Gradual and abrupt increase in atmospheric CO2 concentrations trigger divergent responses of microbial necromass accumulation in paddy soils
Ding, Xueli (Nanjing University of Information Science & Technology)
Yang, Dongqiao (Nanjing University of Information Science & Technology)
Hu, Zhenghua (Nanjing University of Information Science & Technology)
Shen, Lidong (Nanjing University of Information Science & Technology)
Zhang, Wei (Chinese Academy of Sciences. Institute of Applied Ecology)
Zhu, Xuefeng (Chinese Academy of Sciences. Institute of Applied Ecology)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Wu, Zhurong (Nanjing University of Information Science & Technology)
He, Hao (Nanjing University of Information Science & Technology)
He, Hongbo (Chinese Academy of Sciences. Institute of Applied Ecology)
Liang, Chao (Chinese Academy of Sciences. Institute of Applied Ecology)

Data:	2024
Resum:	Microbial necromass C (MNC) plays a critical role in promoting soil organic C (SOC) formation and stabilization, particularly in the context of climate change. Most investigations on the impact of elevated CO2 concentrations (eCO2) on MNC have been performed by exposing ecosystems to an abrupt increase in CO2. However, the atmospheric CO2 increase is a gradual process, and knowledge about the response of necromass to gradual increase in CO2 is lacking. We tested the hypothesis that microbial necromass would show different responses to abrupt and gradual CO2 increases. Furthermore, it is still unknown whether eCO2 will trigger similar responses between surface and subsurface soil layers. Here, we determined the MNC concentrations and their proportions in SOC in surface and subsurface soil layers via open-top chambers. CO2 treatments included ambient control, abrupt CO2 increase by 200 ppm above control, and gradual CO2 increase by 40 ppm each year until reaching 200 ppm over five years. Overall, compared with the ambient control, abrupt eCO2 induced a significantly stronger decrease in necromass (20. 3 %) when averaged across three soil layers, while gradual eCO2 led to insignificant variations in necromass (6. 7 %). The necromass proportion in SOC decreased with depth under both eCO2 treatments with a significant decline occurring in abrupt eCO2 treatment. The observed greater magnitude of eCO2 effects on fungal necromass relative to bacterial necromass in subsurface layers illustrates a distinct microbial community response to climate change. Taken together, abrupt and gradual eCO2 approaches differed in their impact on MNC, and its response to eCO2 may be somewhat overestimated by abrupt eCO2 approach. Furthermore, MNC in subsurface soil witnessed a more sensitivity or vulnerability to eCO2 than that of topsoil. We suggest vigilant attention will need to be paid to the feedback of necromass C in deep soil poised by future climate change.
Ajuts:	Agencia Estatal de Investigación PID2022-140808NB-I00 Agencia Estatal de Investigación TED2021-132627B-I00
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Abrupt CO2 increase ; Gradual CO2 increase ; Microbial necromass ; Soil carbon sequestration ; Soil depth ; Paddy fields
Publicat a:	Applied Soil Ecology, Vol. 202 (October 2024) , art. 105587, ISSN 1873-0272

DOI: 10.1016/j.apsoil.2024.105587

Disponible a partir de: 2026-10-30 Postprint

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