Impact of topsoil removal on soil CO2 emission and temperature sensitivity in Chinese Loess Plateau

Xin Gao; Weijia Li; Ali Salman; Rui Wang; Lanlan Du; Lunguang Yao; Yaxian Hu; Shengli Guo

doi:10.1016/j.scitotenv.2019.135102

Impact of topsoil removal on soil CO₂ emission and temperature sensitivity in Chinese Loess Plateau

Sci Total Environ. 2020 Mar 15:708:135102. doi: 10.1016/j.scitotenv.2019.135102. Epub 2019 Nov 19.

Authors

Xin Gao¹, Weijia Li¹, Ali Salman², Rui Wang¹, Lanlan Du¹, Lunguang Yao³, Yaxian Hu⁴, Shengli Guo⁵

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China.
² College of Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
³ Collaborative Innovation Center of Water Security for Water Source, Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang Normal University, Nanyang, Henan 473061, China.
⁴ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China; Collaborative Innovation Center of Water Security for Water Source, Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang Normal University, Nanyang, Henan 473061, China. Electronic address: huyaxian@nwafu.edu.cn.
⁵ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China; College of Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China; Collaborative Innovation Center of Water Security for Water Source, Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang Normal University, Nanyang, Henan 473061, China. Electronic address: guoshli@nwafu.edu.cn.

PMID: 31812399
DOI: 10.1016/j.scitotenv.2019.135102

Abstract

Soil redistribution by terrace construction, as one of the most evident anthropogenic imprints on hill-slopes, may influence soil organic carbon (SOC) dynamics through re-shaping topography and altering water and oxygen availability. However, the fundamental role and mechanisms by which terrace construction affects in situ soil CO₂ emissions and its temperature sensitivity (Q₁₀) remain poorly understood. In this study, topsoil removal-addition approach was used to simulate topsoil redistribution during terrace construction. Compared with the nearby undisturbed soil, the average annual soil CO₂ emission over two years was reduced by 24% in the topsoil removed field but enhanced by 33% in the topsoil added field. The decreased soil CO₂ emission at the topsoil removed field was largely associated with the depletion of SOC stocks and microbial biomass carbon, while the increments of SOC available for decomposition at the topsoil added field contributed to its increased soil CO₂ emissions. However, the average Q₁₀ value in the topsoil removed field was 23% greater at seasonal scale and 28% greater at diurnal scale than that in the undisturbed soil. The increased Q₁₀ in the topsoil removed field is mainly due to higher aromaticity of water-extractable organic carbon (WEOC) and the domination of Actinobacteria in keystone taxa. Overall, our results show that changes in both aromaticity of WEOC and soil microbial community composition induced by soil redistribution during terrace construction may alter the response of soil CO₂ emission to elevated temperature. Our study indicates that the impact of man-made soil redistribution should not be neglected when studying regional carbon cycling.

Keywords: Carbon quality; Microbial community composition; Q(10); Soil CO(2) emissions; Topsoil removal and addition.