EGU23-6616, updated on 25 Oct 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Mechanisms of nocturnal soil CO2 uptake influenced by a succession of biological soil crusts in drylands

Minsu Kim1, Clément Lopez-Canfin2,3, Roberto Lázaro4, Enrique P. Sánchez-Cañete2,5, and Bettina Weber6
Minsu Kim et al.
  • 1Institute of Biology, University of Graz, Graz, Austria
  • 2Department of Applied Physics, University of Granada (UGR), Granada, Spain
  • 3Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA
  • 4Department of Desertification and Geo-Ecology, Experimental Station of Arid Zones (EEZA-CSIC), Almería, Spain
  • 5Inter-University Institute for Earth System Research (IISTA-CEAMA), Granada, Spain
  • 6Multiphase Chemistry, Max Planck Institute for Chemistry, Mainz, Germany

Many dryland soils absorb atmospheric CO2 at night. Despite the relatively small annual carbon (C) uptake, ranging locally from 1 to 10 g C m-2, it may have large-scale effects, as drylands cover almost 45% of the Earth’s land surface. This process might contribute to the global missing C sink of 3.1 ± 0.9 Pg C year-1. As dryland soils have high inorganic C contents compared to organic C, mechanisms of the nocturnal CO2 uptake likely involve both biotic and abiotic processes that are tightly coupled to water availability. Biological soil crusts (hereafter, biocrusts) cover about 30% of global drylands and provide favourable physico-chemical hotspots for this C exchange mechanism. In this study, we present a mechanistic model of inorganic C binding that is enhanced by the activity of biocrust communities. The model results show good agreement with field measurements of the soil-atmosphere CO2 exchange dynamics under contrasting conditions of water availability and temperature in the Tabernas Desert (Spain). We further show that inorganic C sequestration rates at night vary, depending on the successional stages of biocrusts. Our findings have the potential to substantially improve the often-overlooked processes of dryland systems in the global C cycle. By unravelling the mechanisms occurring along the succession of biocrusts, this study highlights the roles of soil biological agents in mitigating CO2 emissions in a drier future.

How to cite: Kim, M., Lopez-Canfin, C., Lázaro, R., Sánchez-Cañete, E. P., and Weber, B.: Mechanisms of nocturnal soil CO2 uptake influenced by a succession of biological soil crusts in drylands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6616,, 2023.