Response of termite mounds to changes of geomorphic forms and processes and associated edaphic variations

Abstract

Despite extensive research on edaphic variations due to termitaria development, there have been no studies dedicated toward showing how changes in geomorphological components affect the lifecycle stages of termitaria. In this study, we assessed (1) the responses of termite mounds (in terms of their life stages) to changes in geomorphic forms and processes in northeastern Iran; and (2) how extinction of termite mounds encourages a trend of land degradation in semi-arid ecosystems. Samples of soil around active, abandoned, and extinct termite mounds located on young, intermediate, and old alluvial fan surfaces were gathered. Twenty soil physicochemical properties were selected and measured to determine the comparative soil quality indices (SQI). The highest mean SQI value was observed among intermediate fans, where the greatest proportion of active mounds was located. The mean SQI for young and old fans, where the greatest proportion of abandoned mounds was located, displayed a statistically significant decrease. The SQI of areas with extinct mounds exhibited the lowest statistical value. The lower soil quality values for the old and young fans is due to seasonal and annual flooding and associated depositional processes, leading to surface instability on these landforms. The development of gully erosion processes in old fans inhibits soil development and encourages the abandoning of termite mounds. By contrast, the relative stability of the intermediate fan surfaces enables soils to develop, due to the fewer flooding, inundation, and gullying processes, prompting more stability of the termite mounds. These findings describe how environmental changes stimulated by the different geomorphic forms and processes affect the stability trend of termite mounds and lead to changes in their lifecycle stages.