title: Dispersal limitation drives successional pathways in Central Siberian forests under current and intensified fire regimes.
abstract: Fire is a primary driver of boreal forest dynamics. Intensifying fire regimes due to climate change may cause a shift in boreal forest composition toward reduced dominance of conifers and greater abundance of deciduous hardwoods, with potential biogeochemical and biophysical feedbacks to regional and global climate. This shift has already been observed in some North American boreal forests and has been attributed to changes in site conditions. However, it is unknown if the mechanisms controlling fire-induced changes in deciduous hardwood cover are similar among different boreal forests, which differ in the ecological traits of the dominant tree species. To better understand the consequences of intensifying fire regimes in boreal forests, we studied postfire regeneration in five burns in the Central Siberian dark taiga, a vast but poorly studied boreal region. We combined field measurements, dendrochronological analysis, and seed-source maps derived from high-resolution satellite images to quantify the importance of site conditions (e.g., organic layer depth) vs. seed availability in shaping postfire regeneration. We show that dispersal limitation of evergreen conifers was the main factor determining postfire regeneration composition and density. Site conditions had significant but weaker effects. We used information on postfire regeneration to develop a classification scheme for successional pathways, representing the dominance of deciduous hardwoods vs. evergreen conifers at different successional stages. We estimated the spatial distribution of different successional pathways under alternative fire regime scenarios. Under intensified fire regimes, dispersal limitation of evergreen conifers is predicted to become more severe, primarily due to reduced abundance of surviving seed sources within burned areas. Increased dispersal limitation of evergreen conifers, in turn, is predicted to increase the prevalence of successional pathways dominated by deciduous hardwoods. The likely fire-induced shift toward greater deciduous hardwood cover may affect climate-vegetation feedbacks via surface albedo, Bowen ratio, and carbon cycling.
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, 07745, Jena, Germany.|Department of Biosciences, TU Bergakademie Freiberg, Leipziger Strasse 29, 09596, Freiberg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Tautenhahn
authors.affiliation: Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Lichstein
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, 07745, Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Jung
authors.affiliation: Max Planck Institute for Biogeochemistry, Hans-Knöll-Strasse 10, 07745, Jena, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kattge
authors.affiliation: School of Forest Resources and Conservation, University of Florida, Gainesville, FL, 32611, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Bohlman
authors.affiliation: Department of Biosciences, TU Bergakademie Freiberg, Leipziger Strasse 29, 09596, Freiberg, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Heilmeier
authors.affiliation: Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, Akademgorodok 50/28, Krasnoyarsk, 660036, Russia.
authors.forename: Anatoly
authors.initials: A
authors.lastname: Prokushkin
authors.affiliation: University of Leipzig, Johannisallee 21-23, 04103, Leipzig, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Kahl
authors.affiliation: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.|University of Leipzig, Johannisallee 21-23, 04103, Leipzig, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wirth
mesh_terms: D002980:Climate; D004784:Environmental Monitoring; D005390:Fires; D063148:Plant Dispersal; D012800:Siberia; D066188:Taiga; D064028:Tracheophyta / Q000254:growth & development*; D014197:Trees / Q000254:growth & development*
keywords: boosted regression trees; boreal; dark taiga; fire regime; forest regeneration; land surface-climate feedback; postfire succession; residual seed trees; seed dispersal