Spatial and temporal patterns of ant burrow openings as affected by soil properties and agricultural practices

To assess the interactive effect of ants with soil properties and agronomic factors, burrow abundance of the ant, Lasius neoniger (Emery), was investigated in a southern Wisconsin corn field in 1990 and 1991. The field was divided into three irrigation, two tillage, and two nitrogen treatments, and was surrounded by a border area that was periodically mowed and contained a mixture of native and exotic plants. Burrow openings were mapped weekly from July to October in 1990, and number of burrow openings per m² was measured from April to October in 1991, both years' measurements were made on replicated quadrats. Soil temperature, pH, phosphorous, potassium, organic carbon content, and plant leaf area indices were also measured on these quadrats. In general, number of ant burrows was not significantly different among different irrigation, tillage and nitrogen treatments. However, the cumulative effect of tillage may reduce the burrow openings. Soil properties such as pH, organic carbon, phosphorous, or potassium content did not seem to affect the occurrence of burrow openings. Maximum number of open burrows appeared to accur at a soil temperature (5 cm depth) of about 27°C or under vegetation cover with a leaf area index of 0.5. The burrows also were aggregated close to corn stalks. Spatially, the ant burrows were generally randomly dispersed fitting a Poisson distribution. Over time, the increase in ant burrow openings resembled a logistic function.