Abiotic/biotic partitioning of soil CO2 flux in arid and hyper-arid soils

Resolving the role of arid and hyper-arid regions in the global carbon cycle and their influence on atmospheric CO₂ concentrations remains a significant challenge, both theoretically and practically. Theoretical challenges stem from the widespread underestimation of these seemingly lifeless regions, while practical barriers arise from the logistical and financial limitations of conducting studies in hyper-arid soils. Although a few studies have quantified surface flux and net carbon sink in these areas, most lack continuous, long-term monitoring of soil CO₂ concentrations and flux. As a result, our understanding of these regions is largely based on "snapshot" assessments, which may fail to capture their true role. Furthermore, even with knowledge of total flux, it remains a "black box" unless the contributions of biotic and abiotic mechanisms to CO₂ fluxes are disentangled. In our study, CO₂ sensors and automated flux chambers installed at subsurface and surface respectively, have been used to continuously monitor soil CO₂ concentration and flux at arid and hyper-arid sites in the Negev Desert. Based on this data, we will conduct a CO₂ source-sink assessment for each site. Biotic-abiotic partitioning analyses, utilizing modeling and isotopic tools will be used to further elucidate the sources driving CO₂ fluxes in arid and hyper-arid environments. By identifying the distinct contributions of biotic and abiotic processes to CO₂ flux, we can refine our understanding of the role arid and hyper-arid ecosystems play in the global carbon cycle and improve our predictions of how these ecosystems may respond to future climate change.