Ants mediate soil water in arid desert ecosystems: Mitigating rainfall interception induced by biological soil crusts?

• We hypothesize that ants serve as a regulator to mediate the rainfall in soil.
• We examine that ant disturbance reduces the rain interception induced by BSCs.
• Ants benefited to maintain a constant cover of shrubs in an artificial vegetation.

As vital components of desert systems, the roles of ants in arid ecological processes have been well documented, while little attention has been given to their effects on soil water. We conducted a six-year investigation in sand dune systems stabilized via revegetation, to explore the hydrological role of ants through comparing the influence of ant nests on rainfall infiltration in different-aged revegetated dunes. The presence of ant nests markedly enhanced infiltration due to weakening the rainfall interception by biological soil crusts (BSCs) in revegetated dunes. The distribution of ant nest was denser in older revegetated areas, due to better developed BSCs of later successional stages, compared to younger revegetated areas. Ants prefer later to early successional BSCs because the later lichen–moss dominated crusts were thicker and their surface was more stable than the early cyanobacteria dominated crusts. Conversely, the crustal rainfall interception was positively correlated with BSC thickness. These findings suggest that the occurrence of ant nests in older revegetated areas benefited to the planted shrubs with deeper root systems and maintain a relative constant cover of shrubs in artificial sand-binding vegetation following an increase in infiltration to deeper soil layers.