Title: Localized basal area affects soil respiration temperature sensitivity in a coastal deciduous forest

Abstract

Soil respiration (R_s), the flow of CO₂ from the soil surface to the atmosphere, is one of the largest carbon fluxes in the terrestrial biosphere. The spatial variability of R_s is both large and poorly understood, limiting our ability to robustly scale it in space. One factor in R_s spatial variability is the autotrophic contribution from plant roots, but it is uncertain how the presence of plants affects the magnitude and temperature sensitivity of R_s. This study used 1 year of R_s measurements to examine the effect of localized basal area on Rs in the growing and dormant seasons, as well as during moisture-limited times, in a temperate, coastal, deciduous forest in eastern Maryland, USA. In a linear mixed-effects model, tree basal area within a 5 m radius (BA₅) exerted a significant positive effect on the temperature sensitivity of soil respiration. Soil moisture was the dominant control on R_s during the dry portions of the year, while soil moisture, temperature, and BA₅ all exerted significant effects on R_s in wetter periods. Our results suggest that autotrophic respiration is more sensitive to temperature than heterotrophic respiration at these sites, although we did not measure these source fluxes directly, and that soilmore » respiration is highly moisture sensitive, even in a record-rainfall year. The Rs flux magnitudes (0.46–15.0 µmol m^-2 s^-1) and variability (coefficient of variability 10%–23% across plots) observed in this study were comparable to values observed in similar forests. Six R_s observations would be required in order to estimate the mean across all study sites to within 50%, and 518 would be required in order to estimate it to within 5%, with 95% confidence. A better understanding of the spatial interactions between plants and microbes, as well as the strength and speed of above- and belowground coupling, is necessary to link these processes with large-scale soil-to-atmosphere C fluxes.« less

Authors:

Pennington, Stephanie C. ;

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

McDowell, Nate G.; Megonigal, J. Patrick ;

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

Stegen, James C.; Bond-Lamberty, Ben

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

Publication Date:

Fri Feb 14 00:00:00 EST 2020

Research Org.:

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

Sponsoring Org.:

USDOE

OSTI Identifier:

1599665

Alternate Identifier(s):

OSTI ID: 1602273

Report Number(s):

PNNL-SA-143158
Journal ID: ISSN 1726-4189

Grant/Contract Number:  

AC05-76RL01830

Resource Type:

Published Article

Journal Name:

Biogeosciences (Online)

Additional Journal Information:

Journal Name: Biogeosciences (Online) Journal Volume: 17 Journal Issue: 3; Journal ID: ISSN 1726-4189

Publisher:

Copernicus Publications, EGU

Country of Publication:

Germany

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; carbon cycling; temperate forest; spatial variability; soil respiration