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

Background Fire-dependent vegetation communities in the northeastern USA have undergone significant transitions since social and ecological disruptions associated with Euro-American colonization of North America. There is much interest, though little information available, about historical fire regimes of fire-adapted vegetation communities in the northeastern USA in pre-Columbian times (i.e., pre-1492 CE). We intensively investigated a red pine (Pinus resinosa Ait.)-oak (Quercus spp.) forested landscape in north-central Pennsylvania, USA, for exceptionally old red pine remnants (stumps, snags) where previous research had suggested the potential to develop fire-scar and tree-ring chronologies which extend to time periods prior to 1492. Results Tree-ring and fire-scar chronologies recovered from red pine trees extend back to 1370 and 1402, respectively. Red pine trees were broadly distributed across this landscape (34.4 km(2) area) prior to 1492, and frequent fire (i.e., mean fire return intervals of 4.1 years at landscape scale, 9.7-11.7 years at smaller spatial scales (0.5-7.1 km(2))) was observed in the time period prior to sustained contact between Indigenous peoples and Euro-American colonizers circa 1609. Conclusions This study resulted in the longest fire-scar record in eastern North America and offers unique foundational ecological information regarding pre-Columbian fire regimes of northeastern USA fire-adapted forest communities. Fire scars provide physical evidence that fire was an important ecological component of this landscape before and after 1492 and that the current period of reduced fire activity is unprecedented in the 500 years prior to fire exclusion practices that were widely adopted circa 1915. Beyond fire scars, the spatial and temporal extent of the red pine tree-ring record provides evidence that red pine, a fire-dependent species, was historically a more important component of this landscape than it is today. The conservation of red pine vegetation communities will require incorporating recurring fire into management plans, for the successful regeneration and perpetuation of red pine, and to sustain associated flora and fauna of conservation concern.

Automated summary

This study reveals the historical fire regimes of fire-dependent vegetation communities in the northeastern USA before and after 1492. The fire-scar records provide evidence that fire was a significant ecological component in this landscape, and the red pine tree was historically more important than it is today. This information is crucial for the conservation and management of red pine vegetation communities.