The Effects of soil-dwelling Ants on the Structure of Mediterranean Soils

The Effects of soil-dwelling Ants on the Structure of Mediterranean Soils

J. Willott (1), E. Cammeraat (2) and A. Vacca (3)

(1) International Faculty, Leeds Metropolitan University, United Kingdom, (2) Institute for
Biodiversity and Ecosystem Dynamics, The Netherlands, (3) Dipartimento di Scienze della
Terra, Università di Cagliari, Italy. J.Willott@leedsmet.ac.uk

Through their nest-building activities, soil-dwelling ants can act as environmental engineers,
having a large effect on soil physical and chemical properties, such as texture,
infiltration, porosity and nutrient concentrations. The ants bring material to the surface
and also affect the aggregation of soil particles, but their impact on soil aggregation
and soil aggregate stability is not well understood. These are important properties
as improved aggregation supports and maintains soil porosity, thereby contributing
to more stable burrows, better drainage and improved regulation of the atmosphere
within the nest. On the soil surface, aggregated soil is more resistant to slaking, reducing
the availability of material than can be transported by overland flow.
We present a study of the impact of ants on a range of soils sampled on a E-W transect
across the Mediterranean (Spain, Italy and Greece), measuring soil physical and
chemical properties but with special attention to soil aggregation and soil aggregate
stability. Ant-affected soils were compared to control sites with no visual ant activity.
There were significant differences in levels of organic carbon and inorganic nutrients
between nest soil and controls. We observed differences in texture, soil aggregation
and soil aggregate stability, including micro-aggregation and micro-aggregate stability,
induced by ant activity. We conclude that ant activity can have important consequences
for soil structure.