In arid and semiarid regions, the presence of roads or firebreaks can affect microclimatic variables that influence the abundance of soil nesting ants. We studied ant nest density in environments with different soil types (loose and compacted soil), and vegetation cover (shrubland, grassland and bare soil) south of Caldenal, La Pampa, Argentina. We selected three areas with woody cover (shrubland), herbaceous cover (grass), and 80% of bare soil (firebreaks) within a 12 ha study area where large herbivores were excluded. We recorded soil surface temperature, humidity, pH and degree of soil compaction in each area. The density of nests was assessed by randomly placing three transects (80 m x 5 m) in each experimental unit. Soil temperature was higher in firebreaks and soil compaction was higher in the shrubland and the grassland. No differences in ant assemblage were found regarding nest density among environments. However, Acromyrmex striatus (Roger, 1863) was found mostly in firebreaks where loose soil with greater porosity allows more gas exchange and water infiltration. Our findings revealed that the construction of firebreaks favors the establishment of leaf-cutting ants, which due to their competitive advantage, could negatively affect ant and plant composition in the community.
Nesting; disturb; soil
