Soil temperature and arthropod abundance are lower near ant mounds

Abstract

Because so little of tallgrass prairie remains in North America, conservationists must monitor the general health of remaining prairie sites to ensure their survival. Disturbances are crucial to boosting overall diversity for prairies, since they create patches that allow less-dominant species to gain a foothold in the environment. In order to better understand the importance of disturbance in a savanna ecosystem, we studied the effects of a common disturbance, ant mounds, on soil conditions and on underground arthropod abundance and diversity in the savanna area of Conard Environmental Research Area (CERA), a reconstructed prairie in central Iowa. In fall 2002, we gathered soil and arthropod samples from 16 Formica montanis and Formica exsectoides ant mounds and 16 control sites, analyzed soil conditions, and identified soil arthropods. We predicted ant mounds would boost both arthropod abundance and diversity by creating soil conditions favorable to arthropods, including higher percentages of moisture and organic matter, higher temperatures, and lower levels of pH, as shown by earlier studies. However, we found that ant mounds did not significantly alter soil conditions, aside from creating lower temperatures, nor did they boost arthropod abundance or diversity. Future studies could isolate one soil factor to examine its effects on arthropods in more detail. Results from this type of study could help ecologists better understand how to successfully incorporate ant mounds into prairie ecosystems.