Ecosystems

, Volume 19, Issue 1, pp 98–114

A Canopy Shift in Interior Alaskan Boreal Forests: Consequences for Above- and Belowground Carbon and Nitrogen Pools during Post-fire Succession

Article

DOI: 10.1007/s10021-015-9920-7

Cite this article as:
Alexander, H.D. & Mack, M.C. Ecosystems (2016) 19: 98. doi:10.1007/s10021-015-9920-7

Abstract

Global change models predict that high-latitude boreal forests will become increasingly susceptible to fire activity as climate warms, possibly causing a positive feedback to warming through fire-driven emissions of CO2 into the atmosphere. However, fire-climate feedbacks depend on forest regrowth and carbon (C) accumulation over the post-fire successional interval, which is influenced by nitrogen (N) availability. To improve our understanding of post-fire C and N accumulation patterns in boreal forests, we evaluated above- and belowground C and N pools within 70 stands throughout interior Alaska, a region predicted to undergo a shift in canopy dominance as fire severity increases. Stands represented gradients in age and successional trajectory, from black spruce (Picea mariana) self-replacement to species replacement by deciduous species of trembling aspen (Populus tremuloides) and Alaska paper birch (Betula neoalaskana). Stands undergoing deciduous trajectories stored proportionally more of their C and N in aboveground stemwood and had 5–7 times faster rates of aboveground net primary productivity of trees compared to stands undergoing a black spruce trajectory, which stored more of their C and N in the soil organic layer (SOL), a thick layer of mostly undecomposed mosses. Thus, as successional trajectories shift, total C and N pool sizes will remain relatively unchanged, but there will be a trade-off in pool location and a potential increase in C and N longevity due to decreased flammability and decomposition rates of deciduous stemwood. Despite often warmer, drier conditions in deciduous compared to black spruce stands, deciduous stemwood has a C:N around 10 times higher than the black spruce SOL and often remains standing for many years with reduced exposure to fungal decomposers. Thus, a fire-driven shift in successional trajectories could cause a negative feedback to climate warming because of increased pool longevity in deciduous trajectories.

Keywords

Climate warming Fire Carbon Nitrogen Succession Black spruce Trembling aspen Alaska paper birch Deciduous 

Supplementary material

10021_2015_9920_MOESM1_ESM.docx (19 kb)
Supplementary material 1 (DOCX 18 kb)

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Department of ForestryForest and Wildlife Research CenterMississippi State UniversityUSA
  2. 2.Center for Ecosystem Science and SocietyNorthern Arizona UniversityFlagstaffUSA

Personalised recommendations