Abstract

Abstract Upland forest soils are typically major atmospheric carbon dioxide (CO ₂ ) sources and methane (CH ₄ ) sinks, but the contributions of root and microbial processes, as well as their separate temporal responses to environmental change, remain poorly understood. This 2‐year study was conducted in a temperate, deciduous forest located on the Chesapeake Bay in Maryland, USA. We used temporal CO ₂ and CH ₄ flux measurements, exclusion‐source partitioning, and an ecosystem‐scale flooding experiment to understand how carbon (C) fluxes, and their root and microbial sources, respond to seasonal and episodic environmental change. We show that the root‐and‐rhizosphere component of soil CO ₂ and CH ₄ flux is significant and that its dependence on soil temperature and volumetric water content (VWC) influences soil C dynamics at seasonal timescales. Experimental flooding shows that CO ₂ and CH ₄ flux responses to episodic moisture change were driven by suppression of soil heterotrophs, while root respiration did not respond to transient hydrologic disturbance. Methane uptake responded strongly to episodic inundation, reinforcing the important role of soil moisture in the short‐term control of the forest soil CH ₄ sink. However, despite the clear seasonality of CH ₄ uptake, as well as itsmore » strong response to short‐term experimental inundation, temperature and VWC were weak predictors of CH ₄ uptake at a seasonal timescale. We suggest that CH ₄ consumption in the long‐term may be determined by vegetation, nutrients, microbial communities, or other factors correlated with seasonal changes. Our results indicate that root and microbial sources of both CO ₂ and CH ₄ flux respond differently in timing and magnitude to seasonal and episodic environmental change.« less

Authors:

Hopple, Anya M.  ^[1];

• Search DOE PAGES for author "Hopple, Anya M."
• Search DOE PAGES for ORCID "0000-0002-5957-8603"

Pennington, Stephanie C.  ^[2];

• Search DOE PAGES for author "Pennington, Stephanie C."
• Search DOE PAGES for ORCID "0000-0003-2685-1092"

Megonigal, James Patrick  ^[3];

• Search DOE PAGES for author "Megonigal, James Patrick"
• Search DOE PAGES for ORCID "0000-0002-2018-7883"

Bailey, Vanessa  ^[4];

• Search DOE PAGES for author "Bailey, Vanessa"
• Search DOE PAGES for ORCID "0000-0002-2248-8890"

Bond‐Lamberty, Benjamin  ^[2]

• Search DOE PAGES for author "Bond‐Lamberty, Benjamin"
• Search DOE PAGES for ORCID "0000-0001-9525-4633"

---

+ Show Author Affiliations

1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Smithsonian Environmental Research Center, Edgewater, MD (United States)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Joint Global Change Research Institute
3. Smithsonian Environmental Research Center, Edgewater, MD (United States)
4. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Publication Date:

Fri Jul 21 00:00:00 EDT 2023

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth & Environmental Systems Science (EESS); USDOE

OSTI Identifier:

2217132

Alternate Identifier(s):

OSTI ID: 1995550

Report Number(s):

PNNL-SA-178412
Journal ID: ISSN 2169-8953

Grant/Contract Number:  

AC05-76RL01830; DE‐AC05‐76RL01830

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Biogeosciences

Additional Journal Information:

Journal Volume: 128; Journal Issue: 8; Journal ID: ISSN 2169-8953

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; forest; methane uptake; carbon dioxide release; environmental change; extreme flooding; source partitioning