Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model

Yihui Wang; Fengming Yuan; Fenghui Yuan; Baohua Gu; Melanie S. Hahn; Margaret S. Torn; Daniel M. Ricciuto; Jitendra Kumar; Liyuan He; Donatella Zona; David A. Lipson; Robert Wagner; Walter C. Oechel; Stan D. Wullschleger; Peter E. Thornton; Xiaofeng Xu

doi:10.1029/2019MS001771

Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model

Yihui Wang, Fengming Yuan, Fenghui Yuan, Baohua Gu, Melanie S. Hahn, Margaret S. Torn, Daniel M. Ricciuto, Jitendra Kumar, Liyuan He, Donatella Zona, David A. Lipson, Robert Wagner, Walter C. Oechel, Stan D. Wullschleger, Peter E. Thornton, Xiaofeng Xu

Earth Systems Modeling

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO₂ and CH₄ fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO₂ and CH₄ fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO₂ and CH₄ fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH₄ emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO₂ + H₂) is the most important factor determining CH₄ emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH₄ emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH₄ fluxes. The model underestimated the EC-measured CH₄ flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH₄ flux. The strong microtopographic impacts on CO₂ and CH₄ fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape.

Original language	English
Pages (from-to)	4288-4304
Number of pages	17
Journal	Journal of Advances in Modeling Earth Systems
Volume	11
Issue number	12
DOIs	https://doi.org/10.1029/2019MS001771
State	Published - Dec 1 2019

Funding

We are grateful to Randy A. Dahlgren from University of California, Davis for his constructive suggestions for results interpretation. The authors are grateful for financial and facility support from San Diego State University. Financial assistance was partially provided by the SPRUCE and NGEE Arctic projects, which are supported by the Office of Biological and Environmental Research in the Department of Energy Office of Science. This project is partially supported by the U.S. National Science Foundation (1702797).

Keywords

Arctic tundra
CH flux
microtopographic
net carbon exchange
sensitivity analysis

Access to Document

10.1029/2019MS001771

Cite this

Wang, Y., Yuan, F., Yuan, F., Gu, B., Hahn, M. S., Torn, M. S., Ricciuto, D. M., Kumar, J., He, L., Zona, D., Lipson, D. A., Wagner, R., Oechel, W. C., Wullschleger, S. D., Thornton, P. E., & Xu, X. (2019). Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model. Journal of Advances in Modeling Earth Systems, 11(12), 4288-4304. https://doi.org/10.1029/2019MS001771

@article{aaec226c4cb04efab481a9e8002f8383,

title = "Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model",

abstract = "Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO2 and CH4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO2 and CH4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO2 and CH4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH4 emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO2 + H2) is the most important factor determining CH4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH4 fluxes. The model underestimated the EC-measured CH4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH4 flux. The strong microtopographic impacts on CO2 and CH4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape.",

keywords = "Arctic tundra, CH flux, microtopographic, net carbon exchange, sensitivity analysis",

author = "Yihui Wang and Fengming Yuan and Fenghui Yuan and Baohua Gu and Hahn, {Melanie S.} and Torn, {Margaret S.} and Ricciuto, {Daniel M.} and Jitendra Kumar and Liyuan He and Donatella Zona and Lipson, {David A.} and Robert Wagner and Oechel, {Walter C.} and Wullschleger, {Stan D.} and Thornton, {Peter E.} and Xiaofeng Xu",

note = "Publisher Copyright: {\textcopyright}2019. The Authors.",

year = "2019",

month = dec,

day = "1",

doi = "10.1029/2019MS001771",

language = "English",

volume = "11",

pages = "4288--4304",

journal = "Journal of Advances in Modeling Earth Systems",

issn = "1942-2466",

publisher = "Wiley Open Access",

number = "12",

}

Wang, Y, Yuan, F, Yuan, F, Gu, B, Hahn, MS, Torn, MS, Ricciuto, DM , Kumar, J , He, L, Zona, D, Lipson, DA, Wagner, R, Oechel, WC, Wullschleger, SD, Thornton, PE & Xu, X 2019, 'Mechanistic Modeling of Microtopographic Impacts on CO₂ and CH₄ Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model', Journal of Advances in Modeling Earth Systems, vol. 11, no. 12, pp. 4288-4304. https://doi.org/10.1029/2019MS001771

TY - JOUR

T1 - Mechanistic Modeling of Microtopographic Impacts on CO2 and CH4 Fluxes in an Alaskan Tundra Ecosystem Using the CLM-Microbe Model

AU - Wang, Yihui

AU - Yuan, Fengming

AU - Yuan, Fenghui

AU - Gu, Baohua

AU - Hahn, Melanie S.

AU - Torn, Margaret S.

AU - Ricciuto, Daniel M.

AU - Kumar, Jitendra

AU - He, Liyuan

AU - Zona, Donatella

AU - Lipson, David A.

AU - Wagner, Robert

AU - Oechel, Walter C.

AU - Wullschleger, Stan D.

AU - Thornton, Peter E.

AU - Xu, Xiaofeng

PY - 2019/12/1

Y1 - 2019/12/1

N2 - Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO2 and CH4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO2 and CH4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO2 and CH4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH4 emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO2 + H2) is the most important factor determining CH4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH4 fluxes. The model underestimated the EC-measured CH4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH4 flux. The strong microtopographic impacts on CO2 and CH4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape.

AB - Spatial heterogeneities in soil hydrology have been confirmed as a key control on CO2 and CH4 fluxes in the Arctic tundra ecosystem. In this study, we applied a mechanistic ecosystem model, CLM-Microbe, to examine the microtopographic impacts on CO2 and CH4 fluxes across seven landscape types in Utqiaġvik, Alaska: trough, low-centered polygon (LCP) center, LCP transition, LCP rim, high-centered polygon (HCP) center, HCP transition, and HCP rim. We first validated the CLM-Microbe model against static-chamber measured CO2 and CH4 fluxes in 2013 for three landscape types: trough, LCP center, and LCP rim. Model application showed that low-elevation and thus wetter landscape types (i.e., trough, transitions, and LCP center) had larger CH4 emissions rates with greater seasonal variations than high-elevation and drier landscape types (rims and HCP center). Sensitivity analysis indicated that substrate availability for methanogenesis (acetate, CO2 + H2) is the most important factor determining CH4 emission, and vegetation physiological properties largely affect the net ecosystem carbon exchange and ecosystem respiration in Arctic tundra ecosystems. Modeled CH4 emissions for different microtopographic features were upscaled to the eddy covariance (EC) domain with an area-weighted approach before validation against EC-measured CH4 fluxes. The model underestimated the EC-measured CH4 flux by 20% and 25% at daily and hourly time steps, suggesting the importance of the time step in reporting CH4 flux. The strong microtopographic impacts on CO2 and CH4 fluxes call for a model-data integration framework for better understanding and predicting carbon flux in the highly heterogeneous Arctic landscape.

KW - Arctic tundra

KW - CH flux

KW - microtopographic

KW - net carbon exchange

KW - sensitivity analysis

UR - http://www.scopus.com/inward/record.url?scp=85076412325&partnerID=8YFLogxK

U2 - 10.1029/2019MS001771

DO - 10.1029/2019MS001771

M3 - Article

AN - SCOPUS:85076412325

SN - 1942-2466

VL - 11

SP - 4288

EP - 4304

JO - Journal of Advances in Modeling Earth Systems

JF - Journal of Advances in Modeling Earth Systems

IS - 12

ER -