; Swetnam & Baisan, 1996), thereby shaping national fire policies.…”

Pre-Columbian red pine (Pinus resinosa Ait.) fire regimes of north-central Pennsylvania, USA

“…Existing research indicates that considerable potential exists to develop temporally long fire-scar chronologies using red pine (P. resinosa Ait.) remnant wood (e.g., Brose et al 2013Brose et al , 2015Kipfmueller et al 2021;Mann et al 1994;Marschall et al 2019). Red pine is an ideal tree species for fire-scar chronology development due to its abilities to survive and record low-to-moderate severity fires (Hauser 2008), and to persist as remnant wood for centuries post-mortem.…”

A review of the scientific contributions enabled by wilderness fire management

“…The joint effects of the Leopold report (Leopold et al, 1963), which stimulated the National Park Service to recognize re as an ecological process (Hunter et al, 2014), and the Wilderness Act, which prompted Forest Service managers in the US Northern Rocky Mountains to manage some natural ignitions (Smith, 2014;Berkey et al, 2021b), began to restore re as an ecological process and management tool starting in the late 1960s and early 1970s. These policy and management changes followed many decades of diminished re activity due to the 1935 10 AM Policy-a national policy to suppress all wild re ignitions-and earlier depopulation and displacement of Native Americans and their use of re (Kimmerer and Lake, 2001;Ostlund et al, 2005;Kipfmueller et al, 2021;Larson et al, 2021). This shift towards a greater acceptance of re created opportunities to study re as an ecological and landscape process and interactions of wild re with people and socioeconomic systems.…”