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Title: Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change

Abstract

Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in firemore » regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.« less

Authors:
 [1];  [2];  [3];  [4];  [4];  [5];  [6];  [7]
  1. ORNL
  2. Cold and Arid Regions Environmental and Engineering Research Institute, CAS
  3. University of Alaska
  4. University of Alaska, Fairbanks
  5. USGS, Menlo Park, CA
  6. University of Maryland, College Park
  7. Canadian Forest Service
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1057945
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Ecological Applications
Additional Journal Information:
Journal Volume: 22; Journal Issue: 8; Journal ID: ISSN 1051--0761
Country of Publication:
United States
Language:
English
Subject:
assessment; basin-scale analysis; boreal forests; climate warming; C stock dynamics; dynamic organic soil; fire regime change; terrestrial ecological modeling

Citation Formats

Yuan, Fengming, Yi, Shuhua, McGuire, A. David, Johnson, Kristopher D, Liang, Jingjing, Harden, Jennifer, Kasischke, Eric S., and Kurz, Werner. Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change. United States: N. p., 2012. Web. doi:10.1890/11-1957.1.
Yuan, Fengming, Yi, Shuhua, McGuire, A. David, Johnson, Kristopher D, Liang, Jingjing, Harden, Jennifer, Kasischke, Eric S., & Kurz, Werner. Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change. United States. https://doi.org/10.1890/11-1957.1
Yuan, Fengming, Yi, Shuhua, McGuire, A. David, Johnson, Kristopher D, Liang, Jingjing, Harden, Jennifer, Kasischke, Eric S., and Kurz, Werner. 2012. "Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change". United States. https://doi.org/10.1890/11-1957.1.
@article{osti_1057945,
title = {Assessment of boreal forest historical C dynamics in Yukon River Basin: relative roles of warming and fire regime change},
author = {Yuan, Fengming and Yi, Shuhua and McGuire, A. David and Johnson, Kristopher D and Liang, Jingjing and Harden, Jennifer and Kasischke, Eric S. and Kurz, Werner},
abstractNote = {Carbon (C) dynamics of boreal forest ecosystems have substantial implications for efforts to mitigate the rise of atmospheric CO2 and may be substantially influenced by warming and changing wildfire regimes. In this study we applied a large-scale ecosystem model that included dynamics of organic soil horizons and soil organic matter characteristics of multiple pools to assess forest C stock changes of the Yukon River Basin (YRB) in Alaska, USA, and Canada from 1960 through 2006, a period characterized by substantial climate warming and increases in wildfire. The model was calibrated for major forests with data from long-term research sites and evaluated using a forest inventory database. The regional assessment indicates that forest vegetation C storage increased by 46 Tg C, but that total soil C storage did not change appreciably during this period. However, further analysis suggests that C has been continuously lost from the mineral soil horizon since warming began in the 1970s, but has increased in the amorphous organic soil horizon. Based on a factorial experiment, soil C stocks would have increased by 158 Tg C if the YRB had not undergone warming and changes in fire regime. The analysis also identified that warming and changes in fire regime were approximately equivalent in their effects on soil C storage, and interactions between these two suggests that the loss of organic horizon thickness associated with increases in wildfire made deeper soil C stocks more vulnerable to loss via decomposition. Subbasin analyses indicate that C stock changes were primarily sensitive to the fraction of burned forest area within each subbasin and that boreal forest ecosystems in the YRB are currently transitioning from being sinks to sources at ;0.7% annual area burned. We conclude that it is important for international mitigation efforts focused on controlling atmospheric CO2 to consider how climate warming and changes in fire regime may concurrently affect the CO2 sink strength of boreal forests. It is also important for large-scale biogeochemical and earth system models to include organic soil dynamics in applications to assess regional C dynamics of boreal forests responding to warming and changes in fire regime.},
doi = {10.1890/11-1957.1},
url = {https://www.osti.gov/biblio/1057945}, journal = {Ecological Applications},
issn = {1051--0761},
number = 8,
volume = 22,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}