a somewhat different phenomenon is occupation of special habitats by species requiring unusual edaphic condition. directed dispersal has been suggested for nuts cached by birds, fruits eaten by birds, and diaspores carried to rotten logs by ants. A convincing confirmation must include a demonstration that dispersal agents take seeds to nonrandom places that are well-suited for establishment and growth. The best example come from the Australian saltbush, where closely related shrubs occupy ant mounds.
show that both ant- dispersal and nonant-dispersed congeners grow well on ant mounds, but that ant-dispersed species have demonstrably poor growth off the mound. For these and other plants, ant-assisted colonization of these well-drained and ion-rich soils appears to be obligate.