Ground flora cover, diversity, and life‐history trait representation after wind disturbance, salvage logging, and prescribed fire in a Pinus palustris woodland

Abstract

Question: Salvage logging and prescribed fire are commonly applied in forests worldwide, yet little is known about the combined impacts of these management actions on early-successional ecosystems. We questioned how operational-scale prescribed fire would affect ground flora cover, species diversity, and life-history trait expression in Pinus palustris woodlands differentially impacted by an Enhanced Fujita scale 3 (EF3) tornado and salvage logging. Location: Fall Line Hills, Alabama, USA (32°55ʹ30ʺ N, 87°24ʹ00ʺ W). Methods: The composition and foliar cover of woody and herbaceous plants ≤1 m height were monitored before and after prescribed fire in 600 1-m 2 quadrats distributed throughout mature, wind-disturbed, and salvage-logged Pinus palustris woodlands. Plant taxa were categorized by growth habit and life form to aid interpretation of multivariate analyses used to illustrate differences in ground flora assemblages between disturbance categories. Results: Prescribed fire reduced ground flora cover, but not diversity, which remained greatest in wind-disturbed sites that were not salvage-logged. Though ground flora assemblages remained disparate between disturbance categories, prescribed fire imposed some consistent selective pressures on plants with common life-history strategies. Post-fire understorey tree cover reductions coincided with increased shrub cover throughout the treatment area. Nonetheless, differences in graminoid cover were exaggerated after prescribed fire, and representation of the geophyte life form was relatively constant across space and time. Conclusions: Prescribed fire did not counteract salvage-mediated reductions in ground flora diversity. Retention of downed deadwood maximized early-successional plant diversity in wind-disturbed sites. Trait-based ground flora analyses enabled a more detailed understanding of disturbance effects than aggregate metrics of foliar cover and diversity. In ecosystems with high floristic diversity, grouping plants by common life-history traits can provide a simple and effective means to monitor impacts of management actions on ecosystem recovery.