Factors shaping alternate successional trajectories in burned black spruce forests of Alaska

• DOI: 10.1002/ecs2.3129
• Publication Date: 2020-05-05T15:10:22Z
• Authors: J. F. Johnstone; G. Celis; F. S. Chapin; T. N. Hollingsworth; M. Jean; M. C. Mack
• Keywords: Dominance (genetics); Fire regime; Black spruce; Fire ecology; Stand development

Abstract Disturbances can interrupt feedbacks that maintain stable plant community structure and create windows of opportunity for vegetation to shift alternative states. Boreal forests are dominated by tree species overlap considerably in environmental niche, but there few tests what conditions initiate sustain different forest Here, we examine patterns post‐fire growth density seedlings early succession use structural equation models estimate relative effects pre‐fire conditions, fire characteristics, biotic interactions. We surveyed seedling recruits 13 yr across a broad range ( n = 89) Alaskan black spruce stands burned 2004. Densities established at were strongly determined initial recruitment occurred within 2 after fire. High proportional combustion the soil organic layer (fire severity) led increased densities deciduous not had positive influence on aboveground biomass all species. Biotic interactions such as mammalian herbivory or woody competition, potential mechanisms relay floristic succession, no detectable biomass. Repeated surveys instead suggested persistent shifts successional trajectories communities from dominance sites where high severity created growth. Unless future alter composition, transformations observed response likely persist over short cycle increasingly characterizes regime Interior Alaska.