Wetting‐induced soil CO2 emission pulses are driven by interactions among soil temperature, carbon, and nitrogen limitation in the Colorado Desert

Warming‐induced changes in precipitation regimes, coupled with anthropogenically enhanced nitrogen (N) deposition, are likely to increase the prevalence, duration, and magnitude of soil respiration pulses following wetting via interactions among temperature and carbon (C) and N availability. Quantif...

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Bibliographic Details
Published in:Global change biology 2023-06, Vol.29 (11), p.3205-3220
Main Authors: Andrews, Holly M., Krichels, Alexander H., Homyak, Peter M., Piper, Stephanie, Aronson, Emma L., Botthoff, Jon, Greene, Aral C., Jenerette, G. Darrel
Format: Article
Language:English
Subjects:
Ambient temperature
Anthropogenic factors
Carbon dioxide
Carbon dioxide emissions
Carbon sources
CO2 flux
Deposition
desert
Desert soils
Desertification
Deserts
Emissions
Interactive control
N deposition
Nitrates
Nitrogen
Respiration
Sandy soils
Soil
soil C and N
Soil conditions
Soil dynamics
Soil temperature
soil wetting
Soils
Temperature
Urbanization
Wetting
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Summary:Warming‐induced changes in precipitation regimes, coupled with anthropogenically enhanced nitrogen (N) deposition, are likely to increase the prevalence, duration, and magnitude of soil respiration pulses following wetting via interactions among temperature and carbon (C) and N availability. Quantifying the importance of these interactive controls on soil respiration is a key challenge as pulses can be large terrestrial sources of atmospheric carbon dioxide (CO2) over comparatively short timescales. Using an automated sensor system, we measured soil CO2 flux dynamics in the Colorado Desert—a system characterized by pronounced transitions from dry‐to‐wet soil conditions—through a multi‐year series of experimental wetting campaigns. Experimental manipulations included combinations of C and N additions across a range of ambient temperatures and across five sites varying in atmospheric N deposition. We found soil CO2 pulses following wetting were highly predictable from peak instantaneous CO2 flux measurements. CO2 pulses consistently increased with temperature, and temperature at time of wetting positively correlated to CO2 pulse magnitude. Experimentally adding N along the N deposition gradient generated contrasting pulse responses: adding N increased CO2 pulses in low N deposition sites, whereas adding N decreased CO2 pulses in high N deposition sites. At a low N deposition site, simultaneous additions of C and N during wetting led to the highest observed soil CO2 fluxes reported globally at 299.5 μmol CO2 m−2 s−1. Our results suggest that soils have the capacity to emit high amounts of CO2 within small timeframes following infrequent wetting, and pulse sizes reflect a non‐linear combination of soil resource and temperature interactions. Importantly, the largest soil CO2 emissions occurred when multiple resources were amended simultaneously in historically resource‐limited desert soils, pointing to regions experiencing simultaneous effects of desertification and urbanization as key locations in future global C balance. We compiled a comprehensive, high‐resolution dataset to characterize soil carbon dioxide (CO2) pulsed emissions following experimental wetting in the Colorado Desert. We observed some of the strongest soil CO2 pulse responses reported globally when wetting occurred in abundant C and N conditions during the hot summer, suggesting a high capacity for belowground respiration in deserts during short time periods when optimal soil microclimate and
ISSN:1354-1013
1365-2486
DOI:10.1111/gcb.16669