Fire history and vegetation data reveal ecological benefits of recent mixed-severity fires in the Cumberland Mountains, West Virginia, USA

Abstract

Abstract Background Without periodic fire, fire-adapted plant communities across the Central Hardwood Forest Region (CHF) in the USA have undergone significant changes in forest structure and species composition, most notably a decrease in oak regeneration and herbaceous diversity and an increase in shade-tolerant, fire-sensitive tree species. In this study, we conducted a comparative analysis of two mixed pine-oak (Pinus-Quercus) forests with different land management histories in the Cumberland Mountains of southern West Virginia where fire ecology and fire effects are understudied. We reconstructed the fire history of both sites from fire-scarred shortleaf pine (Pinus echinata Mill.) and pitch pine (Pinus rigida Mill.) trees to describe variation in the fire regimes over time. We also made plant community measurements that spatially coincided with fire-scarred pines to assess present-day plant community structure in relation to recent fire history. Results Before 1970, fires at Hite Fork and Wall Fork occurred frequently and almost exclusively in the dormant season, every 7–8 years on average. The fire regimes diverged in the Post-Industrial era (1970–2020), during which there was a single fire at Wall Fork, while six major fires, scarring more than 40% of sampled trees, occurred between 1985 and 2017 at Hite Fork. Four of these dormant-season fires correspond to late fall incendiary fires in the observational record. These differences in recent fire history had large effects on plant community structure. Recent mixed-severity fires at Hite Fork likely caused mortality of pole-sized trees and opened the canopy, creating conditions favorable for pine recruitment and resulted in significantly higher species richness in the herbaceous layer compared to Wall Fork, which exhibited the effects of mesophication. Conclusions Our results suggest that frequent mixed-severity fire in pine-oak forests of the Cumberland Mountains can meet management objectives by reducing mesophytic tree abundance, increasing herbaceous diversity and pine recruitment, and generally promoting forest heterogeneity.