Understory Plant Community Response to a Range of Restoration Scenarios in Northeast US Pitch Pine (Pinus rigida) Barrens

Aims Fire‐dependent pine and oak‐pine ecosystems of the eastern United States have been significantly impacted by their disconnection from historic disturbance regimes, particularly fire, along with changes in land use and policies of fire suppression. Climate change presents additional challenges to these communities, especially through the introduction and expansion of novel stressors. Understory plants in these communities provide important wildlife habitat, along with social and cultural value. Restoration management in northeast pitch pine ( Pinus rigida ) barrens has mainly utilized prescribed fire and mechanical treatments, including mowing and thinning. This study compared the effect of these regionally common management activities on the composition, diversity, and abundance of understory plant species. Location Pitch pine barrens in Maine, Massachusetts, New Hampshire, and New York, United States. Methods We employed systematic grid sampling, using plots to measure species diversity and estimate abundance, along with other relevant environmental conditions, in the summers of 2022 and 2023. We sampled at 47 sites across three ecoregions. We used nonmetric multi‐dimensional scaling to examine gradients in understory plant community composition across treatment types within ecoregions. Results Distinct understory community assemblages and structures were associated with different restoration strategies. This included a higher abundance of species that can endure fire and resprout from buried plant parts in prescribed fire units, whereas fire‐sensitive species and those slow to recolonize after fire events were most abundant in untreated control units. Within prescribed fire treatments, the abundance of some fire‐adapted species reflected relationships with fire severity, including Vaccinium angustifolium being associated with mowing followed by fire and Gaylusaccia baccata with areas experiencing fall burns. Restoration treatments also generated unique understory structural conditions related to treatment severity and frequency, including greater shrub densities important for several threatened wildlife species. Conclusions Impacts to understory plant community composition and structure demonstrate the importance of reinstating disturbance events, particularly fire, within pitch pine barrens to restore desired conditions and support cultural and ecological objectives.