Bioturbation and soil resistance to wind erosion in Southern Tunisia

Wind erosion is a major threat to the sustainability of arid and semi-arid ecosystems. In these environments, biological soil crusts positively impact soil resistance to erosion. Less is known, however, on the impact of soil bioturbation by animals. In Southern Tunisia, bioturbation is mainly carried out by termites, ants and rodents which deposit mineral and organic components on the soil surface in the form of soil sheetings for termites or as soil heaps for ants and rodents. We here question the properties of these soils and measure their resistance to wind erosion. We showed that soil sheetings are made of sand grains linked together by bridges of organic matter, clay particles and other small size minerals such as carbonates and gypsum. The stability of these aggregates is comparable to that of biological soil crusts, despite their very different organizations. Conversely, the soil excavated by ants and rodents mainly consists in individual sand grains, which are impoverished in organic carbon and prone to wind erosion. In conclusion, this study highlights the importance of termites, as key soil bioturbator, on the dynamics of soil aggregates in Southern Tunisia. It also shows that they have an opposite effect than that of ants and rodents on the resistance of soil to erosion.