Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics
Abstract Experimental soil heating experiments have found a consistent increase in soil‐surface CO2 emissions (Fs), but inconsistent soil organic carbon (SOC) responses. Interpretation of heating effects is complicated by spatial heterogeneity and soil moisture, nitrogen availability, and microbial...
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American Geophysical Union (AGU)
2025-02-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004714 |
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| author | W. J. Riley J. Tao Z. A. Mekonnen R. F. Grant E. L. Brodie E. Pegoraro M. S. Torn |
| author_facet | W. J. Riley J. Tao Z. A. Mekonnen R. F. Grant E. L. Brodie E. Pegoraro M. S. Torn |
| author_sort | W. J. Riley |
| collection | DOAJ |
| description | Abstract Experimental soil heating experiments have found a consistent increase in soil‐surface CO2 emissions (Fs), but inconsistent soil organic carbon (SOC) responses. Interpretation of heating effects is complicated by spatial heterogeneity and soil moisture, nitrogen availability, and microbial and plant responses. Here we applied a mechanistic ecosystem model to interpret heating impacts on a California forest subjected to 1 m deep, 4°C heating. The model accurately simulated control‐plot CO2 fluxes, SOC stocks, fine root biomass, soil moisture, and soil temperature, and the observed increases in Fs and decreases in fine root biomass. We show that a complex suite of interactions can lead to a consistent increase in Fs (∼17%) over the 5‐year study period, with very small changes in SOC stocks (<1%). Modeled increases in leaf water stress from soil drying reduced GPP and NPP. The resulting reduction in leaf and fine root allocation increased fine root litter inputs to the soil and reduced root exudation. Soil heating led to about a 50% larger increase in root autotrophic respiration than in heterotrophic respiration, with the heating effect on both these fluxes decreasing over the simulation period. Increased heterotrophic respiration led to increased soil N availability and plant N uptake. These heating responses are mechanistically linked, of magnitudes that can affect ecosystem dynamics, and long‐term observations of them are rarely made. Therefore, we conclude that a coupled observational and mechanistic modeling framework is needed to interpret manipulation experiments, and to improve projections of climate change impacts on terrestrial ecosystem carbon dynamics. |
| format | Article |
| id | doaj-art-3439d837bdc54856a25c8d0207a4087d |
| institution | OA Journals |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-3439d837bdc54856a25c8d0207a4087d2025-08-20T02:16:06ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-02-01172n/an/a10.1029/2024MS004714Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon DynamicsW. J. Riley0J. Tao1Z. A. Mekonnen2R. F. Grant3E. L. Brodie4E. Pegoraro5M. S. Torn6Climate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAClimate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAClimate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAUniversity of Alberta Edmonton AB CanadaClimate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAClimate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAClimate and Ecosystem Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USAAbstract Experimental soil heating experiments have found a consistent increase in soil‐surface CO2 emissions (Fs), but inconsistent soil organic carbon (SOC) responses. Interpretation of heating effects is complicated by spatial heterogeneity and soil moisture, nitrogen availability, and microbial and plant responses. Here we applied a mechanistic ecosystem model to interpret heating impacts on a California forest subjected to 1 m deep, 4°C heating. The model accurately simulated control‐plot CO2 fluxes, SOC stocks, fine root biomass, soil moisture, and soil temperature, and the observed increases in Fs and decreases in fine root biomass. We show that a complex suite of interactions can lead to a consistent increase in Fs (∼17%) over the 5‐year study period, with very small changes in SOC stocks (<1%). Modeled increases in leaf water stress from soil drying reduced GPP and NPP. The resulting reduction in leaf and fine root allocation increased fine root litter inputs to the soil and reduced root exudation. Soil heating led to about a 50% larger increase in root autotrophic respiration than in heterotrophic respiration, with the heating effect on both these fluxes decreasing over the simulation period. Increased heterotrophic respiration led to increased soil N availability and plant N uptake. These heating responses are mechanistically linked, of magnitudes that can affect ecosystem dynamics, and long‐term observations of them are rarely made. Therefore, we conclude that a coupled observational and mechanistic modeling framework is needed to interpret manipulation experiments, and to improve projections of climate change impacts on terrestrial ecosystem carbon dynamics.https://doi.org/10.1029/2024MS004714soil heatingcarbon cycleecosystem carbonsoil moistureplant water stressecosystem modeling |
| spellingShingle | W. J. Riley J. Tao Z. A. Mekonnen R. F. Grant E. L. Brodie E. Pegoraro M. S. Torn Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics Journal of Advances in Modeling Earth Systems soil heating carbon cycle ecosystem carbon soil moisture plant water stress ecosystem modeling |
| title | Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics |
| title_full | Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics |
| title_fullStr | Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics |
| title_full_unstemmed | Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics |
| title_short | Experimental Soil Warming Impacts Soil Moisture and Plant Water Stress and Thereby Ecosystem Carbon Dynamics |
| title_sort | experimental soil warming impacts soil moisture and plant water stress and thereby ecosystem carbon dynamics |
| topic | soil heating carbon cycle ecosystem carbon soil moisture plant water stress ecosystem modeling |
| url | https://doi.org/10.1029/2024MS004714 |
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