Bioturbation as a means to circumvent sodium limitation by termites? Suspected processes and ecological consequences

International audienceBioturbation by termites is considered a key process in the regulation of soil properties in tropical soils. The concentration of clay and the presence of 2:1 clay minerals in termite-soil are usually explained by the need of termites to build stable biogenic structures and/or to have access to water only available in the lower soil layers. However, while these hypotheses are attractive, they do not always offer a sufficient explanation for understanding termite bioturbation behavior. Here, we used ecological stoichiometry theory to propose a third hypothesis: that bioturbation can also be explained by the limitation of termites for Na +. This chemical element is missing from the vegetation consumed by termites, while it plays an important role in the regulation of termites' physiological processes. In old and highly weathered soils, such as those found in the tropics, a significant source of Na + for termites likely comes from 2:1 minerals, which are only available in the deeper soil layers. Therefore, this article aims to propose the hypothesis of the use of bioturbation by termites as a means to fulfil their need for Na +. The impacts of this ecological process on ecosystem functioning and soil fertility are discussed