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Title: Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment

Here, we are conducting a large-scale, long-term climate change response experiment in an ombrotrophic peat bog in Minnesota to evaluate the effects of warming and elevated CO 2 on ecosystem processes using empirical and modeling approaches. To better frame future assessments of peatland responses to climate change, we characterized and compared spatial vs. temporal variation in measured C cycle processes and their environmental drivers. We also conducted a sensitivity analysis of a peatland C model to identify how variation in ecosystem parameters contributes to model prediction uncertainty. High spatial variability in C cycle processes resulted in the inability to determine if the bog was a C source or sink, as the 95% confidence interval ranged from a source of 50 g C m –2 yr –1 to a sink of 67 g C m –2 yr –1. Model sensitivity analysis also identified that spatial variation in tree and shrub photosynthesis, allocation characteristics, and maintenance respiration all contributed to large variations in the pretreatment estimates of net C balance. Variation in ecosystem processes can be more thoroughly characterized if more measurements are collected for parameters that are highly variable over space and time, and especially if those measurements encompass environmental gradientsmore » that may be driving the spatial and temporal variation (e.g., hummock vs. hollow microtopographies, and wet vs. dry years). Together, the coupled modeling and empirical approaches indicate that variability in C cycle processes and their drivers must be taken into account when interpreting the significance of experimental warming and elevated CO 2 treatments.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [5] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Linnaeus Univ., Vaxjo (Sweden)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  5. USDA Forest Service, Grand Rapids, MN (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-716257; SAND2018-9625J
Journal ID: ISSN 0361-5995
Grant/Contract Number:
AC52-07NA27344; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Soil Science Society of America Journal
Additional Journal Information:
Journal Volume: 81; Journal Issue: 6; Journal ID: ISSN 0361-5995
Publisher:
Alliance of Crop, Soil, and Environmental Science Societies
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; spatial and temporal variability; uncertainty; bog; carbon cycle
OSTI Identifier:
1429218
Alternate Identifier(s):
OSTI ID: 1420286; OSTI ID: 1472267

Griffiths, Natalie A., Hanson, Paul J., Ricciuto, Daniel M., Iversen, Colleen M., Jensen, Anna M., Malhotra, Avni, McFarlane, Karis J., Norby, Richard J., Sargsyan, Khachik, Sebestyen, Stephen D., Shi, Xiaoying, Walker, Anthony P., Ward, Eric J., Warren, Jeffrey M., and Weston, David J.. Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment. United States: N. p., Web. doi:10.2136/sssaj2016.12.0422.
Griffiths, Natalie A., Hanson, Paul J., Ricciuto, Daniel M., Iversen, Colleen M., Jensen, Anna M., Malhotra, Avni, McFarlane, Karis J., Norby, Richard J., Sargsyan, Khachik, Sebestyen, Stephen D., Shi, Xiaoying, Walker, Anthony P., Ward, Eric J., Warren, Jeffrey M., & Weston, David J.. Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment. United States. doi:10.2136/sssaj2016.12.0422.
Griffiths, Natalie A., Hanson, Paul J., Ricciuto, Daniel M., Iversen, Colleen M., Jensen, Anna M., Malhotra, Avni, McFarlane, Karis J., Norby, Richard J., Sargsyan, Khachik, Sebestyen, Stephen D., Shi, Xiaoying, Walker, Anthony P., Ward, Eric J., Warren, Jeffrey M., and Weston, David J.. 2017. "Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment". United States. doi:10.2136/sssaj2016.12.0422. https://www.osti.gov/servlets/purl/1429218.
@article{osti_1429218,
title = {Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment},
author = {Griffiths, Natalie A. and Hanson, Paul J. and Ricciuto, Daniel M. and Iversen, Colleen M. and Jensen, Anna M. and Malhotra, Avni and McFarlane, Karis J. and Norby, Richard J. and Sargsyan, Khachik and Sebestyen, Stephen D. and Shi, Xiaoying and Walker, Anthony P. and Ward, Eric J. and Warren, Jeffrey M. and Weston, David J.},
abstractNote = {Here, we are conducting a large-scale, long-term climate change response experiment in an ombrotrophic peat bog in Minnesota to evaluate the effects of warming and elevated CO2 on ecosystem processes using empirical and modeling approaches. To better frame future assessments of peatland responses to climate change, we characterized and compared spatial vs. temporal variation in measured C cycle processes and their environmental drivers. We also conducted a sensitivity analysis of a peatland C model to identify how variation in ecosystem parameters contributes to model prediction uncertainty. High spatial variability in C cycle processes resulted in the inability to determine if the bog was a C source or sink, as the 95% confidence interval ranged from a source of 50 g C m–2 yr–1 to a sink of 67 g C m–2 yr–1. Model sensitivity analysis also identified that spatial variation in tree and shrub photosynthesis, allocation characteristics, and maintenance respiration all contributed to large variations in the pretreatment estimates of net C balance. Variation in ecosystem processes can be more thoroughly characterized if more measurements are collected for parameters that are highly variable over space and time, and especially if those measurements encompass environmental gradients that may be driving the spatial and temporal variation (e.g., hummock vs. hollow microtopographies, and wet vs. dry years). Together, the coupled modeling and empirical approaches indicate that variability in C cycle processes and their drivers must be taken into account when interpreting the significance of experimental warming and elevated CO2 treatments.},
doi = {10.2136/sssaj2016.12.0422},
journal = {Soil Science Society of America Journal},
number = 6,
volume = 81,
place = {United States},
year = {2017},
month = {11}
}