In desert ecosystems, harvester ants have been shown to be important granivores and seed dispersers.
Because many desert plants exist as seeds in the ground for long periods, harvester ants may greatly
influence plant population dynamics. In this study, we examine the effects of harvester ant nests on
vegetation and soil properties in a desert ecosystem dominated by the dwarf shrub Rhanterium epapposum
in Kuwait, north-eastern Arabia. Soil properties were greatly modified in the circular refuse zone around
the nests of the harvester ants, with elevated levels of nutrients (except nitrogen) and organic matter.
Plant species richness and productivity were also significantly enhanced in the refuse zone. The vast
majority of species inhabiting this zone were desert annuals, but there is no evidence to suggest that
the species involved have any distinct association with ant nests. Harvester ants therefore contribute
substantially to small-scale spatial heterogeneity in this aridland plant community. It is also suggested
that the significance of ant nests in providing favourable sites for plant growth is enhanced in drier years,
when many species in off-nest sites may die prematurely due to drought. Furthermore, because ants
occasionally abandon their nests and create new colonies, the addition of nutrient-rich patches to the
landscape over time could represent an important mechanism for maintaining fertility of desert soils,
possibly with long-term implications for plant biodiversity. Harvester ants can therefore be regarded as
a key ecosystem engineer in this relatively undisturbed desert ecosystem of Kuwait.