JFSP_research_product_search

Project ID:

24-2-04-2

Year:

2024

Date Started:

04/01/2024

Date Completed:

Title:

Impacts of fire severity, permafrost thaw, and successsion on the boreal forest carbon balance

Project Proposal Abstract:

1. Problem Statement
Increasing wildfire disturbance is one of the most rapid pathways through which climate warming could alter the structure and function of northern ecosystems. Historically, northwestern North American boreal forest ecosystems have acted as a net carbon (C) sink, accumulating C from the atmosphere in thick, old organic soil layers over numerous fire cycles and centuries. Fires can shift the C balance of this ecosystem from a C sink to a net C source to the atmosphere via direct combustion of the soil organic layer. Disturbance of the soil organic layer can also trigger changes in C inputs by altering successional trajectories of plant dominance and C losses by exposing permafrost soils to warmer temperatures, leading to ground subsidence and destabilization of old permafrost C. The balance among these C cycling pathways will determine the fate of the boreal forest C sink. Understanding how wildfire severity, ground subsidence, and successional trajectories impact soil C loss and reaccumulation is critical for informing effective management strategies to mitigate the impact of increasing wildfires on the long-term C balance of northern ecosystems.

2. Objectives
In the proposed research, we will assess the impact of wildfire severity, ground subsidence, and successional trajectories on the loss of soil C from boreal forest ecosystems. We hypothesize that fire-induced soil C loss will be greatest: 1) with high severity fires and deep burning of the organic soil layer, 2) in areas with high post-fire subsidence where permafrost is degraded, and 3) with alternate vegetation successional trajectories that inhibit the recovery of the soil organic layer. We have a unique opportunity to test these hypotheses because we archived soils from the initial sampling of these sites 20 years ago. We will examine changes in C pools of the organic soil layer, the mineral soil active layer, and previously frozen permafrost soil. We will use 14C measurements to assess the relative contributions of soil C loss and new soil C inputs to changes in the soil C pools of the organic and mineral soil layers. We will use a constant soil ash-mass method to account for subsiding permafrost ground to determine decadal-scale loss of deep permafrost soil C following fire.

3. Benefits
Wildfires have profound effects on ecosystem structure and function, feedbacks to climate, and human society. For stakeholders in the global climate system, including policymakers, we will improve our understanding of how environmental change affects C cycling feedbacks to climate. For regional and local stakeholders, we will enhance our ability to identify where old soil C pools are likely to be lost after wildfire. We will work with the Alaska Fire Science Consortium, National Park Service, and US Fish and Wildlife Service (see letters of support) to coordinate knowledge exchange with local, state, and federal fire managers. This collaboration will improve our research approach and the impact of our conclusions. Through this partnership, we will participate in the Alaska Fall Fire Review and develop technology transfer products such as research briefs, webinar presentations, and newsletter updates.

Principal Investigator:

Xanthe J Walker

Agency/Organization:

Northern Arizona University

Branch or Dept:

Other Project Collaborators

Type	Name	Agency/Organization	Branch or Dept
Agreements Contact	Samaneh Moeini	Northern Arizona University	Office of Grant & Contract Service
Budget Contact	Samaneh Moeini	Northern Arizona University	Office of Grant & Contract Service
Co-Principal Investigator	Edward Schuur	University of Florida	Department of Biology
Co-Principal Investigator	Michelle C. Mack	Northern Arizona University