Termites Can Have Greater Influence on Soil Properties Through the Construction of Soil Sheetings Than the Production of Above-Ground Mounds

Understanding the link between termites’ impact on ecosystem functioning and their ecological needs remains a key question in ecology. This study focused on the influence of the fungus-growing termite species, Hypotermes obscuriceps, on soil properties in Southern India. This species produces soil sheetings and mounds on the ground. In contrast to other termite species, such as those belonging to the Macrotermes and Odontotermes genera, which produce mounds to live in, H. obscuriceps excavates soil above ground for constructing its chambers below ground. Using a captive colony of H. obscuriceps growing up in control conditions, we measured the soil properties (carbon content, particle size distribution, pH, electrical conductivity and concentration in soluble anions and cations) of its mound and of the sheetings it produced over the leaves of Acacia auriculiformis and on the branches of Ipomoea carnea and Lantana camara. The physical and chemical properties of H. obscuriceps mounds were very similar to those of the surrounding soil and even if rain erodes these mounds in the field, it is likely to have only a small effect on the resulting run-off water quality. In contrast, sheetings have higher clay and C contents than the surrounding soil. Their degradation by rain is likely to be associated with soil detachment and F−, Cl− and K+ export in water runoff and/or leachate. In conclusion, this study shows that this species impacts soil properties more through the construction of sheetings than mounds. This difference is explained by the ecological needs of termites. While H. obscuriceps is not dependent on soil mound properties for survival, soil sheetings’ properties are essential for providing them a protective cover.